By many accounts, we're in for a rough go of it this fall allergy season, thanks to the warmer-than-usual year we've been having.

"[Hot temperatures] are telling plants to produce more pollen, in some cases three to four times more pollen than usual," Cliff Bassett, M.D., a New York allergist and fellow with the American College of Allergy, Asthma and Immunology, told Weather.com. That could mean a ragweed season that’s as much as a month longer than usual, he said, running until November in some places.

The news comes on the tail of an earlier-than-normal spring allergy season, which oddly coincided with a delayed flu season, both likely due to the unseasonably warm 2011/2012 winter.

While the spring allergy season confronted the sneezy masses with sky-high pollen counts as plants and trees and flowers bloomed early, fall offers its own crop of troublesome allergens to contend with.

The only way to truly tell what it is that's causing your symptoms, however, is through testing, says Dean Mitchell, M.D., an allergist in private practice and a clinical professor at Touro College of Osteopathic Medicine in New York City. "It's tricky," he says about diagnosing allergies, since in many patients, the symptoms could be confused for the common cold. It's also important to make sure people aren't simply allergic to a pet at home, he tells The Huffington Post.

Below, you'll find the most common causes of fall allergies, plus how to avoid them. And tell us in the comments if you've noticed your allergies acting up earlier than usual.

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  • Trigger #1: Ragweed

    Spring allergies are typically brought on by the abundance of tree and grass pollen in the air, but this plant just happens to pollinate toward the end of summer, says Mitchell. Up to 20 percent of Americans are <a href="http://www.aafa.org/display.cfm?id=9&sub=19&cont=267" target="_hplink">allergic to ragweed</a>, which grows across the country but is most often found in eastern and Midwestern states, according to the Asthma and Allergy Foundation of America. A ragweed allergy causes what's commonly referred to as <a href="http://www.mayoclinic.com/health/hay-fever/DS00174/DSECTION=causes" target="_hplink">hay fever</a> (which, incidentally, has little to do with hay or a fever). Symptoms include the classic <a href="http://www.mayoclinic.com/health/hay-fever/DS00174/DSECTION=symptoms" target="_hplink">signs of allergies</a>: A runny nose or congestion, watery or itchy eyes, sneezing, coughing, itchiness, sinus pressure and dark circles under the eyes, according to the Mayo Clinic.

  • How To Avoid Ragweed

    Pollen can travel far -- as much as 400 miles away from the plant -- so it's tricky to avoid if it's causing your symptoms, says James Sublett, M.D., chair of the American College of Allergy, Asthma and Immunology's (ACAAI) Indoor Environment Committee. "Even with pollution, we've seen it grow in inner cities and the countryside -- you can't really get away from it," he says. But there are some measures that can at least alleviate symptoms a little, he says. If you have yardwork to do, try wearing a protective mask, suggests Sublett, and on very windy days when pollen counts may be high, stay indoors with windows and doors closed when you can. A high-efficiency furnace filter in the heating or air conditioning system in your home can also help capture some pollen particles, he says.

  • Trigger #2: Mold

    People tend to think of <em>indoor</em> mold when it comes to mold allergies, says Sublett, but we may actually have more exposure to outdoor mold. Outdoor mold can cause symptoms year-round, but in the autumn, <a href="http://www.webmd.com/allergies/guide/fall-allergy-relief" target="_hplink">mold spores can thrive in all those wet, fallen leaves</a>, reports WebMD. Symptoms -- such as <a href="http://www.mayoclinic.com/health/mold-allergy/DS00773/DSECTION=symptoms" target="_hplink">sneezing, a stuffy nose, and itchy eyes</a>, nose or throat -- are similar to those experienced with ragweed allergies, according to the Mayo Clinic, which is why experts say it's so important to be tested by an allergist so you can pinpoint what exactly is bothering you.

  • How To Avoid Mold

    You'll most likely encounter outdoor mold if you're raking leaves, mowing the lawn, working with mulch or trimming the shrubs this fall, says Sublett, so wear a mask when you're stuck with those chores. And not just any mask. That blue one you have leftover from painting the bathroom probably won't cut it. Look for something a little more advanced called a NIOSH N95 particulate respirator, he says. (You can find them on <a href="http://www.amazon.com/NIOSH-N95-Respirator-Dust-Mask/dp/B0017DRLJ2" target="_hplink">Amazon</a>.)

  • Trigger #3: Dust Mites

    About <a href="http://www.aafa.org/display.cfm?id=9&sub=18&cont=228" target="_hplink">20 million Americans have a dust mite allergy</a>, according to the Asthma and Allergy Foundation of America. The mites thrive in warm, humid weather, but the allergens in their waste products can get stirred up into the air when you first <a href="http://www.webmd.com/allergies/guide/fall-allergy-relief" target="_hplink">turn on the heat in the fall</a>, according to WebMD. Symptoms are also similar to a ragweed or mold allergy: <a href="http://www.mayoclinic.com/health/dust-mites/DS00842/DSECTION=symptoms" target="_hplink">Sneezing, a runny nose, itchy or watery eyes</a>, congestion and coughing are all common, according to the Mayo Clinic.

  • How To Avoid Dust Mites

    Vacuuming and other cleaning chores can stir up dust, so Sublett recommends donning that mask again. Many people with allergies have luck with a HEPA air filters in their homes. He also recommends looking for mite-proof encasing for bedding and pillows, and washing bedding regularly with hot water to kill mites (as well as mold). Whenever possible, smooth surfaces are best -- swap carpets for wood floors if you can, and opt for wipeable materials on furniture.

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