Alta, Wyoming climate: Normal weather by month, frost dates and records
Alta's normal year runs from 12°F December nights to 79°F July afternoons, with 25.0 inches of precipitation and 113 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 4.7°C, December lows of −11°C, July highs of 26°C, 634 mm of precipitation a year.
- NOAA stationAlta (1 mi NNW)
- Station IDUSC00480140
- Location43.77°N 111.03°W
- Elevation6,440 ft (1,963 m)
- Population (census place)656
On October 23, the normal high in Alta is 50°F and the normal low 28°F, and the chance of measurable rain or snow is 22%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Alta.
- Jan 29° 12°
- Feb 32° 14°
- Mar 40° 21°
- Apr 48° 27°
- May 60° 36°
- Jun 69° 42°
- Jul 79° 49°
- Aug 78° 47°
- Sep 69° 40°
- Oct 53° 30°
- Nov 39° 20°
- Dec 28° 12°
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 Alta each month?
July is the warmest month, with normal highs of 79°F; December the coldest, with normal lows of 12°F. The most precipitation falls in May (3.01 in), the least in July (1.38 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 29°F | 12°F | 20.4°F | 2.49 | 21.7 | 9 | <1 | 31 | 9 h 20 min |
| February | 32°F | 14°F | 22.7°F | 1.84 | 16.2 | 8 | <1 | 28 | 10 h 30 min |
| March | 40°F | 21°F | 30.4°F | 2.10 | 15.3 | 9 | <1 | 28 | 11 h 50 min |
| April | 48°F | 27°F | 37.7°F | 2.49 | 13.5 | 9 | <1 | 23 | 13 h 20 min |
| May | 60°F | 36°F | 47.8°F | 3.01 | 2.5 | 10 | <1 | 11 | 14 h 40 min |
| June | 69°F | 42°F | 55.7°F | 2.31 | 0.3 | 8 | <1 | 3 | 15 h 30 min |
| July | 79°F | 49°F | 63.7°F | 1.38 | 0.0 | 5 | 1 | <1 | 15 h 10 min |
| August | 78°F | 47°F | 62.7°F | 1.38 | 0.0 | 6 | <1 | <1 | 14 h |
| September | 69°F | 40°F | 54.1°F | 1.85 | 0.5 | 6 | <1 | 5 | 12 h 30 min |
| October | 53°F | 30°F | 41.8°F | 2.06 | 5.9 | 7 | <1 | 19 | 11 h 10 min |
| November | 39°F | 20°F | 29.2°F | 1.93 | 15.8 | 8 | <1 | 27 | 9 h 40 min |
| December | 28°F | 12°F | 20.0°F | 2.14 | 21.7 | 9 | <1 | 30 | 9 h |
| Year (annual) | 52°F | 29°F | 40.5°F | 24.98 | 113.4 | 94 | 1 | 204 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −11°C | −6.4°C | 63 mm | 55 cm |
| February | 0°C | −10°C | −5.2°C | 47 mm | 41 cm |
| March | 4°C | −6°C | −0.9°C | 53 mm | 39 cm |
| April | 9°C | −3°C | 3.2°C | 63 mm | 34 cm |
| May | 16°C | 2°C | 8.8°C | 76 mm | 6 cm |
| June | 21°C | 6°C | 13.2°C | 59 mm | 1 cm |
| July | 26°C | 9°C | 17.6°C | 35 mm | 0 cm |
| August | 26°C | 8°C | 17.1°C | 35 mm | 0 cm |
| September | 20°C | 4°C | 12.3°C | 47 mm | 1 cm |
| October | 12°C | −1°C | 5.4°C | 52 mm | 15 cm |
| November | 4°C | −7°C | −1.6°C | 49 mm | 40 cm |
| December | −2°C | −11°C | −6.7°C | 54 mm | 55 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00480140; 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 Alta?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, July 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 USC00480140.
When is the last frost in Alta?
In Alta, the last spring frost (32°F) comes after June 14 in half of years and after July 4 in one year in ten; the first autumn frost comes before September 11 in half of years and before August 28 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
- June 141 year in 10 after July 4; 9 in 10 after May 23
- First autumn frost, half of years before
- September 111 year in 10 before August 28; 9 in 10 before September 26
NOAA puts the median frost-free season at 85 days, and the season without a hard freeze (28°F) at 120 days.
