Green River, Wyoming climate: Normal weather by month, frost dates and records
Green River's normal year runs from 8°F January nights to 87°F July afternoons, with 10.3 inches of precipitation and 39 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.7°C, January lows of −13°C, July highs of 30°C, 262 mm of precipitation a year.
- NOAA stationGreen River
- Station IDUSC00484065
- Location41.52°N 109.47°W
- Elevation6,160 ft (1,878 m)
- Population11,474
On October 14, the normal high in Green River is 62°F and the normal low 31°F, and the chance of measurable rain or snow is 20%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Green River.
- Jan 31° 8°
- Feb 36° 13°
- Mar 47° 23°
- Apr 56° 29°
- May 66° 38°
- Jun 78° 46°
- Jul 87° 53°
- Aug 85° 51°
- Sep 76° 41°
- Oct 61° 30°
- Nov 44° 19°
- Dec 32° 10°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Green River each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 8°F. The most precipitation falls in May (1.67 in), the least in July (0.49 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 31°F | 8°F | 19.6°F | 0.69 | 6.3 | 5 | <1 | 31 | 9 h 30 min |
| February | 36°F | 13°F | 24.5°F | 0.51 | 7.6 | 5 | <1 | 28 | 10 h 40 min |
| March | 47°F | 23°F | 34.8°F | 0.84 | 5.4 | 6 | <1 | 29 | 11 h 50 min |
| April | 56°F | 29°F | 42.8°F | 1.32 | 3.9 | 7 | <1 | 22 | 13 h 20 min |
| May | 66°F | 38°F | 51.9°F | 1.67 | 0.9 | 9 | <1 | 8 | 14 h 30 min |
| June | 78°F | 46°F | 61.8°F | 0.92 | 0.0 | 5 | 4 | 1 | 15 h 10 min |
| July | 87°F | 53°F | 69.7°F | 0.49 | 0.0 | 5 | 14 | <1 | 14 h 50 min |
| August | 85°F | 51°F | 67.9°F | 0.64 | 0.0 | 5 | 10 | <1 | 13 h 50 min |
| September | 76°F | 41°F | 58.3°F | 0.87 | 0.3 | 6 | 1 | 4 | 12 h 30 min |
| October | 61°F | 30°F | 45.5°F | 1.04 | 2.4 | 6 | <1 | 20 | 11 h 10 min |
| November | 44°F | 19°F | 31.4°F | 0.69 | 5.0 | 5 | <1 | 28 | 9 h 50 min |
| December | 32°F | 10°F | 20.9°F | 0.63 | 6.7 | 6 | <1 | 31 | 9 h 10 min |
| Year (annual) | 58°F | 30°F | 44.1°F | 10.31 | 38.5 | 71 | 30 | 200 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −13°C | −6.9°C | 18 mm | 16 cm |
| February | 2°C | −11°C | −4.2°C | 13 mm | 19 cm |
| March | 8°C | −5°C | 1.6°C | 21 mm | 14 cm |
| April | 14°C | −1°C | 6.0°C | 34 mm | 10 cm |
| May | 19°C | 3°C | 11.1°C | 42 mm | 2 cm |
| June | 26°C | 8°C | 16.6°C | 23 mm | 0 cm |
| July | 30°C | 12°C | 20.9°C | 12 mm | 0 cm |
| August | 29°C | 10°C | 19.9°C | 16 mm | 0 cm |
| September | 24°C | 5°C | 14.6°C | 22 mm | 1 cm |
| October | 16°C | −1°C | 7.5°C | 26 mm | 6 cm |
| November | 7°C | −7°C | −0.3°C | 18 mm | 13 cm |
| December | 0°C | −12°C | −6.2°C | 16 mm | 17 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00484065; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Green River?
Normal highs sit between 65°F and 85°F in May, June, August and September. Of those, June has the fewest days with rain (5).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00484065.
When is the last frost in Green River?
In Green River, the last spring frost (32°F) comes after May 24 in half of years and after June 10 in one year in ten; the first autumn frost comes before September 22 in half of years and before September 7 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 241 year in 10 after June 10; 9 in 10 after May 7
- First autumn frost, half of years before
- September 221 year in 10 before September 7; 9 in 10 before October 6
NOAA puts the median frost-free season at 120 days, and the season without a hard freeze (28°F) at 146 days.
