Caledonia, Illinois Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
Caledonia weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——82°49°—
- ThursdayJun 4Overcast——86°57°+4°
- FridayJun 5Heavy Showers82%0.74″74°66°-12°
- SaturdayJun 6Heavy Showers61%1.1″80°63°+6°
- SundayJun 7Overcast13%—78°58°-2°
- MondayJun 8Heavy Drizzle29%0.16″78°61°0°
- TuesdayJun 9Light Drizzle23%0.02″79°68°+1°
Ozone at AQI 60. AQI up 37 in the last 6 hours — air quality is degrading. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
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 60. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
- Present
- AQI 60
- UV peak
- 0.2 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 7
PM × Wind × Precip
PM2.5 at 8.9 µg/m³, PM10 at 10.9 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.82
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
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
- 4:33 AM
- Moonset
- 1:50 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Caledonia at a glance
- Today vs. normal: 6°F above the seasonal normal for this latitude
- Last frost: April 30 (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 — Caledonia
SPC has placed Caledonia in the Marginal Risk category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- 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 | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Caledonia's warmest month is July (~74°F mean) and its coldest is January (~22°F). Rainfall peaks in June (5.2 inches) and bottoms out in January (1.6 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 22° | 1.6″ | 4 |
| February | 26° | 1.6″ | 4 |
| March | 37° | 2.4″ | 5 |
| April | 49° | 3.8″ | 7 |
| May | 60° | 4.2″ | 8 |
| June | 70° | 5.2″ | 8 |
| July | 74° | 3.8″ | 6 |
| August | 72° | 4.2″ | 6 |
| September | 64° | 3.6″ | 5 |
| October | 52° | 2.6″ | 5 |
| November | 39° | 2.3″ | 5 |
| December | 27° | 1.9″ | 5 |
Frequently asked
- When does it freeze in Caledonia?
- Caledonia's last spring frost typically falls around mid-May, and the first fall frost arrives around mid-October.
- What is the rainy season in Caledonia?
- June is the wettest month with about 5.2 inches of rain on average; the city receives roughly 37 inches annually.
- What is the warmest month in Caledonia?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in Caledonia?
- January is typically coldest, averaging about 22°F.
- When can I start a vegetable garden in Caledonia?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-May); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Caledonia get?
- Caledonia averages about 69 rainy days per year.
- What hardiness zone is Caledonia?
- Caledonia'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
Caledonia, Illinois sits in a warm-summer humid continental climate zone. January means hover near 22°F while July averages 74°F — a 52°F seasonal swing.
Across the year, Caledonia receives about 37 inches of precipitation spread over roughly 69 rainy days.
The rhythm of the year is set by latitude (42.4°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.