Mills gets about 82 inches of snow a winter, more than 95% of U.S. towns
A typical July afternoon reaches 89°, a January night drops to 14°, and about 82 inches of snow falls in a normal winter.
A year in Mills at a glance
Each month’s typical high and low, and what it brings.
What stands out about Mills’ climate
Compared with towns across the U.S., with Mills’ place in Wyoming beside it.
What a year in Mills feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 117 frost-free days a year
In half of years the last 32° night comes by May 26 and the first by September 22. Frost and day counts come from NOAA’s station at Casper Natrona Co Airport, 5 miles from the town’s center, 110 ft higher.
The 2023 USDA map puts Mills’ center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −17°. 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 82 inches of snow a winter
Snow, measured at Casper 4.3 Wsw, WY, falls mostly in December. Precipitation (rain plus melted snow) adds up to 11 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 99 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Mills
94% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Casper Natrona Co Airport.
Living with Mills’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
117 frost-free days in zone 5a. The last frost comes by May 26 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 22.
Months with highs of 62–84° and lows of 40° or more: June and September. 0.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Mills from natural hazards, river flooding is the largest share (66%); heat waves, cold waves, winter storms and ice storms together are 14%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Mills and its neighbors
Every town next door is within a degree of Mills in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Mills’, 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 |
|---|---|---|---|---|
| Mills, WY | 14° | 89° | 11" | 82" |
| Heber, UT | 12° | 88° | 15" | 75" |
| Thornton, CO | 18° | 90° | 14" | 74" |
| Preston, ID | 14° | 89° | 15" | 52" |
| Billings, MT | 15° | 89° | 14" | 48" |
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 Mills averaged 1.7° warmer than the 1900s. The biggest change is in March (+4.0°).
A bigger shift than in 70% 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 Mills compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Mills’ place among Wyoming’s.
Mills weather by month
Highs, lows and precipitation from NOAA’s grid at Mills’ center; snow, wet days and snow on the ground from Casper 4.3 Wsw, WY. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 37° | 14° | 0.5" | 11.1" | 7 | 22 | 20° – 31° |
| February | 39° | 16° | 0.5" | 14.6" | 8 | 17 | 20° – 34° |
| March | 50° | 24° | 0.7" | 12.3" | 8 | 9 | 28° – 44° |
| April | 58° | 29° | 1.4" | 10.7" | 12 | 5 | 37° – 49° |
| May | 68° | 38° | 2.2" | 3.0" | 13 | 1 | 47° – 60° |
| June | 80° | 47° | 1.3" | 0.0" | 9 | 0 | 57° – 69° |
| July | 89° | 54° | 1.0" | 0.0" | 8 | 0 | 64° – 76° |
| August | 87° | 52° | 0.8" | 0.0" | 6 | 0 | 64° – 73° |
| September | 76° | 43° | 0.9" | 0.4" | 6 | 0 | 54° – 65° |
| October | 61° | 32° | 1.1" | 5.9" | 8 | 3 | 38° – 53° |
| November | 47° | 22° | 0.5" | 6.7" | 6 | 7 | 22° – 44° |
| December | 37° | 14° | 0.5" | 17.0" | 8 | 20 | 17° – 30° |
| Year | 61° | 32° | 11.3" | 81.7" | 99 | 84 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 22° to 44°. August is the most reliable, staying within 9°.
Where Mills’ 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 Mills’ center.
- Snow: Casper 4.3 Wsw, WY.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Casper Natrona Co Airport, 5 miles from the town’s center, 110 ft higher; 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 Mills’ climate
What is the weather like in Mills?
A typical July afternoon reaches 89°, a January night drops to 14°, and about 82 inches of snow falls in a normal winter. Colder January nights than 86% of U.S. towns; hotter July afternoons than 72% of U.S. towns.
How cold does it get in Mills in winter?
December nights average 14°. About 183 nights a year reach 32° or below and 15 reach 0° or below. In the coldest December of the last 30 years the month averaged 17°.
How much snow does Mills get?
About 82 inches in a normal winter at Casper 4.3 Wsw, WY, most of it in December, with snow on the ground about 84 days a year.
How hot does it get in Mills?
July, with a typical high of 89° and a low of 54°. About 38 days a year reach 90° and 1 reach 100° (Casper Natrona Co Airport).
When is the first and last frost in Mills?
In half of years the last spring frost (32°) comes by May 26 and the first fall frost by September 22, about 117 frost-free days, at Casper Natrona Co Airport.
What growing zone is Mills in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −17°.
What is the best time of year to visit Mills?
By one simple rule (highs of 62–84° and lows of 40° or more), June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Mills getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 70% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Mills.
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.