Grinnell, IA Weather & Climate Normals
What a normal year in Grinnell actually looks like
On the 30-year record NOAA keeps for Grinnell, IA, the comfort score comes out to 43/100, strongly seasonal: Comfortable weather is limited to a shorter window; summers, winters, or precipitation swing wide. Only 5 months a year land in the 55–75°F range this site treats as mild.
How much Grinnell's weather actually swings
Average temperatures in Grinnell run from 19°F in Jan up to 73°F in Jul, a 53.3°F seasonal swing, one of the widest gaps in this dataset.
Grinnell, month by month
| Month | Avg high | Avg low | Precip | Snow |
|---|---|---|---|---|
| Jan | 28°F | 10°F | 1.1in | 9in |
| Feb | 33°F | 14°F | 1.55in | 9.1in |
| Mar | 46°F | 25°F | 2.22in | 3.4in |
| Apr | 59°F | 35°F | 3.9in | 0.6in |
| May | 70°F | 47°F | 5.09in | 0in |
| Jun | 80°F | 58°F | 5.53in | 0in |
| Jul | 83°F | 62°F | 3.96in | 0in |
| Aug | 81°F | 59°F | 4.37in | 0in |
| Sep | 75°F | 50°F | 3.71in | 0in |
| Oct | 62°F | 38°F | 3.21in | 0.5in |
| Nov | 47°F | 26°F | 1.95in | 1.5in |
| Dec | 34°F | 16°F | 1.6in | 6.9in |
If you're timing a visit, May, Jun, Jul, Aug, and Sep are Grinnell's mildest stretch; if you're moving there, you should plan around Jan's cold instead.
How wet Grinnell actually gets
Over a typical year, Grinnell sees about 38.19in of precipitation a year across roughly 115 days with measurable rain or snow, with 31in of snow a year.
Grinnell against the rest of the country
Out of 4876 cities scored here, Grinnell comes in at 4074; within IA alone it ranks 37 of 85. Population is about 9,495.
Checking the actual forecast
These figures come from Grinnell 3 Sw, IA US, the NOAA station 1.6 miles from Grinnell, averaged over 30 years, not tomorrow's forecast.
More on how this is worked out
Why this uses the nearest NOAA station · How the comfort score is calculated