Greybull, Wyoming climate: Normal weather by month, frost dates and records
Greybull's normal year runs from 6°F January nights to 91°F July afternoons, with 5.5 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.9°C, January lows of −14°C, July highs of 33°C, 141 mm of precipitation a year.
- NOAA stationGreybull S Big Horn Airport
- Station IDUSW00024048
- Location44.52°N 108.08°W
- Elevation3,933 ft (1,199 m)
- Population1,715
On October 23, the normal high in Greybull is 56°F and the normal low 30°F, and the chance of measurable rain or snow is 15%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Greybull.
- Jan 29° 6°
- Feb 36° 12°
- Mar 51° 25°
- Apr 60° 33°
- May 70° 44°
- Jun 81° 53°
- Jul 91° 58°
- Aug 89° 56°
- Sep 77° 45°
- Oct 60° 33°
- Nov 44° 19°
- Dec 31° 8°
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 Greybull each month?
July is the warmest month, with normal highs of 91°F; January the coldest, with normal lows of 6°F. The most precipitation falls in May (1.33 in), the least in December (0.11 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 29°F | 6°F | 17.5°F | 0.15 | 3 | <1 | 31 | 9 h 10 min |
| February | 36°F | 12°F | 23.6°F | 0.12 | 3 | <1 | 28 | 10 h 30 min |
| March | 51°F | 25°F | 37.9°F | 0.22 | 3 | <1 | 26 | 11 h 50 min |
| April | 60°F | 33°F | 46.7°F | 0.53 | 6 | <1 | 13 | 13 h 30 min |
| May | 70°F | 44°F | 57.0°F | 1.33 | 9 | 1 | 2 | 14 h 50 min |
| June | 81°F | 53°F | 67.0°F | 1.08 | 7 | 7 | <1 | 15 h 30 min |
| July | 91°F | 58°F | 74.9°F | 0.16 | 4 | 23 | <1 | 15 h 10 min |
| August | 89°F | 56°F | 72.3°F | 0.23 | 4 | 18 | <1 | 14 h 10 min |
| September | 77°F | 45°F | 60.9°F | 0.83 | 5 | 4 | 1 | 12 h 40 min |
| October | 60°F | 33°F | 46.5°F | 0.60 | 6 | <1 | 16 | 11 h |
| November | 44°F | 19°F | 31.2°F | 0.19 | 3 | <1 | 28 | 9 h 40 min |
| December | 31°F | 8°F | 19.3°F | 0.11 | 2 | <1 | 31 | 8 h 50 min |
| Year (annual) | 60°F | 33°F | 46.2°F | 5.55 | 54 | 53 | 177 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −14°C | −8.1°C | 4 mm |
| February | 2°C | −11°C | −4.7°C | 3 mm |
| March | 11°C | −4°C | 3.3°C | 6 mm |
| April | 16°C | 1°C | 8.2°C | 13 mm |
| May | 21°C | 6°C | 13.9°C | 34 mm |
| June | 27°C | 11°C | 19.4°C | 27 mm |
| July | 33°C | 15°C | 23.8°C | 4 mm |
| August | 32°C | 13°C | 22.4°C | 6 mm |
| September | 25°C | 7°C | 16.1°C | 21 mm |
| October | 16°C | 1°C | 8.1°C | 15 mm |
| November | 6°C | −7°C | −0.4°C | 5 mm |
| December | −1°C | −13°C | −7.1°C | 3 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Greybull's own co-op station Greybull station does: 19 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024048; 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 Greybull?
Normal highs sit between 65°F and 85°F in May, June and September. Of those, September 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 USW00024048.
When is the last frost in Greybull?
In Greybull, the last spring frost (32°F) comes after May 4 in half of years and after May 18 in one year in ten; the first autumn frost comes before October 1 in half of years and before September 18 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 41 year in 10 after May 18; 9 in 10 after April 22
- First autumn frost, half of years before
- October 11 year in 10 before September 18; 9 in 10 before October 14
NOAA puts the median frost-free season at 149 days, and the season without a hard freeze (28°F) at 170 days.
A hard freeze (28°F) comes after April 24 in half of springs and before October 13 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Greybull in zone 4b in ZIP code 82426, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Greybull's NOAA station is in zone 4b: the coldest night of a typical year reaches −22°F (21 complete years).
