Grinnell, United States experiences average highs of 16°C (61°F) and lows of 6°C (43°F) throughout the year. Rainfall is moderate, averaging about 9 rainy days per month. Sunshine is abundant, averaging about 9 hours per day. Average highs have stayed broadly stable across the available records.
Grinnell, United States Weather & Climate 2026
Monthly climate averages for Grinnell, United States. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: Jan–Dec 
Wetter season: Mar–Oct At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
5.5/10
Best: May, June, July, August, September
UV Index
5
Low
Temperature 16°C / 6°C
Feels Like 14°C / 3°C
Rainy Days 9
Rainfall 80 mm
Sunshine 9 h
Humidity 69%
Wind Speed 22 km/h
Dew Point 5°C
Snow Days 5 days
Frost Days 17 days
Hottest Month
29°C
July
Avg Low20°C
Rain10days
Coldest Month
-9°C
January
Avg High-1°C
Rain7days
Driest Month
6days
February
Avg High2°C
Avg Low-8°C
Windiest Month
26 km/h
April (Gusts 49)
Worst Time to Visit
Consider avoiding January, February, March, December due to very cold temperatures.
Sun Position
Sunrise 05:37
Daylight 15.2h
Sunset 20:48
Live conditions—
Grinnell on the map · live conditions
Grinnell, United States
- Continent
- Americas
- Country
- United States
- City
- Grinnell
- Population
- 9.1K
- Elevation
- 309 m
- Coordinates
- 41.74°, -92.72°
Seasonal Breakdown
Spring
Mar–May
Avg High 16°C
Avg Low 5°C
Rain 11 days/mo
1/3 best months
Summer
Jun–Aug
Avg High 28°C
Avg Low 19°C
Rain 9 days/mo
3/3 best months
Autumn
Sep–Nov
Avg High 18°C
Avg Low 8°C
Rain 8 days/mo
1/3 best months
Winter
Dec–Feb
Avg High 1°C
Avg Low -8°C
Rain 6 days/mo
Climate Charts
Based on historical averages (2016–2025)
Monthly Temperatures
HighLowShaded bands show the typical range across the available yearly records.
Line chart showing monthly temperatures. Jan: -1°C / -9°C . Feb: 2°C / -8°C . Mar: 10°C / 0°C . Apr: 16°C / 5°C . May: 22°C / 12°C . Jun: 28°C / 18°C . Jul: 29°C / 20°C . Aug: 28°C / 19°C . Sep: 26°C / 16°C . Oct: 18°C / 8°C . Nov: 10°C / 1°C . Dec: 3°C / -5°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 41 mm. Feb: 35 mm. Mar: 80 mm. Apr: 96 mm. May: 136 mm. Jun: 105 mm. Jul: 94 mm. Aug: 79 mm. Sep: 92 mm. Oct: 107 mm. Nov: 49 mm. Dec: 41 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 75%. Feb: 69%. Mar: 66%. Apr: 63%. May: 68%. Jun: 67%. Jul: 73%. Aug: 72%. Sep: 68%. Oct: 64%. Nov: 68%. Dec: 71%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 23 km/h . Feb: 24 km/h . Mar: 25 km/h . Apr: 26 km/h . May: 22 km/h . Jun: 20 km/h . Jul: 17 km/h . Aug: 18 km/h . Sep: 20 km/h . Oct: 23 km/h . Nov: 23 km/h . Dec: 23 km/h .
Sunshine
Sunshine
Sunshine: Jan: 6h. Feb: 7h. Mar: 8h. Apr: 9h. May: 10h. Jun: 12h. Jul: 12h. Aug: 11h. Sep: 10h. Oct: 8h. Nov: 7h. Dec: 6h.
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 5. Apr: UV 6. May: UV 7. Jun: UV 7. Jul: UV 7. Aug: UV 7. Sep: UV 6. Oct: UV 4. Nov: UV 3. Dec: UV 2.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Snow Days
Snow DaysSnowfall
Snow Days: Jan: 9 days. Feb: 7 days. Mar: 4 days. Apr: 2 days. May: 0 days. Jun: 0 days. Jul: 0 days. Aug: 0 days. Sep: 0 days. Oct: 1 days. Nov: 2 days. Dec: 7 days.
