Photo: Vasiliymeshko · CC BY-SA 4.0Few U.S. towns get less rain and snow than Rock Springs: 9 inches a year
Midwinter brings lows of about 9°. Seasons differ by 79°, from the coldest nights to the warmest afternoons. Winter nights are cold: in January they are colder than in 95% of U.S. towns. Homes need heating from October to April, the months averaging under 50°.
A year in Rock Springs at a glance
Each month’s typical high and low, and what it brings.
What stands out about Rock Springs’ climate
Compared with towns across the U.S., with Rock Springs’ place in Wyoming beside it.
What a year in Rock Springs feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 121 frost-free days a year
In half of years the last 32° night comes by May 24 and the first by September 24. Frost and day counts come from NOAA’s station at Rock Springs Fire Dept, WY, 1.5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Rock Springs’ 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 31 inches of snow a winter
Snow, measured at Rock Springs Fire Dept, WY, falls mostly in January and December. Precipitation (rain plus melted snow) adds up to 9 inches a year; May is the wettest month and November the driest. Rain or snow falls on about 62 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Rock Springs
96% 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 Rock Springs Fire Dept, WY.
Living with Rock Springs’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
121 frost-free days in zone 5a. The last frost comes by May 24 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 24.
Months with highs of 62–84° and lows of 40° or more: June and September. 23 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Rock Springs from natural hazards, river flooding is the largest share (71%); heat waves, cold waves, winter storms and ice storms together are 18%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Rock Springs and similar climates
TownRatings has no climate map of the towns around Rock Springs yet.
Climates most like Rock Springs’, 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 |
|---|---|---|---|---|
| Rock Springs, WY | 9° | 87° | 9" | 31" |
| Salida, CO | 10° | 85° | 8" | 37" |
| Havre, MT | 6° | 85° | 13" | 41" |
| Taos, NM | 11° | 84° | 13" | 28" |
| Ephraim, UT | 14° | 89° | 12" | 20" |
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 Rock Springs averaged 1.4° warmer than the 1900s. The biggest change is in March (+3.5°).
A bigger shift than in 52% 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 Rock Springs compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Rock Springs’ place among Wyoming’s.
Rock Springs weather by month
Highs, lows and precipitation from NOAA’s grid at Rock Springs’ center; snow, wet days and snow on the ground from Rock Springs Fire Dept, WY. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 32° | 9° | 0.4" | 6.1" | 4 | 14 | 12° – 29° |
| February | 36° | 12° | 0.5" | 5.8" | 5 | 8 | 12° – 31° |
| March | 47° | 22° | 0.6" | 4.4" | 4 | 3 | 26° – 40° |
| April | 56° | 28° | 1.0" | 1.9" | 6 | 1 | 37° – 48° |
| May | 66° | 37° | 1.3" | 0.5" | 9 | 0 | 45° – 56° |
| June | 78° | 45° | 0.8" | 0.0" | 5 | 0 | 54° – 66° |
| July | 87° | 52° | 0.5" | 0.0" | 4 | 0 | 61° – 74° |
| August | 85° | 50° | 0.8" | 0.0" | 5 | 0 | 63° – 71° |
| September | 74° | 40° | 1.0" | 0.0" | 6 | 0 | 53° – 61° |
| October | 60° | 29° | 1.0" | 2.3" | 5 | 1 | 36° – 51° |
| November | 43° | 18° | 0.4" | 3.8" | 4 | 4 | 21° – 39° |
| December | 32° | 9° | 0.4" | 6.5" | 6 | 13 | 15° – 28° |
| Year | 58° | 29° | 8.6" | 31.3" | 62 | 44 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 12° to 31°. September is the most reliable, staying within 8°.
Where Rock Springs’ 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 Rock Springs’ center.
- Snow: Rock Springs Fire Dept, WY (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Rock Springs Fire Dept, WY, 1.5 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 Rock Springs’ climate
What is the weather like in Rock Springs?
A typical July afternoon reaches 87°, a January night drops to 9°, and about 31 inches of snow falls in a normal winter. Colder January nights than 95% of U.S. towns; hotter July afternoons than 64% of U.S. towns.
How cold does it get in Rock Springs in winter?
January nights average 9°. About 184 nights a year reach 32° or below and 11 reach 0° or below. In the coldest January of the last 30 years the month averaged 12°.
How much snow does Rock Springs get?
About 31 inches in a normal winter at Rock Springs Fire Dept, WY, most of it in January and December, with snow on the ground about 44 days a year.
How hot does it get in Rock Springs?
July, with a typical high of 87° and a low of 52°. About 15 days a year reach 90° (Rock Springs Fire Dept, WY).
When is the first and last frost in Rock Springs?
In half of years the last spring frost (32°) comes by May 24 and the first fall frost by September 24, about 121 frost-free days, at Rock Springs Fire Dept, WY.
What growing zone is Rock Springs 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 Rock Springs?
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 Rock Springs getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Rock Springs.
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.