The key to managing seasonal allergies is figuring out what you are allergic to. It could be trees, grass, ragweed pollen, or even outdoor mold in soil, vegetation and rotting wood.

Work with your doctor to narrow down the specific allergens that seem to cause your allergy symptoms. Once you've discovered your triggers, you can figure out your own allergy season.

Where you live plays a big role in when allergy season starts. In general, the farther south you go, the earlier pollination begins. But be careful, the start and end of allergy season can vary by a few weeks depending on the year:

• North: The northern United States typically sees allergy season start a little later than the rest of the country. Cooler springtime weather usually reduces the amount of flowering plants, but watch out for summer and early fall when plant blooms peak. The northwest has one clear claim to fame for allergy suffers: Its lack of ragweed. Since 3 out of 4 people with seasonal allergies are allergic to ragweed, that's one big collective sigh of relief.
  
  
  • Trees: February to June in the northwest. March to June for other northern states.
    
    
  • Grasses: May to August
    
    
  • Ragweed: No season in the northwest. August to October for other northern states.
    
    
  • Mold: Does not fluctuate by season.
    
    
• Midwest and Great Plains: Allergy season in the Midwest is typically a little shorter than in the southern United States, but be wary of grass pollen during summer. The large number of wide grassy areas (they call it the Great Plains for a reason) means grass pollen levels will stay high in this region until they starts to taper off in August.
  
  
  • Trees: February to June
  • Grasses: May to August
  • Ragweed: August to October
  • Mold: Does not fluctuate by season
    
    
• South: Southern areas of the United States may enjoy warmer climates, but they are also the first to see plants pollinating each year. Additionally, many southern locations don't see frost until late in the year, giving the south a much longer allergy season. Warmer temperatures can also mean more mold during the summer months.
  
  
  • Trees: January to June
    
    
  • Grasses: April to September in central southern states. The Southeast and Southwest have extended grass pollen seasons, from March to October.
    
    
  • Ragweed: August to November in most Southern states. Extremely southern areas (like Florida) will often see ragweed season hit as early as July. That makes July a particularly rough month in the Deep South with grass pollen, ragweed and mold all in the air at the same time.
    
    
  • Mold: June to August. Mold season may be particularly bad in coastal areas where high humidity and wet summers can make mold a problem both inside and out.