Frost dates for every NOAA station in Wyoming · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00024048; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. 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 Greybull?
In a normal year in Greybull, 53 days a year reach 90°F (7 of them 100°F or more), 177 nights fall to 32°F or colder and 54 days bring measurable precipitation.
- Days at 90°F or more
- 53a normal year
- Days at 100°F or more
- 7a normal year
- Nights at 32°F or colder
- 177a normal year
- Days that stay below freezing
- 52high of 32°F or less
- Days with 0.01 inch of precipitation
- 54a normal year
The highest temperature in this station's record (since 1998) is 108°F, on June 15, 2021; the lowest is −37°F, on January 27, 2009.
The wettest calendar year on that record is 2011, with 9.34 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00024048; records: ACIS (NOAA Regional Climate Centers), station USW00024048. Records use complete months only; a month missing more than three days is left out.
How sunny is Greybull?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Greybull, 4.4 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (65%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 71% | 1.8 |
| February | 72% | 2.8 |
| March | 74% | 4.0 |
| April | 74% | 5.3 |
| May | 75% | 6.3 |
| June | 82% | 7.2 |
| July | 87% | 7.3 |
| August | 85% | 6.2 |
| September | 83% | 4.8 |
| October | 76% | 3.2 |
| November | 72% | 2.0 |
| December | 65% | 1.4 |
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 Greybull need?
A normal year in Greybull brings 7,546 heating degree days, 40% more than the median U.S. place (5,373), and 743 cooling degree days, 18% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,684 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,474 | 0 |
| February | 1,158 | 0 |
| March | 840 | 0 |
| April | 550 | 1 |
| May | 271 | 23 |
| June | 62 | 122 |
| July | 4 | 309 |
| August | 15 | 241 |
| September | 169 | 46 |
| October | 575 | 2 |
| November | 1,014 | 0 |
| December | 1,415 | 0 |
| Year (annual) | 7,546 | 743 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024048. 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 Greybull been warmer than normal lately?
2025 averaged 47.9°F, 1.7°F above the 1991-2020 normal of 46.2°F. 3 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 48.0°F | +1.8°F | 3.88 |
| 2024 | 48.9°F | +2.6°F | 6.51 |
| 2025 | 47.9°F | +1.7°F | 7.07 |
Source: observed years: ACIS, station USW00024048. A year counts only with all twelve months complete.
How does Greybull's climate compare?
Greybull is warmer than 53 of the other 70 places with their own NOAA record in Wyoming, and wetter than 1. Across the 7,247 U.S. stations with normals, its annual mean of 46.2°F is warmer than 24%.
In the Köppen classification computed from these normals, Greybull is BWk: cold desert. 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.
What do Greybull's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Greybull. This page uses Greybull S Big Horn Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Greybull station USC00484080 | 2 mi SE | 3,787 ft | 45.0°F | 2°F | 91°F | 7.2 | 19 | May 11 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Greybull's climate
What is the coldest month in Greybull?
January, with a normal high of 29°F and a normal low of 6°F. The warmest is July (91°F by day, 58°F at night).
Does it snow in Greybull?
Yes. NOAA publishes no 1991-2020 snowfall normal for Greybull's NOAA station; Greybull's own co-op station Greybull station records 19 inches of snow in a normal year.
What is the rainiest month in Greybull?
May, with 1.33 in of precipitation in a normal year; the driest is December with 0.11 in.
What plant hardiness zone is Greybull in?
The USDA's 2023 map puts Greybull in zone 4b in ZIP code 82426, the nearest ZIP area. By the same method at Greybull's NOAA station, the coldest night of a typical year reaches −22°F (21 years, 1991-2020): zone 4b.
How late can frost come in Greybull?
In half of years the last 32°F night comes after May 4; in one year in ten it comes after May 18. Waiting until May 18 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wyoming climateThe statewide normals and every place in the state
- Basin, WY10 miles from this station, 48.9°F a year
- Shell, WY15 miles from this station, 44.8°F a year
- Emblem, WY16 miles from this station, 44.9°F a year
- Lovell, WY27 miles from this station, 44.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made