Champaign, Illinois Weather
Fireflies pulse through the magnolias. Day 77 of spring. Read this microseason across nine climate regions →
Champaign weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——85°59°—
- FridayJun 5Overcast25%—85°68°0°
- SaturdayJun 6Showers60%—84°66°-1°
- SundayJun 7Light Showers33%—84°69°0°
- MondayJun 8Light Showers46%—80°69°-4°
- TuesdayJun 9Light Drizzle26%—83°66°+3°
- WednesdayJun 10Light Showers23%—87°72°+4°
Ozone at AQI 41 now. AQI down 15 over the last 6 hours — air quality is improving sharply. With UV 3.3 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 18 by mid-afternoon.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 41 now. With UV 3.3 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 18 by mid-afternoon.
- Present
- AQI 41
- UV peak
- 3.3 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 18
PM × Wind × Precip
PM2.5 at 4.9 µg/m³ (AQI 27) with a 0.94 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.94
- 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
- 4:22 AM
- Moonset
- 1:55 PM
- In sign
- ♑︎ Capricorn
Fireflies pulse through the magnolias
Champaign at a glance
- Today vs. normal: 13°F below the seasonal normal for this latitude
- Last frost: April 17 (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 — Champaign
SPC has placed Champaign in the General Thunderstorms category for severe thunderstorms tomorrow.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
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
July stands as Champaign's warmest month with mean temperatures around 75°F, while January claims the coldest spot at roughly 26°F. May brings peak rainfall at 4.8 inches, contrasting with February's drier 2.2 inches.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 26° | 2.3″ | 5 |
| February | 30° | 2.2″ | 5 |
| March | 41° | 2.8″ | 6 |
| April | 52° | 3.9″ | 8 |
| May | 63° | 4.8″ | 9 |
| June | 72° | 4.6″ | 7 |
| July | 75° | 4.5″ | 7 |
| August | 74° | 3.5″ | 6 |
| September | 67° | 3.4″ | 5 |
| October | 55° | 3.4″ | 6 |
| November | 41° | 3.2″ | 6 |
| December | 31° | 2.4″ | 5 |
Regional context
Located within a humid subtropical climate region, Champaign shares temperature ranges, seasonal rhythms, and growing conditions with other nearby cities in this climate zone.
Similar climates: Peoria, IL, Springfield, IL, Bloomington, IL, Alton, IL, Decatur, IL.
Naturalist notes
Red-winged blackbirds return to cattail marshes around Champaign in mid-March, their territorial calls marking spring's arrival.
Wild bergamot begins blooming in late May, attracting native bees to prairie remnants throughout the area.
Frequently asked
- When does it freeze in Champaign?
- Spring's last frost usually occurs around mid-April in Champaign, while the first fall frost typically arrives around mid-November.
- What is the rainy season in Champaign?
- May records the highest rainfall with about 4.8 inches on average, contributing to the city's annual total of roughly 41 inches.
- What is the warmest month in Champaign?
- July typically registers as the warmest month, with average temperatures around 75°F.
- What is the coldest month in Champaign?
- January typically records as the coldest month, with average temperatures around 26°F.
- When can I start a vegetable garden in Champaign?
- Cool-season crops like peas and lettuce can be planted around the last spring frost in mid-April, while warm-season crops such as tomatoes and peppers should wait 1–2 weeks after.
- How many rainy days does Champaign get?
- Champaign experiences about 74 rainy days per year on average.
- What hardiness zone is Champaign?
- Champaign's USDA hardiness zone depends on its lowest average winter temperatures; the USDA's online lookup tool can provide the current zone designation using the city ZIP code.
Climate
Champaign, Illinois experiences a humid subtropical climate. Winter temperatures in January hover near 26°F, while July brings averages around 75°F — creating a 50°F seasonal swing.
Annual precipitation totals about 41 inches, distributed across roughly 74 rainy days throughout the year.
Weather patterns here respond to the city's latitude of 40.1°N, its distance from major water bodies, and local elevation. These factors determine growing seasons, frost timing, and daily weather variations.