Hardly any U.S. towns see harsher January nights than Armstrong
In July the day’s top temperature is typically 82°. June is the wettest month here, with about 6.2 times the rain of January. Its yearly precipitation falls short of 84% of U.S. towns. Homes need heating from October to April, the months averaging under 50°.
A year in Armstrong at a glance
Each month’s typical high and low, and what it brings.
What stands out about Armstrong’s climate
Compared with towns across the U.S., with Armstrong’s place in Iowa beside it.
What a year in Armstrong feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 150 frost-free days a year
In half of years the last 32° night comes by May 4 and the first by October 1. Frost and day counts come from NOAA’s station at Swea City 5n, IA, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Armstrong’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −18°. 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 40 inches of snow a winter
Snow, measured at Swea City 5n, IA, falls mostly in January. Precipitation (rain plus melted snow) adds up to 32 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 93 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Armstrong
94% 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 Swea City 5n, IA.
Living with Armstrong’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
150 frost-free days in zone 5a. The last frost comes by May 4 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 1.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 0.3 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Armstrong from natural hazards, drought is the largest share (39%); heat waves, cold waves, winter storms and ice storms together are 30%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Armstrong and similar climates
TownRatings has no climate map of the towns around Armstrong yet.
Climates most like Armstrong’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 |
|---|---|---|---|---|
| Armstrong, IA | 7° | 82° | 32" | 40" |
| Menomonie, WI | 5° | 82° | 34" | 41" |
| Isanti, MN | 4° | 82° | 32" | 44" |
| Plattsburgh, NY | 9° | 81° | 35" | 50" |
| Wayne, NE | 11° | 85° | 29" | 32" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Armstrong averaged 1.1° warmer than the 1900s. The biggest change is in December (+2.5°).
A smaller shift than in 71% of 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 Armstrong compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Armstrong’s place among Iowa’s.
Armstrong weather by month
Highs, lows and precipitation from NOAA’s grid at Armstrong’s center; snow, wet days and snow on the ground from Swea City 5n, IA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 24° | 7° | 0.8" | 10.9" | 6 | 23 | 5° – 27° |
| February | 29° | 11° | 0.8" | 8.5" | 5 | 21 | 9° – 31° |
| March | 42° | 24° | 1.7" | 4.6" | 7 | 10 | 26° – 48° |
| April | 57° | 35° | 3.3" | 3.6" | 10 | 1 | 35° – 53° |
| May | 69° | 47° | 4.5" | 0.0" | 12 | 0 | 53° – 64° |
| June | 80° | 58° | 4.9" | 0.0" | 11 | 0 | 65° – 72° |
| July | 82° | 61° | 3.9" | 0.0" | 9 | 0 | 65° – 77° |
| August | 80° | 59° | 3.8" | 0.0" | 8 | 0 | 65° – 74° |
| September | 74° | 50° | 3.2" | 0.0" | 8 | 0 | 56° – 67° |
| October | 60° | 38° | 2.3" | 0.7" | 7 | 0 | 42° – 55° |
| November | 43° | 25° | 1.4" | 3.1" | 6 | 6 | 24° – 46° |
| December | 29° | 13° | 1.2" | 8.3" | 6 | 21 | 7° – 28° |
| Year | 56° | 36° | 31.9" | 39.7" | 93 | 82 |
How much a month can swing
A normal is an average. January swings the most: from 1991 to 2020 its average ranged from 5° to 27°. June is the most reliable, staying within 8°.
Where Armstrong’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 Armstrong’s center.
- Snow: Swea City 5n, IA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Swea City 5n, IA, 10 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 Armstrong’s climate
What is the weather like in Armstrong?
A typical July afternoon reaches 82°, a January night drops to 7°, and about 40 inches of snow falls in a normal winter. Colder January nights than 97% of U.S. towns; cooler July afternoons than 77% of U.S. towns.
How cold does it get in Armstrong in winter?
January nights average 7°. About 163 nights a year reach 32° or below and 28 reach 0° or below. In the coldest January of the last 30 years the month averaged 5°.
How much snow does Armstrong get?
About 40 inches in a normal winter at Swea City 5n, IA, most of it in January, with snow on the ground about 82 days a year.
How hot does it get in Armstrong?
July, with a typical high of 82° and a low of 61°. About 11 days a year reach 90° (Swea City 5n, IA).
When is the first and last frost in Armstrong?
In half of years the last spring frost (32°) comes by May 4 and the first fall frost by October 1, about 150 frost-free days, at Swea City 5n, IA.
What growing zone is Armstrong in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −18°.
What is the best time of year to visit Armstrong?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Armstrong getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 71% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Armstrong.
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.