Forest Park, Illinois Weather
Fireflies rise from the lawn. Day 78 of spring. Read this microseason across nine climate regions →
Forest Park weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 5Drizzle52%0.03″83°70°—
- SaturdayJun 6Showers34%1.5″86°68°+3°
- SundayJun 7Drizzle21%—83°66°-3°
- MondayJun 8Drizzle58%—73°68°-10°
- TuesdayJun 9Light Drizzle45%0.01″84°69°+11°
- WednesdayJun 10Drizzle30%—85°70°+1°
- ThursdayJun 11Light Drizzle——92°74°+7°
AQI 79 (Moderate), driven by PM2.5. AQI down 20 over the last 6 hours — air quality is improving sharply. PM2.5 at 10.0 µg/m³, PM10 at 11.3 µg/m³ — typical background levels with no transport signature.
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 46. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
- Present
- AQI 46
- UV peak
- 3.3 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 10
PM × Wind × Precip
PM2.5 at 10.0 µg/m³, PM10 at 11.3 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.88
- 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).
The higher the clouds, the finer the weather.
- Moonrise
- 4:56 AM
- Moonset
- 2:54 PM
- In sign
- ♒︎ Aquarius
Fireflies rise from the lawn
Forest Park at a glance
- Today vs. normal: 74°F — typical for the season
- 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 5, 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 — Forest Park
SPC has placed Forest Park in the Marginal Risk category for severe thunderstorms tomorrow.
- TODAYNONENo severe risk
- TOMORROWMRGLMarginal Risk
- DAY 3TSTMGeneral Thunderstorms
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
Forest Park's warmest month is July (~76°F mean) and its coldest is January (~26°F). Rainfall peaks in May (4.1 inches) and bottoms out in February (1.5 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 26° | 1.5″ | 3 |
| February | 30° | 1.5″ | 3 |
| March | 40° | 1.9″ | 5 |
| April | 51° | 3.6″ | 7 |
| May | 62° | 4.1″ | 8 |
| June | 72° | 4.0″ | 8 |
| July | 76° | 3.5″ | 6 |
| August | 75° | 4.0″ | 6 |
| September | 68° | 2.8″ | 5 |
| October | 55° | 3.5″ | 6 |
| November | 42° | 2.4″ | 5 |
| December | 31° | 1.8″ | 4 |
Regional context
Forest Park 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 Forest Park?
- Forest Park's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Forest Park?
- May is the wettest month with about 4.1 inches of rain on average; the city receives roughly 34 inches annually.
- What is the warmest month in Forest Park?
- July is typically warmest, averaging about 76°F.
- What is the coldest month in Forest Park?
- January is typically coldest, averaging about 26°F.
- When can I start a vegetable garden in Forest Park?
- 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 Forest Park get?
- Forest Park averages about 68 rainy days per year.
- What hardiness zone is Forest Park?
- Forest Park'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
Forest Park, Illinois sits in a warm-summer humid continental climate zone. January means hover near 26°F while July averages 76°F — a 50°F seasonal swing.
Across the year, Forest Park receives about 34 inches of precipitation spread over roughly 68 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.