West Chicago, Illinois Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
West Chicago weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——86°57°—
- FridayJun 5Rain74%0.13″80°68°-6°
- SaturdayJun 6Heavy Showers56%0.35″80°64°0°
- SundayJun 7Overcast11%—83°66°+3°
- MondayJun 8Light Showers38%—82°65°-1°
- TuesdayJun 9Light Drizzle29%—83°68°+1°
- WednesdayJun 10Drizzle20%—85°71°+2°
PM2.5 at 8.4 µg/m³ (AQI 47) with a 0.89 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust. AQI down 30 over the last 6 hours — air quality is improving sharply.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 8.4 µg/m³ (AQI 47) with a 0.89 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.89
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:28 AM
- Moonset
- 1:48 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
West Chicago at a glance
- Today vs. normal: 13°F below the seasonal normal for this latitude
- Last frost: April 27 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
SPC Convective Outlook
Storm Prediction Center — West Chicago
SPC has placed West Chicago in the Marginal Risk category for severe thunderstorms tomorrow.
- TODAYNONENo severe risk
- TOMORROWMRGLMarginal Risk
- DAY 3MRGLMarginal Risk
Isolated severe storms possible. Limited threat for hail or damaging wind.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
West Chicago's warmest month is July (~74°F mean) and its coldest is January (~23°F). Rainfall peaks in May (4.3 inches) and bottoms out in February (1.2 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 23° | 1.3″ | 3 |
| February | 27° | 1.2″ | 3 |
| March | 38° | 2.0″ | 5 |
| April | 49° | 3.4″ | 7 |
| May | 60° | 4.3″ | 9 |
| June | 70° | 3.6″ | 7 |
| July | 74° | 3.6″ | 6 |
| August | 72° | 3.8″ | 6 |
| September | 65° | 3.0″ | 5 |
| October | 52° | 3.0″ | 6 |
| November | 39° | 2.2″ | 4 |
| December | 28° | 1.7″ | 4 |
Regional context
West Chicago's baseline climate, derived from NOAA NCEI 1991-2020 normals at the nearest reporting station, swings from a January mean of 23°F to a July mean of 74°F — a 50°F seasonal arc typical of the mid-latitude bands. Annual precipitation runs about 33.2 inches spread across roughly 66 days with measurable rain or snow each year.
Precipitation runs summer-dominant here: May averages 4.3 inches across 8.6 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while February drops to just 1.2 inches across 3.1 rainy days under drier cool-season air. The warm-season-wet rhythm lines West Chicago up with places like Winfield, IL, Wayne, IL and St. Charles, IL, where the May-September stretch delivers the bulk of the year's precipitation.
The frost-sensitive growing window opens around mid-April, when overnight lows reliably clear freezing for cool-season crops like kale, peas, spinach, and parsnips. Heat-loving transplants like tomatoes, peppers, and squash generally hold off for another 10-14 days to clear the last spring frost risk window. The window closes around mid-November, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. Those dates are 30-year averages; the actual frost-free window in a given year can vary by 10-14 days at either end. Neighborhood-scale variation in elevation and cold-air pooling means the practical last-frost date inside West Chicago can lag the regional mean by 5-10 days in low spots, and a bench position with good cold-air drainage can run a week ahead.
Similar climates: Winfield, IL, Wayne, IL, St. Charles, IL, Carol Stream, IL, Geneva, IL.
Frequently asked
- When does it freeze in West Chicago?
- West Chicago's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in West Chicago?
- May is the wettest month with about 4.3 inches of rain on average; the city receives roughly 33 inches annually.
- What is the warmest month in West Chicago?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in West Chicago?
- January is typically coldest, averaging about 23°F.
- When can I start a vegetable garden in West Chicago?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does West Chicago get?
- West Chicago averages about 66 rainy days per year.
- What hardiness zone is West Chicago?
- West Chicago's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
West Chicago, Illinois sits in a warm-summer humid continental climate zone. January means hover near 23°F while July averages 74°F — a 50°F seasonal swing.
Across the year, West Chicago receives about 33 inches of precipitation spread over roughly 66 rainy days.
The rhythm of the year is set by latitude (41.9°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.