Plainfield, Illinois Weather
Fireflies rise from the lawn. Day 76 of spring. Read this microseason across nine climate regions →
Plainfield weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——83°50°—
- ThursdayJun 4Overcast——87°57°+4°
- FridayJun 5Drizzle64%0.03″79°67°-8°
- SaturdayJun 6Light Showers64%—82°65°+3°
- SundayJun 7Overcast17%—81°61°-1°
- MondayJun 8Drizzle21%—82°67°+1°
- TuesdayJun 9Light Drizzle21%0.01″78°68°-4°
Ozone at AQI 80 — peak already passed at 1 PM under clear skies. AQI up 9 over the last 6 hours (gradual rise). Levels should ease through evening.
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 80 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 80
- UV peak
- 5.7 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 80
PM × Wind × Precip
PM2.5 at 5.0 µg/m³ (AQI 28) with a 0.79 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.79
- 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).
The higher the clouds, the finer the weather.
- Moonrise
- 3:51 AM
- Moonset
- 12:45 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Plainfield at a glance
- Today vs. normal: 9°F above the seasonal normal for this latitude
- Last frost: April 26 (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 3, 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 — Plainfield
SPC has placed Plainfield in the Marginal Risk category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe 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
Plainfield's warmest month is July (~74°F mean) and its coldest is January (~24°F). Rainfall peaks in July (4.5 inches) and bottoms out in February (1.8 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 24° | 2.0″ | 5 |
| February | 28° | 1.8″ | 5 |
| March | 38° | 2.3″ | 5 |
| April | 49° | 3.9″ | 7 |
| May | 60° | 4.5″ | 8 |
| June | 70° | 4.3″ | 7 |
| July | 74° | 4.5″ | 6 |
| August | 72° | 4.0″ | 6 |
| September | 66° | 3.2″ | 5 |
| October | 53° | 3.1″ | 6 |
| November | 40° | 2.5″ | 5 |
| December | 29° | 1.9″ | 5 |
Regional context
Plainfield sits within a warm-summer humid continental climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Chicago, IL, Rockford, IL, Round Lake Beach, IL, Aurora, IL, Naperville, IL.
Frequently asked
- When does it freeze in Plainfield?
- Plainfield's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Plainfield?
- July is the wettest month with about 4.5 inches of rain on average; the city receives roughly 38 inches annually.
- What is the warmest month in Plainfield?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in Plainfield?
- January is typically coldest, averaging about 24°F.
- When can I start a vegetable garden in Plainfield?
- 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 Plainfield get?
- Plainfield averages about 70 rainy days per year.
- What hardiness zone is Plainfield?
- Plainfield'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
Plainfield, Illinois sits in a warm-summer humid continental climate zone. January means hover near 24°F while July averages 74°F — a 50°F seasonal swing.
Across the year, Plainfield receives about 38 inches of precipitation spread over roughly 70 rainy days.
The rhythm of the year is set by latitude (41.6°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.