Alta, Utah climate: Normal weather by month, frost dates and records
Alta's normal year runs from 15°F December nights to 73°F July afternoons, with 47.1 inches of precipitation and 458 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 3.9°C, December lows of −10°C, July highs of 23°C, 1,196 mm of precipitation a year.
- NOAA stationAlta
- Station IDUSC00420072
- Location40.59°N 111.64°W
- Elevation8,710 ft (2,655 m)
- Population228
On October 23, the normal high in Alta is 47°F and the normal low 29°F, and the chance of measurable rain or snow is 32%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Alta.
- Jan 31° 15°
- Feb 31° 15°
- Mar 37° 20°
- Apr 42° 25°
- May 53° 33°
- Jun 64° 42°
- Jul 73° 50°
- Aug 71° 49°
- Sep 62° 41°
- Oct 50° 31°
- Nov 37° 21°
- Dec 30° 15°
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 73°F; December the coldest, with normal lows of 15°F. The most precipitation falls in January (6.37 in), the least in July (1.48 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 31°F | 15°F | 22.9°F | 6.37 | 74.7 | 14 | <1 | 31 | 9 h 30 min |
| February | 31°F | 15°F | 23.0°F | 5.40 | 81.2 | 14 | <1 | 28 | 10 h 40 min |
| March | 37°F | 20°F | 28.5°F | 6.17 | 71.4 | 13 | <1 | 29 | 11 h 50 min |
| April | 42°F | 25°F | 33.6°F | 4.78 | 50.0 | 12 | <1 | 25 | 13 h 10 min |
| May | 53°F | 33°F | 43.0°F | 3.47 | 15.9 | 11 | <1 | 14 | 14 h 20 min |
| June | 64°F | 42°F | 53.3°F | 1.96 | 4.4 | 6 | <1 | 4 | 15 h |
| July | 73°F | 50°F | 61.6°F | 1.48 | 0.0 | 7 | <1 | <1 | 14 h 50 min |
| August | 71°F | 49°F | 60.2°F | 2.07 | 0.0 | 9 | <1 | <1 | 13 h 50 min |
| September | 62°F | 41°F | 51.7°F | 2.58 | 2.6 | 9 | <1 | 4 | 12 h 30 min |
| October | 50°F | 31°F | 40.3°F | 3.50 | 24.4 | 10 | <1 | 17 | 11 h 10 min |
| November | 37°F | 21°F | 29.1°F | 4.17 | 53.9 | 11 | <1 | 27 | 10 h |
| December | 30°F | 15°F | 22.3°F | 5.13 | 79.8 | 15 | <1 | 31 | 9 h 20 min |
| Year (annual) | 48°F | 30°F | 39.1°F | 47.08 | 458.3 | 129 | <1 | 209 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −9°C | −5.1°C | 162 mm | 190 cm |
| February | −1°C | −9°C | −5.0°C | 137 mm | 206 cm |
| March | 3°C | −7°C | −1.9°C | 157 mm | 181 cm |
| April | 6°C | −4°C | 0.9°C | 121 mm | 127 cm |
| May | 11°C | 1°C | 6.1°C | 88 mm | 40 cm |
| June | 18°C | 6°C | 11.8°C | 50 mm | 11 cm |
| July | 23°C | 10°C | 16.4°C | 38 mm | 0 cm |
| August | 22°C | 10°C | 15.7°C | 53 mm | 0 cm |
| September | 17°C | 5°C | 10.9°C | 66 mm | 7 cm |
| October | 10°C | −1°C | 4.6°C | 89 mm | 62 cm |
| November | 3°C | −6°C | −1.6°C | 106 mm | 137 cm |
| December | −1°C | −10°C | −5.4°C | 130 mm | 203 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00420072; 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 July and August. Of those, July has the fewest days with rain (7).
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 USC00420072.
When is the last frost in Alta?
In Alta, the last spring frost (32°F) comes after June 11 in half of years and after June 27 in one year in ten; the first autumn frost comes before September 18 in half of years and before September 3 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 111 year in 10 after June 27; 9 in 10 after May 26
- First autumn frost, half of years before
- September 181 year in 10 before September 3; 9 in 10 before September 29
NOAA puts the median frost-free season at 98 days, and the season without a hard freeze (28°F) at 117 days.
