2021 Tick Forecast

As “tick expert” Dr. Thomas Mather says, “Tick season is pretty much every season.”

Still, climatic conditions can make some years worse for ticks than others. Ticks thrive in humidity, so a wet year can boost populations and increase the number of places they can live in. And warm winters and lingering summer heat add weeks of activity for the animals that ticks use as hosts, making them more likely to spread into the areas where humans live.

For 2021, forecasters predict that the warm-weather months in the US will be a bad time for anyone who wants to avoid ticks, with tick populations likely to be larger than usual, and weather conditions likely to put ticks in range of people for much longer than average. And while some regions, most notably the Southeast, may not see more tick activity than usual, most states will experience the warmer, wetter conditions that drive tick populations—and the prospect of tick borne diseases—skyward.

The Northeast has been getting warmer over the past few decades, and this year is no exception, with the National Weather Service, predicting a 70 to 80 percent chance of summer temperatures ranging above average this spring and summer. At the same time, however, some forecasters, including the National Pest Management Association, are forecasting a summer that’s cooler than recent years and wetter than average. Since humidity is a big driver of tick populations and activity during the warmer months, this means that the northeast will see more tick activity in 2021 across the region, with tick season lasting from around April to mid-to-late October.

Tick-borne diseases affecting the Northeast include Lyme disease, Rocky Mountain spotted fever, anaplasmosis, babesiosis, and tularemia.

Ticks love hot weather—warm days and nights mean that their hosts stay active, and mean bigger populations of tick species in general. And the Southeast, including Florida, Georgia, and the Carolinas, get plenty of hot weather every year. And though you can expect tick activity to decline when nightly temperatures go below 45 degrees for several days at a time (even if the ticks themselves don’t die), in some parts of the southeast, like central and south Florida, this never happens, meaning that it’s tick season year-round. As winters become milder farther north, tick season in the wider southeast has also begun to extend, so that there’s relatively few months in the year when an extended period outdoors doesn’t warrant being vigilant about ticks. In fact, tick season 2021 will go all the way to late fall in the southeast US.

The good news, however, is that the southeast isn’t facing the certainty of a warmer-than-usual year, which would make ticks even more of a concern. This winter the southeast saw cooler than usual weather, and the CDC sees only a 50 percent chance that temperatures will be warmer than usual over the summer, which means that ticks are unlikely to be more active, and that tick season will end with the fall across most of the region.

Tick-borne diseases affecting the Southeast include Lyme disease, Rocky Mountain spotted fever, anaplasmosis, babesiosis, and tularemia

The Midwest has some of the most abundant and diverse populations of ticks across the whole country. And because its natural areas so strongly resemble those of the northeast in terms of climate, the midwest is also a center for Lyme disease: apart from New England, the states around the great lakes see more cases of Lyme disease than any other region. Still, when it comes to ticks, there’s some good news for most of the Midwest. This winter and spring will likely see temperatures stay around normal, so tick season won’t begin any earlier than its usual late April start. Summer heat, however, is expected to linger, pushing September and October temperatures above average and extending tick season into the fall. In the lower midwest, however, a wetter than usual spring, coupled with a lot of severe flooding, is going to extend the habitats of many tick species, and make those areas habitable for longer than usual. So there could be a significant increase in tick activity in places like Missouri and the Ohio River valley.

Tick-borne diseases affecting the Northeast include Lyme disease, Rocky Mountain spotted fever, anaplasmosis, babesiosis, and tularemia.

The constantly warm Southwest would seem like a perfect breeding ground for ticks, but the truth is that ticks need humidity to thrive, and the Southwest gets so much more sun than rain that it’s a relatively tick-free area. As it happens, however, an El Niño weather pattern in the Pacific Ocean is going to make wide stretches of the southwest—including Texas, Oklahoma, and Arizona—more humid than usual for the first four months of 2021.

This means ticks will be more active than usual, and more likely to cross paths with potential human hosts. This humidity, combined with the usual warm summer temperatures, will extend tick season farther into the fall even for areas that can normally expect some relief thanks to cooler temperatures. The Pacific coast, however, is a different story: while California and Nevada experienced the same warmer and wetter winter, the forecasts show a drier summer than usual, making ticks less widespread than they’d be in an average year.