Climate Trends
Average highs have stayed broadly stable across the available records. Average rainfall has remained broadly steady.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Jul 2025 · 29°C | Jul · 29°C |
| Coldest month | Jan 2025 · -9°C | Jan · -9°C |
| Wettest month | Jul 2025 · 230 mm | May · 136 mm |
| Windiest month | Mar 2025 · 28 km/h | Apr · 26 km/h |
Month-by-Month Weather Table
January
Poor 
February
Poor March
Poor April
Fair May best
Excellent June best
Excellent July best
Excellent August best
Excellent September best
Excellent October
Good November
Poor December
Poor | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | -1°C / -9°C | -6°C / -15°C | 7days (41 mm) Good | 5.6h Fair | 75% Muggy | 2.5 Moderate | Poor | View Details |
| February | 2°C / -8°C | -3°C / -13°C | 6days (35 mm) Good | 7.4h Good | 69% Muggy | 3.7 Moderate | Poor | View Details |
| March | 10°C / 0°C | 6°C / -5°C | 10days (80 mm) Wet | 7.7h Good | 66% Muggy | 4.7 Moderate | Poor | View Details |
| April | 16°C / 5°C | 13°C / 1°C | 11days (96 mm) Wet | 8.8h Good | 63% Muggy | 5.6 High | Fair | View Details |
| May best | 22°C / 12°C | 21°C / 9°C | 13days (136 mm) Wet | 9.8h Good | 68% Muggy | 6.9 High | Excellent | View Details |
| June best | 28°C / 18°C | 30°C / 18°C | 10days (105 mm) Wet | 12.1h Excellent | 67% Muggy | 7.2 Very High | Excellent | View Details |
| July best | 29°C / 20°C | 32°C / 21°C | 10days (94 mm) Wet | 12h Excellent | 73% Muggy | 7.2 Very High | Excellent | View Details |
| August best | 28°C / 19°C | 30°C / 19°C | 8days (79 mm) Wet | 11.2h Excellent | 72% Muggy | 6.6 High | Excellent | View Details |
| September best | 26°C / 16°C | 26°C / 15°C | 8days (92 mm) Wet | 9.7h Good | 68% Muggy | 5.6 High | Excellent | View Details |
| October | 18°C / 8°C | 15°C / 5°C | 9days (107 mm) Wet | 7.6h Good | 64% Muggy | 4.1 Moderate | Good | View Details |
| November | 10°C / 1°C | 6°C / -4°C | 6days (49 mm) Good | 6.5h Fair | 68% Muggy | 2.7 Moderate | Poor | View Details |
| December | 3°C / -5°C | -1°C / -10°C | 6days (41 mm) Good | 5.7h Fair | 71% Muggy | 2.1 Moderate | Poor | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Grinnell are May, June, July, August, September, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Grinnell, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Grinnell is July, with average daytime highs of 29°C (84°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Grinnell is January, with average overnight lows of -9°C (15°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Grinnell is May, averaging 136mm of precipitation across 13 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Grinnell runs through May, April, March, June, with the heaviest rainfall in May. Based on 10-year averages for Grinnell.
Grinnell receives approximately 104 sunshine hours per year. The sunniest month is June with around 12 hours. Based on climate data for Grinnell.
The least favorable months to visit Grinnell are January, February, March, December, primarily due to very cold temperatures. For the best conditions, consider May, June, July, August, September instead.
The annual average UV index in Grinnell is 5, classified as moderate. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Grinnell is 69%, classified as moderate. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Yes, Grinnell receives snow. Months with snowfall average 5 snow days and 8 cm (3 in) of accumulation, with about 17 frost days during winter.
Average wind speeds in Grinnell are 22 km/h (14 mph). The windiest month is April with peak winds reaching 26 km/h (16 mph) (gusts up to 49 km/h / 31 mph).
Grinnell averages 5 clear-sky days per month with overall cloud cover around 55%. The clearest skies occur in September.
The annual average dew point in Grinnell is 5°C (41°F), which feels dry and comfortable. Outdoor activities are comfortable year-round from a humidity standpoint.
Grinnell has a Hot-Summer Continental climate, classified as Dfa under the Köppen system. Continental climates experience extreme temperature ranges — hot summers and cold, snowy winters.
The 'feels like' temperature in Grinnell ranges from 3°C (37°F) to 14°C (57°F) on average. Wind chill makes winters feel noticeably colder than the actual temperature — layered clothing is recommended.
Yes, June is a great time to visit Grinnell. It earns a climate score of 8.7/10 with Excellent.
For June in Grinnell, pack Umbrella, Waterproof jacket, Breathable clothing, Sunscreen (SPF 30+), Sun hat. With average highs of 28°C (82°F) and 10 rainy days, these essentials will keep you comfortable.
Data Source
Climate data derived from ERA5 reanalysis (ECMWF), averaged over 2016–2025. Sea surface temperature from marine reanalysis data. Climate scores and seasonal estimates are computed by WorldStats.
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