Photo: PopePompus · CC BY-SA 4.0Midwinter lows in Norwalk sink below those of 89% of U.S. towns
July afternoons average 85°. Only 72° separates winter nights from summer afternoons. It is a dry place: less rain and snow fall here than on 75% of U.S. towns. Plan time outside from May to June and August to October, when highs sit at 64–83°.
A year in Norwalk at a glance
Each month’s typical high and low, and what it brings.
What stands out about Norwalk’s climate
Compared with towns across the U.S., with Norwalk’s place in Iowa beside it.
What a year in Norwalk feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 184 frost-free days a year
In half of years the last 32° night comes by April 18 and the first by October 20. Frost and day counts come from NOAA’s station at Des Moines International Airport, 4 miles from the town’s center, at about the same height.
The 2023 USDA map puts Norwalk’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −12°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 37 inches of snow a winter
Snow, measured at Des Moines International Airport, is heaviest from January through February, about 10 inches a month. Precipitation (rain plus melted snow) adds up to 36 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 113 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Norwalk
85% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Des Moines International Airport.
Living with Norwalk’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
184 frost-free days in zone 5b. The last frost comes by Apr 18 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 20.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October. 5.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Norwalk from natural hazards, river flooding is the largest share (37%); heat waves, cold waves, winter storms and ice storms together are 19%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Norwalk and its neighbors
Every town next door is within a degree of Norwalk in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Norwalk’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Norwalk, IA | 13° | 85° | 36" | 37" |
| Rock Island, IL | 14° | 85° | 37" | 36" |
| Beloit, WI | 13° | 83° | 37" | 37" |
| Milan, MI | 17° | 84° | 34" | 39" |
| Sayre, PA | 17° | 84° | 37" | 35" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Norwalk averaged 0.4° warmer than the 1900s. The biggest change is in December (+2.0°).
A smaller shift than in all but 146 U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Norwalk compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Norwalk’s place among Iowa’s.
Norwalk weather by month
Highs, lows and precipitation from NOAA’s grid at Norwalk’s center; snow, wet days and snow on the ground from Des Moines International Airport. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 31° | 13° | 0.9" | 9.4" | 8 | 18 | 13° – 35° |
| February | 36° | 17° | 1.2" | 10.2" | 8 | 15 | 16° – 38° |
| March | 49° | 29° | 2.0" | 4.4" | 10 | 5 | 31° – 54° |
| April | 62° | 40° | 3.8" | 1.2" | 12 | 1 | 42° – 57° |
| May | 72° | 51° | 5.2" | 0.2" | 13 | 0 | 56° – 69° |
| June | 82° | 61° | 5.1" | 0.0" | 12 | 0 | 68° – 75° |
| July | 85° | 65° | 4.1" | 0.0" | 10 | 0 | 70° – 82° |
| August | 83° | 62° | 4.1" | 0.0" | 9 | 0 | 68° – 78° |
| September | 77° | 54° | 3.5" | 0.0" | 8 | 0 | 59° – 70° |
| October | 64° | 42° | 2.6" | 0.5" | 9 | 0 | 46° – 58° |
| November | 49° | 30° | 1.8" | 2.7" | 8 | 2 | 30° – 50° |
| December | 36° | 19° | 1.4" | 7.9" | 8 | 10 | 12° – 35° |
| Year | 60° | 40° | 35.6" | 36.5" | 113 | 52 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 12° to 35°. June is the most reliable, staying within 7°.
Where Norwalk’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Norwalk’s center.
- Snow: Des Moines International Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Des Moines International Airport, 4 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Norwalk’s climate
What is the weather like in Norwalk?
A typical July afternoon reaches 85°, a January night drops to 13°, and about 37 inches of snow falls in a normal winter. Colder January nights than 89% of U.S. towns; hotter July afternoons than 51% of U.S. towns.
How cold does it get in Norwalk in winter?
January nights average 13°. About 128 nights a year reach 32° or below and 10 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How much snow does Norwalk get?
About 37 inches in a normal winter at Des Moines International Airport, heaviest from January through February, about 10 inches a month, with snow on the ground about 52 days a year.
How hot does it get in Norwalk?
July, with a typical high of 85° and a low of 65°. About 22 days a year reach 90° (Des Moines International Airport).
When is the first and last frost in Norwalk?
In half of years the last spring frost (32°) comes by April 18 and the first fall frost by October 20, about 184 frost-free days, at Des Moines International Airport.
What growing zone is Norwalk in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −12°.
What is the best time of year to visit Norwalk?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Norwalk getting warmer?
Yes: 1991–2020 averaged 0.4° warmer than 1901–2000 on NOAA’s grid. A smaller shift than all but 146 U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Norwalk.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.