- Climate Type
- Humid continental
Updated July 2026 · Sources cited: weather.gov, stateclimatologist.isws.illinois.edu
Good to know
Good to Know
- September to mid-October is widely considered the most pleasant time to visit with comfortable temperatures and fall foliage.
- Winter temperatures fluctuate considerably within a single week, sometimes causing rapid melt-and-refreeze cycles and ice storms.
- Spring and early summer bring frequent thunderstorms, especially in May and June, with occasional severe weather and derechos.
- Lake Michigan moderates temperatures year-round, keeping summers cooler and winters somewhat warmer than the continental interior.
- Summer heat is often humid; approximately 21 days per year reach the 90s°F, though 100°F is rare.
- Annual snowfall of ~37 inches is significant but less than cities on the downwind (eastern) shore of Lake Michigan.
- The city enjoys over 2,600 hours of sunshine annually, with summer days offering 15+ hours of daylight and winter days dropping to 9 hours.
Best Months
September to mid-October
- Temperature Range
- ~70°F declining to mid-40s°F (21°C (70°F) to 7°C (45°F))
- Reason
- Moderate temperatures, fall colors, relatively quiet period with milder weather
May to early June
- Temperature Range
- Mild to warm with significant variability
- Reason
- Spring conditions, though more unstable and windy
Worst Months
January
- Hazards
- Extremely cold nights dropping to around -19°C (-2°F); polar air outbreaks frequent
- Temperature Avg High Low
- 29.7°F to 20.7°F (-1.3°C (30°F) to -6.3°C (21°F))
- Reason
- Coldest and most windy month with frequent snowfall and polar cold spells
February
- Snowfall Avg
- 3.54 inches (90 mm)
- Precipitation
- 1.63 inches (42 mm)
- Reason
- Coldest seawater temperature, significant snowfall
December
- Precipitation
- 1.65 inches (42 mm)
- Temperature Avg
- 0°C (32°F) with lows around -3.4°C (32°F with lows around 26°F)
- Reason
- Full arrival of winter with cold temperatures and shortest days
Driest Months
December
- Precipitation
- 1.65 inches (42 mm)
February
- Precipitation
- 1.63 inches (42 mm)
Wettest Months
May
- Precipitation
- 4.8 to 5 inches (121-127 mm)
June
- Precipitation
- 4.88 inches (124 mm)
August
- Precipitation
- 4.62 inches (117 mm)
Snowfall
- Lake Effect
- Lake Michigan boosts snowfall via lake-effect snow when winds blow from north or northeast, though Chicago receives less than downwind areas due to prevailing westerly/northwesterly winter winds
- Annual Average
- 37 inches (949 mm) per year
- Snowiest Month
- January or February (~3.5 inches)
- Characteristics
- Frequent snowfall occurring several days per month; major snowstorms (10+ inches over 1-3 days) occur approximately every three years
- Snowfall Season
- November through March, with last measurable snowfall typically by April 1
Climate Type
Humid continental with cold winters, warm summers, and frequent temperature fluctuations
Annual Total
36.97 to 38 inches (939 to 965 mm) per year
Pattern Note
Moderate precipitation spread relatively evenly; wetter summers and drier winters, with summer rain often from short-lived thunderstorms rather than prolonged rainfall
Peak Temperature Season
- Season
- Summer (June-August)
- Avg Low
- 67.6°F (19.8°C (68°F))
- Avg High
- 77.5°F (25.3°C (78°F))
- Humidity
- Warm and humid
- Record High
- 105°F (41°C (106°F)) in July 1934
- Warmest Month
- August
Off Peak Temperature Season
- Season
- Winter (November-March)
- Avg Low
- 20.7°F (-6.3°C (21°F))
- Avg High
- 29.7°F (-1.3°C (30°F))
- Record Low
- -27°F (-33°C (-27°F)) in January 1985
- Coldest Month
- January
- Typical Cold Spells
- Minimum temperatures around -20°C (-4°F) occur practically every year, sometimes dropping to -30°C (-22°F)
AI-generated estimateData refreshed July 2026
Sources cited for this category
These are the sources cited in this climate & weather research for this city. Individual figures may not each trace to one of them.
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Data last updated July 2026 · Verify anything important.