A hard freeze (28°F) comes after May 9 in half of springs and before October 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Green River in zone 5a in ZIP code 82935, the nearest ZIP area.
Frost dates for every NOAA station in Wyoming · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00484065; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Green River?
In a normal year in Green River, 30 days a year reach 90°F, 200 nights fall to 32°F or colder and 71 days bring measurable precipitation.
- Days at 90°F or more
- 30a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 200a normal year
- Days that stay below freezing
- 43high of 32°F or less
- Days with 0.01 inch of precipitation
- 71a normal year
- Days with 1 inch of snow or more
- 15a normal year
The highest temperature in this station's record (since 1897) is 104°F, on July 8, 1954; the lowest is −42°F, on December 31, 1978.
The wettest calendar year on that record is 2016, with 15.72 in; the snowiest season is 2016–17, with 77.1 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00484065; records: ACIS (NOAA Regional Climate Centers), station USC00484065. Records use complete months only; a month missing more than three days is left out.
How sunny is Green River?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Green River, 4.7 kWh per square metre a day. September is the sunniest month (86%) and December the cloudiest (68%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 72% | 2.2 |
| February | 73% | 3.1 |
| March | 73% | 4.3 |
| April | 75% | 5.7 |
| May | 78% | 6.7 |
| June | 84% | 7.6 |
| July | 84% | 7.3 |
| August | 84% | 6.4 |
| September | 86% | 5.3 |
| October | 81% | 3.8 |
| November | 76% | 2.5 |
| December | 68% | 1.8 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Green River need?
A normal year in Green River brings 7,939 heating degree days, 48% more than the median U.S. place (5,373), and 350 cooling degree days, 61% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,997 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,409 | 0 |
| February | 1,134 | 0 |
| March | 936 | 0 |
| April | 665 | 0 |
| May | 408 | 2 |
| June | 140 | 44 |
| July | 23 | 170 |
| August | 32 | 120 |
| September | 214 | 13 |
| October | 605 | 0 |
| November | 1,007 | 0 |
| December | 1,367 | 0 |
| Year (annual) | 7,939 | 350 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00484065. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Green River been warmer than normal lately?
2025 averaged 48.3°F, 4.2°F above the 1991-2020 normal of 44.1°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 47.0°F | +2.9°F | 10.09 | 44.1 |
| 2023 | 42.7°F | −1.4°F | 14.21 | 57.5 |
| 2024 | 46.6°F | +2.5°F | 10.74 | 47.1 |
| 2025 | 48.3°F | +4.2°F | 8.98 | 22.9 |
Over 65 complete years from 1905 to 2025, the station's annual mean temperature rose at a fitted 3.5°F per century (+0.19°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00484065; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Green River's climate compare?
Green River is warmer than 33 of the other 70 places with their own NOAA record in Wyoming, and wetter than 21. Across the 7,247 U.S. stations with normals, its annual mean of 44.1°F is warmer than 16%.
In the Köppen classification computed from these normals, Green River is BSk: cold semi-arid steppe. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Green River share this climate record?
3 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Purple Sage, WY676 people · 8 mi E
- James Town, WY447 people · 5 mi NW
- Clearview Acres, WY236 people · 11 mi NE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Green River's climate
What is the coldest month in Green River?
January, with a normal high of 31°F and a normal low of 8°F. The warmest is July (87°F by day, 53°F at night).
Does it snow in Green River?
Yes: 39 inches in a normal year, falling on 26 days with 0.1 inch or more, the most in February (7.6 inches).
What is the rainiest month in Green River?
May, with 1.67 in of precipitation in a normal year; the driest is July with 0.49 in.
What plant hardiness zone is Green River in?
The USDA's 2023 map puts Green River in zone 5a in ZIP code 82935, the nearest ZIP area.
How late can frost come in Green River?
In half of years the last 32°F night comes after May 24; in one year in ten it comes after June 10. Waiting until June 10 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wyoming climateThe statewide normals and every place in the state
- Buckboard Marina, WY20 miles from this station, 43.9°F a year
- Rock Springs, WY22 miles from this station, 43.7°F a year
- Church Buttes Gas Plant, WY33 miles from this station, 43.2°F a year
- Manila, UT39 miles from this station, 44.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made