A hard freeze (28°F) comes after May 24 in half of springs and before September 23 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Alta in zone 5a in ZIP code 83414, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Alta's NOAA station is in zone 5b: the coldest night of a typical year reaches −15°F (29 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Wyoming · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00480140; 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 Alta?
In a normal year in Alta, 1 day a year reaches 90°F, 204 nights fall to 32°F or colder and 94 days bring measurable precipitation.
- Days at 90°F or more
- 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 204a normal year
- Days that stay below freezing
- 72high of 32°F or less
- Days with 0.01 inch of precipitation
- 94a normal year
- Days with 1 inch of snow or more
- 38a normal year
The highest temperature in this station's record (since 1909) is 98°F, on July 12, 2026; the lowest is −46°F, on February 9, 1933.
The wettest calendar year on that record is 1983, with 33.62 in; the snowiest season is 2010–11, with 187.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00480140; records: ACIS (NOAA Regional Climate Centers), station USC00480140. Records use complete months only; a month missing more than three days is left out.
How sunny is Alta?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Alta, 4.4 kWh per square metre a day. July is the sunniest month (89%) and December the cloudiest (58%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 64% | 1.8 |
| February | 66% | 2.7 |
| March | 69% | 4.0 |
| April | 70% | 5.2 |
| May | 74% | 6.3 |
| June | 82% | 7.3 |
| July | 89% | 7.6 |
| August | 87% | 6.5 |
| September | 83% | 5.0 |
| October | 74% | 3.2 |
| November | 66% | 1.9 |
| December | 58% | 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 Alta need?
A normal year in Alta brings 8,992 heating degree days, 67% more than the median U.S. place (5,373), and 91 cooling degree days, 90% fewer than the median (908). Nine months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,309 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,383 | 0 |
| February | 1,183 | 0 |
| March | 1,073 | 0 |
| April | 819 | 0 |
| May | 534 | 1 |
| June | 287 | 8 |
| July | 89 | 47 |
| August | 105 | 33 |
| September | 330 | 3 |
| October | 721 | 0 |
| November | 1,076 | 0 |
| December | 1,395 | 0 |
| Year (annual) | 8,992 | 91 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00480140. 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 Alta been warmer than normal lately?
2025 averaged 41.9°F, 1.4°F above the 1991-2020 normal of 40.5°F. 3 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 41.8°F | +1.3°F | 22.79 | 93.3 |
| 2022 | 39.1°F | −1.4°F | 16.29 | 79.0 |
| 2023 | 39.6°F | −0.9°F | 25.96 | 103.0 |
| 2024 | 41.2°F | +0.7°F | 19.51 | 126.4 |
| 2025 | 41.9°F | +1.4°F | 18.57 | 58.5 |
Over 77 complete years from 1910 to 2025, the station's annual mean temperature rose at a fitted 2.3°F per century (+0.13°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00480140; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Alta's climate compare?
Alta is warmer than 14 of the other 70 places with their own NOAA record in Wyoming, and wetter than 60. Across the 7,247 U.S. stations with normals, its annual mean of 40.5°F is warmer than 6%.
In the Köppen classification computed from these normals, Alta is Dfb: continental, no dry season, warm summer. 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 Alta share this climate record?
Victor has no NOAA station with 1991-2020 normals of its 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.
- Victor, ID2,442 people · 12 mi S
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 Alta's climate
What is the coldest month in Alta?
December, with a normal high of 28°F and a normal low of 12°F. The warmest is July (79°F by day, 49°F at night).
Does it snow in Alta?
Yes: 113 inches in a normal year, falling on 38 days with 0.1 inch or more, the most in January (21.7 inches).
What is the rainiest month in Alta?
May, with 3.01 in of precipitation in a normal year; the driest is July with 1.38 in.
What plant hardiness zone is Alta in?
The USDA's 2023 map puts Alta in zone 5a in ZIP code 83414, the nearest ZIP area. By the same method at Alta's NOAA station, the coldest night of a typical year reaches −15°F (29 years, 1991-2020): zone 5b.
How late can frost come in Alta?
In half of years the last 32°F night comes after June 14; in one year in ten it comes after July 4. Waiting until July 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wyoming climateThe statewide normals and every place in the state
- Driggs, ID5 miles from this station, 42.2°F a year
- Tetonia, ID14 miles from this station, 39.4°F a year
- Moose, WY18 miles from this station, 38.4°F a year
- Moran (5 mi WNW), WY23 miles from this station, 35.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made