Ottumwa, IA climate
Ottumwa has cold winters and warm summers. A typical July afternoon reaches 86°, a January night drops to 14°, and about 24 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Ottumwa feels like
Winter
Spring
Summer
Fall
Ottumwa weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 32° | 14° | 1.2" | 7.1" | 7 | 18 | 15° – 35° |
| February | 37° | 18° | 1.5" | 5.8" | 7 | 9 | 16° – 38° |
| March | 50° | 29° | 2.2" | 3.0" | 10 | 4 | 32° – 54° |
| April | 63° | 40° | 3.8" | 1.4" | 12 | 1 | 44° – 57° |
| May | 73° | 51° | 5.0" | 0 | 13 | 0 | 56° – 70° |
| June | 82° | 61° | 5.1" | 0 | 11 | 0 | 68° – 75° |
| July | 86° | 65° | 4.0" | 0 | 9 | 0 | 69° – 82° |
| August | 84° | 62° | 4.2" | 0 | 9 | 0 | 67° – 78° |
| September | 77° | 54° | 3.5" | 0 | 8 | 0 | 59° – 71° |
| October | 65° | 42° | 2.8" | 0.5" | 9 | 0 | 47° – 59° |
| November | 50° | 30° | 2.1" | 1.6" | 8 | 2 | 32° – 50° |
| December | 37° | 20° | 1.5" | 4.2" | 7 | 5 | 13° – 38° |
| Year | 61° | 40° | 36.9" | 23.6" | 109 | 38 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Ottumwa
Ottumwa gets 37 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 109 days a year. Snow covers the ground about 38 days of the year.
About 172 frost-free days a year
In half of years the last 32° night comes by April 23 and the first one by October 14. That leaves about 172 frost-free days for gardens, shorter than 58% of U.S. towns.
Heating and cooling a home in Ottumwa
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Ottumwa, 86% of that work is heating and 14% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How Ottumwa compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Ottumwa averaged 0.6° warmer than the 1900s. The biggest change is in December (+2.3°). The shift is smaller than in 93% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Ottumwa’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 13° to 38°. June is the most reliable, staying within 7°.
Common questions about Ottumwa’s climate
What is the coldest month in Ottumwa?
January, with a typical high of 32° and a low of 14°.
What is the hottest month in Ottumwa?
July, with a typical high of 86° and a low of 65°. About 19 days a year reach 90°.
How much snow does Ottumwa get?
About 24 inches in a normal winter, most of it in January.
When is the first frost in Ottumwa?
In half of years the first 32° night comes by October 14, and the last spring frost by April 23.
What is the rainiest month in Ottumwa?
June, with 5.1 inches of rain and melted snow. The year totals 37 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Ottumwa itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Ottumwa Industrial Airport, IA (6 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.