Tick-borne diseases affecting the Southwest include Lyme disease, Rocky Mountain spotted fever, babesiosis, and tularemia.

The Northwest is famous for its damp weather, though the big months for ticks tend to see drier conditions, with only a couple of inches per month standard for the spring and summer across Oregon, Washington, northern California, and Idaho. Still, the conditions aren’t dry enough to make ticks less of a problem.

As it happens, this year summer in the Northwest is expected to be warmer than usual, and the trend will continue into the fall, according to the National Weather Service. Forecasts also suggest that some parts of the region may end up drier than usual, though other parts may see more rainfall, but either way the Northeast is likely to provide the same beneficial habitat that it always does for ticks, making vigilance essential for those venturing into the outdoors in the region. The warmer summer conditions will extend tick season into late October and early November, so residents need to be on guard against ticks much longer than usual.

Tick-borne diseases affecting the Northeast include Lyme disease, Rocky Mountain spotted fever, anaplasmosis, babesiosis, and tularemia.

To reach our conclusions on the tick population forecast, we studied historical weather datasets and analyzed a number of predictive weather models, including the trends of major weather events (including hurricanes, floods, and weather patterns such as El Niño) from:

• The National Weather Service
• The National Oceanic and Atmospheric Administration (NOAA)
• The European Centre for Medium-Range Weather Forecasts (ECMWF)
• The World Meteorological Organization (WMO)
• The National Pest Management Association (NPMA)

In addition, we factored in available tick data from the Centers for Disease Control and Prevention (CDC).

The weather models showed how likely it was that precipitation totals and temperatures would be higher or lower than average during each month of the year. We took these weather models and compared them to where ticks are present and are becoming more populous in each region of the country. Once we distilled, cross-referenced, and computed the data, we came to reasonable conclusions based on trends seen in tick populations over time.

Weather plays such a big role in tick populations because the environment plays a big role in ticks’ reproductive cycles, which begins when a female tick lays its eggs in a wet, warm environment. After the eggs hatch, the new ticks need to feed off a host for every step of its development. This means a humid environment is essential for ticks to reproduce, and a wet winter and early spring can enable more eggs to hatch than usual. After that, weather is a factor largely because of the effect that weather has on tick hosts like mice, deer, and other animals: if winter and spring conditions lead to a big increase in mice populations, for example, then tick larvae and nymphs will have an easier time finding hosts and will be more likely to make it to the next stage of their development, and so on. And fair weather—a dryer or warmer than usual summer or fall, for example—can make hosts more active, increasing the likelihood that ticks will be carried into areas closer to humans (and making humans more likely to venture into the areas where ticks are numerous). Here’s a quick look at the stages of tick development:

• Larvae — Even fresh out of the egg, tick larvae look like tiny versions of adult ticks, and they tend to latch on to smaller animals to get the bloodmeal that will propel them into the next stage of their life cycle. This phase tends to present the least danger to humans in terms of disease: while some diseases can be passed on from the female ticks to the eggs, most of the diseases ticks carry come from the hosts whose blood they feed on, making it unlikely that a larvae will transmit an infection.
• Nymphs — The next phase of the tick life cycle presents a significant danger to humans: Rocky Mountain spotted fever, for example, is often transmitted by tick nymphs. Nymphs are also tiny, which makes them extremely difficult to spot, and they are most active in the spring and summer months, when people are most likely to be out and less protected by clothing.
• Adult — When a tick reaches the adult stage, they require a bloodmeal in order to produce eggs. And while the good news is that male adults rarely latch on to a host, the bad news is that adult female ticks do need hosts, and tend to latch on to larger animals—including humans—than tick larvae or nymphs do. Adults are most active from late fall to spring.

This disease is spread by deer ticks (blacklegged ticks) in the eastern U.S., and in the western U.S., it is spread by the western blacklegged tick and the Rocky Mountain wood tick. Lyme disease is caused by the Borrelia bacteria (which is typically picked up from animal hosts) and it typically shows itself as a “bull’s-eye” rash with a ring of red skin around a red and swollen tick bite. Additional symptoms are fever, fatigue, and headaches, and if left untreated, the disease can spread to the nervous system.

