Grinnell, Iowa Weather
Prairie lightning bugs rise. Day 77 of spring. Read this microseason across nine climate regions →
Grinnell weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Partly Cloudy——80°57°—
- ThursdayJun 4Heavy Drizzle55%0.07″84°61°+4°
- FridayJun 5Thunderstorm69%1.1″82°66°-2°
- SaturdayJun 6Showers60%—84°63°+2°
- SundayJun 7Showers45%—84°69°0°
- MondayJun 8Light Showers55%—81°68°-3°
- TuesdayJun 9Foggy30%—88°69°+7°
Ozone at AQI 46. AQI up 31 in the last 6 hours — air quality is degrading. Overcast through the UV peak window (cloud cover ~74%) — 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 46. Overcast through the UV peak window (cloud cover ~74%) — afternoon ozone should stay flat.
- Present
- AQI 46
- UV peak
- 0.1 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 6
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
- 4:46 AM
- Moonset
- 2:08 PM
- In sign
- ♑︎ Capricorn
Prairie lightning bugs rise
Grinnell at a glance
- Today vs. normal: 72°F — typical for the season
- 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 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 — Grinnell
SPC has placed Grinnell in the Slight Risk category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3SLGTSlight Risk
Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.
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.