Annual Weather Forecasting in Illinois based on Month

Illinois experiences distinct seasonal weather patterns throughout the year. January and February are typically the coldest and driest months, with average high temperatures below freezing and snowfall common. Spring (March-May) brings a transition with rising temperatures and increasing precipitation, with May and June being the wettest months. Summers (June-August) are warm and humid, with July often being the hottest month. Fall (September-November) features a gradual cooling trend with some periods of pleasant, sunny weather and decreasing precipitation. 

Winter (December-February):

• December:

  Temperatures start to drop, with average highs around 37°F (2.7°C) and lows around 22°F (-5.5°C). Snowfall is likely, especially later in the month. 

   

• January:

  The coldest month, with average high temperatures around 26°F (-3.3°C) and lows around 11°F (-12°C). Snowfall is common, and wind chill can make it feel much colder. 

   

• February:

  Temperatures begin to rise slightly, with average highs around 31°F (-0.5°C) and lows around 15°F (-9.4°C). Snowfall is still likely, but there's a chance of some milder days. 

Spring (March-May):

• March:

  Temperatures start to climb, with average highs around 41°F (5°C) and lows around 26°F (-3°C). Snowfall may still occur early in the month, but the weather will become increasingly milder and wetter. 

   

• April:

  Temperatures continue to rise, with average highs around 52°F (11.1°C) and lows around 37°F (2.7°C). Precipitation increases, with more rain than snow. 

   

• May:

  Temperatures are mild, with average highs around 64°F (17.7°C) and lows around 47°F (8.3°C). This is one of the wettest months, with frequent rain showers. 

Summer (June-August):

• June:

  Temperatures continue to rise, with average highs around 76°F (24.4°C) and lows around 57°F (13.9°C). It's still relatively wet, with June being another one of the wettest months. 

   

• July:

  The hottest month, with average highs around 84°F (28.9°C) and lows around 63°F (17.2°C). Humidity is often high, and there's a chance of thunderstorms. 

   

• August:

  Temperatures remain warm, with average highs around 81°F (27.3°C) and lows around 61°F (16.3°C). It's still relatively humid, but there's a gradual decrease in rainfall compared to June and July. 

Fall (September-November):

• September:

  Temperatures start to cool down, with average highs around 76°F (24°C) and lows around 54°F (12°C). Rainfall decreases, and the weather can be pleasant with sunny days.

• October:

  Temperatures continue to drop, with average highs around 63°F (17.2°C) and lows around 42°F (5.6°C). Snowfall is possible later in the month, especially in northern Illinois.

• November:

  Temperatures are cold, with average highs around 45°F (7.2°C) and lows around 29°F (-1.7°C). Snowfall is common, and the winter weather begins to set in.