A hard freeze (28°F) comes after June 1 in half of springs and before September 27 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Alta in zone 6a in ZIP code 84121, 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 6a: the coldest night of a typical year reaches −7°F (24 complete years).
Frost dates for every NOAA station in Utah · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00420072; 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, a 90°F day is rare, 209 nights fall to 32°F or colder and 129 days bring measurable precipitation.
- Days at 90°F or more
- fewer than 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 209a normal year
- Days that stay below freezing
- 81high of 32°F or less
- Days with 0.01 inch of precipitation
- 129a normal year
- Days with 1 inch of snow or more
- 79a normal year
The highest temperature in this station's record (since 1906) is 94°F, on July 27, 1945; the lowest is −35°F, on January 1, 1979.
The wettest calendar year on that record is 1983, with 108.54 in; the snowiest season is 1982–83, with 849.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00420072; records: ACIS (NOAA Regional Climate Centers), station USC00420072. Records use complete months only; a month missing more than three days is left out.
How sunny is Alta?
Over a year 80% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Alta, 4.8 kWh per square metre a day. July is the sunniest month (88%) and December the cloudiest (67%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 71% | 2.3 |
| February | 72% | 3.2 |
| March | 75% | 4.5 |
| April | 74% | 5.6 |
| May | 77% | 6.6 |
| June | 86% | 7.8 |
| July | 88% | 7.5 |
| August | 86% | 6.6 |
| September | 85% | 5.4 |
| October | 80% | 3.8 |
| November | 72% | 2.5 |
| December | 67% | 1.9 |
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 9,440 heating degree days, 76% more than the median U.S. place (5,373), and 28 cooling degree days, 97% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,000 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,307 | 0 |
| February | 1,175 | 0 |
| March | 1,132 | 0 |
| April | 944 | 0 |
| May | 682 | 0 |
| June | 352 | 1 |
| July | 123 | 17 |
| August | 158 | 9 |
| September | 401 | 0 |
| October | 767 | 0 |
| November | 1,079 | 0 |
| December | 1,322 | 0 |
| Year (annual) | 9,440 | 28 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00420072. 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 41.6°F, 2.5°F above the 1991-2020 normal of 39.1°F. 3 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 39.6°F | +0.5°F | 53.34 | 441.0 |
| 2024 | 40.2°F | +1.1°F | 63.45 | 569.2 |
| 2025 | 41.6°F | +2.5°F | 49.22 | 416.4 |
Over 34 complete years from 1971 to 2025, the station's annual mean temperature rose at a fitted 6.3°F per century (+0.35°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00420072; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Alta's climate compare?
Alta is warmer than 2 of the other 96 places with their own NOAA record in Utah, and wetter than 90. Across the 7,247 U.S. stations with normals, its annual mean of 39.1°F is warmer than 4%.
In the Köppen classification computed from these normals, Alta is Dsb: continental, dry-summer, 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.
Questions about Alta's climate
What is the coldest month in Alta?
December, with a normal high of 30°F and a normal low of 15°F. The warmest is July (73°F by day, 50°F at night).
Does it snow in Alta?
Yes: 458 inches in a normal year, falling on 85 days with 0.1 inch or more, the most in February (81.2 inches).
What is the rainiest month in Alta?
January, with 6.37 in of precipitation in a normal year; the driest is July with 1.48 in.
What plant hardiness zone is Alta in?
The USDA's 2023 map puts Alta in zone 6a in ZIP code 84121, the nearest ZIP area. By the same method at Alta's NOAA station, the coldest night of a typical year reaches −7°F (24 years, 1991-2020): zone 6a.
How late can frost come in Alta?
In half of years the last 32°F night comes after June 11; in one year in ten it comes after June 27. Waiting until June 27 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Utah climateThe statewide normals and every place in the state
- Silver Lake Brighton, UT3 miles from this station, 37.4°F a year
- Snake Creek Powerhouse, UT7 miles from this station, 44.9°F a year
- Cottonwood Heights, UT8 miles from this station, 53.2°F a year
- Park City, UT8 miles from this station, 43.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made