The regions where you are most likely to be infected by ticks carrying Lyme disease are:

• The Northeast
• North-Central states including Minnesota and Wisconsin
• Northern California

There are more than 30,000 cases of Lyme disease reported to the CDC each year, but the agency expects the real number of cases to be 10 times that amount.

This is a severe bacterial disease that can affect your organs if left untreated for an extended period of time. It’s spread by the Rocky Mountain wood tick, the American dog tick, the brown dog tick, and others.

The primary symptoms of Rocky Mountain spotted fever are a fever, headaches, nausea, and a rash. The disease got its name from having been first identified in the Rocky Mountain region, and from the deep red spotted rash it causes near the bite. It can take up to two weeks for symptoms to appear, but rashes usually show up within four or five days.

The Mayo Clinic says that Rock Mountain spotted fever can cause:

• Kidney failure
• Brain inflammation
• Lung inflammation
• Amputation of limbs

Rocky Mountain spotted fever can also kill you if left untreated. There is an 80 percent death rate among those who don’t treat the disease.

There are more than 3,000 cases of Rocky Mountain spotted fever reported every year. Despite its name, more than 60 percent of cases are reported in five states beyond the Rockies: North Carolina, Tennessee, Oklahoma, Arkansas, and Missouri, according to the CDC. It’s also prevalent in states in the Southeast.

Babesiosis is a disease transmitted by the deer tick (also known as the blacklegged tick). It is far more rare than Lyme disease or Rocky Mountain spotted fever, but the symptoms are just as severe. Some of the moderate symptoms of Babesiosis include:

• Fever
• Chills
• Nausea
• Body aches
• Fatigue

This disease gets into your red blood cells, and if it’s left untreated for long enough it can start to destroy red blood cells and cause a rare form of anemia. This can result in organ failure, blood clots, or death, according to the New York Department of Health.

Babesiosis is most commonly found in the Northeast in states such as New York and Connecticut. About 1,000 to 2,000 cases are reported every year.

This disease is spread by the American dog tick and the Rocky Mountain wood tick, among others. It can infect humans and animals, and it can be spread from infected animals to humans. General symptoms include fever, abdominal pain, fatigue, and nausea, though other symptoms differ depending on which version of tularemia you have. These symptoms range from chest pain to ulcers to conjunctivitis. You can view a full list of symptoms for various forms of tularemia here.

Cases of tularemia have been reported in every continental state and Alaska.

Ehrlichiosis is spread by the lone star tick in the Southeast and Midwest. This disease can cause symptoms like general soreness around the body, fever, abdominal pain, diarrhea, and rash. The symptoms typically take around 5 to 14 days to develop.

This disease is spread by deer ticks (also known as the blacklegged tick). Anaplasmosis is most often found in the same general region as Lyme disease, which includes the Northeast and Midwest. The primary symptoms of Anaplasmosis are:

• Fever
• Severe headaches
• Muscle aches
• Mild anemia

Cases of anaplasmosis have increased drastically from a few hundred cases in 2000 to more than 5,000 in 2017. This is due in part to a better understanding of the disease and also an expanding population of ticks over the same period of time.

Ticks spread disease by latching on to their hosts: as they remain attached, pathogens that live in the tick’s digestive system make their way into the host’s body and bloodstream. So how can you prevent ticks from latching onto you and spreading disease?

Ticks don’t fly, they don’t jump, and they don’t usually crawl on to their hosts from the ground. Instead, ticks reach their hosts by “questing”—having discovered high-traffic areas via scent or heat detection (or, occasionally, by detecting shadows), they climb up on nearby leaves and grass, hold on to their perch using their hind legs, and catch a ride on a host by grabbing with their two front legs. Knowing this, it’s easy to see how the following precautions would work:

Repellents like DEET and picaridin help prevent ticks from getting on you in the first place. But if they do get on you, they can help to kill the tick. You can spray DEET on your clothes and skin, but Picaridin can only be sprayed on your clothes, and not your skin. Permethrin is also effective against ticks when applied to clothing.

Wearing long sleeves, long socks, long pants, and high-ankle shoes/boots can help prevent ticks from latching onto your body. You usually won’t notice a tick crawling on you, especially in its tiny nymph stage, so it’s important to try and stop the ticks from getting on your body in the first place. Tucking your pants into your shoes or socks can stop the tick from finding anywhere on your body to latch onto. Wearing long sleeves and pants can also prevent them from latching onto you should they crawl to these areas on the outside of your clothes. Hopefully by the time they make it to an open area, they will have ran across enough repellent to kill them or have them fall off.

This sounds easy enough, but do you know where the most tick-infested areas are? They could be anywhere, but ticks most often choose dense, moist locations with plenty of shade such as shrubbery and forested areas. Make sure you’re wearing protective clothing and/or using repellant when entering these areas.

Check your scalp and skin after you’ve had a potential exposure. If by chance you find a tick on you (they may look like dirt, so grab a magnifying glass or your phone’s camera), you should remove the tick. While it may have already been on you long enough to transfer a disease, get rid of it immediately. Remove the tick with tweezers or your fingers. Properly kill the tick by dousing it with rubbing alcohol. Clean the area on your arm with hot water and soap. Keep note of the day you removed the tick and watch out for any symptoms of tick-borne diseases.

Wilderness areas are the most likely to expose you to ticks, but they’re also a threat in residential areas. That, again, is because ticks are spread by their hosts, and the most common hosts for ticks, including mice, deer, and other mammals, aren’t confined to wilderness areas. Mice are everywhere, and as development takes our homes farther and farther out into what used to be countryside, deer are more common in suburban spaces as well. So you should take all the precautions you might take in wilderness areas after you’ve been outdoors even in your own neighborhood. There are also some precautions you can take to keep ticks from being a threat near your home.

Insecticides can help kill any ticks in and around your yard. You can buy permethrin-based insecticides at the store, or you can hire a pest control expert to handle the issue. If you’re doing it yourself, make sure to strictly follow the directions on the container. Apply the insecticide when it is dry and there is no rain in the forecast for the next few days

Mice are a crucial host for ticks, and it’s about as easy to keep mice out of your yard as it is to keep out wind and rain. But there is an innovative solution available: the pest-control manufacturer Thermacell offers tick control tubes—tubes filled with permethrin-soaked cotton balls that mice take back to their nests. These cotton balls then kill the ticks that have latched onto the mice, eliminating them as a potential host.

You can help make your home a tick-free area by keeping your yard free of clutter. Get rid of any dead tree branches or shrubbery, and keep plant life trimmed and flowing. Trim the grass and keep any returning wildlife out of your yard.

The soil under a grassy lawn holds in moisture, making it a perfect place for ticks to lay their eggs and for those eggs to hatch. Keeping your grass short reduces the amount of moisture in the lawn, however, making eggs less viable and making ticks less likely to lay their eggs in your yard.

Two of the most prevalent species of American ticks have dog in their name—the American dog tick and the brown dog tick. Dogs are particularly susceptible to becoming tick hosts and carriers, making them perfect for transferring ticks from outside to inside your home.

Unfortunately, too, there are a number of tick-borne diseases that can affect dogs as well. Dogs are at risk of infection from many of the threats that humans face from ticks, including:

• Lyme disease — spread by the deer tick and western blacklegged tick. Symptoms in dogs include joint problems, lack of appetite, lassitude, and fever.
• Ehrlichiosis — one of the most dangerous tick-borne diseases for dogs. Symptoms in dogs include swelling, lassitude, lack of appetite, nose bleeds and a runny nose.
• Rocky Mountain spotted fever — spread by the American dog tick, the wood tick, and the lone star tick. Symptoms in dogs include fever, joint issues, nerve issues, and lesions on the skin.
• Babesiosis — spread by the American dog tick and the brown dog tick. Symptoms in dogs can include weakness and vomiting.
• Bartonellosis — spread by the brown dog tick. Symptoms in dogs include lameness and fever.

Keeping ticks off your pets can be easier than keeping them off yourself, however. You can try these strategies:

• Check your pets – Especially if they’ve been outside for a while, check your pet’s skin to see if you can spot any ticks and promptly remove them if you do.
• Use anti-tick medications – Consult with your vet, but there are a few medications available that will prevent ticks from latching on to your dog and prevent ticks from reproducing. These medications can come in pill and topical forms.
• Keep ticks out of your yard – As noted above, there are a number of strategies that can help you reduce tick populations in your yard if that’s where your dog spends most of its time. In particular, keeping your grass mowed and keeping tall weeds down can help prevent ticks from latching on and infecting your best friend with a serious disease.