Callao, Utah climate: Climate normals at a NOAA weather station
Callao's normal year runs from 14°F January nights to 91°F July afternoons, with 6.6 inches of precipitation and 12 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.6°C, January lows of −10°C, July highs of 33°C, 168 mm of precipitation a year.
- NOAA stationCallao
- Station IDUSC00421144
- Location39.90°N 113.71°W
- Elevation4,342 ft (1,323 m)
On October 23, the normal high in Callao is 62°F and the normal low 30°F, and the chance of measurable rain or snow is 12%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Callao.
- Jan 38° 14°
- Feb 45° 20°
- Mar 56° 27°
- Apr 63° 34°
- May 72° 42°
- Jun 82° 50°
- Jul 91° 58°
- Aug 89° 55°
- Sep 79° 45°
- Oct 65° 32°
- Nov 50° 22°
- Dec 39° 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 at Callao each month?
July is the warmest month, with normal highs of 91°F; January the coldest, with normal lows of 14°F. The most precipitation falls in May (1.03 in), the least in July (0.37 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 38°F | 14°F | 26.1°F | 0.48 | 3.6 | 5 | <1 | 30 | 9 h 40 min |
| February | 45°F | 20°F | 32.8°F | 0.44 | 2.2 | 4 | <1 | 26 | 10 h 40 min |
| March | 56°F | 27°F | 41.6°F | 0.52 | 0.9 | 5 | <1 | 23 | 11 h 50 min |
| April | 63°F | 34°F | 48.4°F | 0.78 | 0.6 | 6 | <1 | 12 | 13 h 10 min |
| May | 72°F | 42°F | 56.9°F | 1.03 | 0.0 | 7 | 1 | 2 | 14 h 20 min |
| June | 82°F | 50°F | 66.0°F | 0.55 | 0.0 | 4 | 9 | <1 | 15 h |
| July | 91°F | 58°F | 74.1°F | 0.37 | 0.0 | 4 | 22 | <1 | 14 h 50 min |
| August | 89°F | 55°F | 72.2°F | 0.48 | 0.0 | 4 | 20 | <1 | 13 h 50 min |
| September | 79°F | 45°F | 62.0°F | 0.55 | 0.0 | 4 | 3 | 2 | 12 h 30 min |
| October | 65°F | 32°F | 48.7°F | 0.65 | 0.0 | 4 | <1 | 15 | 11 h 10 min |
| November | 50°F | 22°F | 36.3°F | 0.38 | 1.2 | 3 | <1 | 26 | 10 h |
| December | 39°F | 15°F | 26.9°F | 0.38 | 3.5 | 4 | <1 | 30 | 9 h 20 min |
| Year (annual) | 64°F | 34°F | 49.3°F | 6.61 | 12.0 | 53 | 54 | 165 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 3°C | −10°C | −3.3°C | 12 mm | 9 cm |
| February | 7°C | −6°C | 0.4°C | 11 mm | 6 cm |
| March | 13°C | −3°C | 5.3°C | 13 mm | 2 cm |
| April | 17°C | 1°C | 9.1°C | 20 mm | 2 cm |
| May | 22°C | 5°C | 13.8°C | 26 mm | 0 cm |
| June | 28°C | 10°C | 18.9°C | 14 mm | 0 cm |
| July | 33°C | 14°C | 23.4°C | 9 mm | 0 cm |
| August | 32°C | 13°C | 22.3°C | 12 mm | 0 cm |
| September | 26°C | 7°C | 16.7°C | 14 mm | 0 cm |
| October | 18°C | 0°C | 9.3°C | 17 mm | 0 cm |
| November | 10°C | −5°C | 2.4°C | 10 mm | 3 cm |
| December | 4°C | −10°C | −2.8°C | 10 mm | 9 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00421144; 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.
Which months are mildest at Callao?
Normal highs sit between 65°F and 85°F in May, June, September and October. Of those, June has the fewest days with rain (4).
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 USC00421144.
When is the last frost at Callao?
In Callao, the last spring frost (32°F) comes after May 14 in half of years and after June 4 in one year in ten; the first autumn frost comes before September 28 in half of years and before September 14 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 141 year in 10 after June 4; 9 in 10 after April 29
- First autumn frost, half of years before
- September 281 year in 10 before September 14; 9 in 10 before October 12
NOAA puts the median frost-free season at 135 days, and the season without a hard freeze (28°F) at 160 days.
A hard freeze (28°F) comes after April 30 in half of springs and before October 8 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Callao in zone 6b in ZIP code 84034, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 6b: the coldest night of a typical year reaches −4°F (26 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 USC00421144; 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 at Callao?
In a normal year in Callao, 54 days a year reach 90°F (2 of them 100°F or more), 165 nights fall to 32°F or colder and 53 days bring measurable precipitation.
- Days at 90°F or more
- 54a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 165a normal year
- Days that stay below freezing
- 18high of 32°F or less
- Days with 0.01 inch of precipitation
- 53a normal year
- Days with 1 inch of snow or more
- 4a normal year
The highest temperature in this station's record (since 1902) is 106°F, on August 2, 2000; the lowest is −24°F, on January 12, 1963.
The wettest calendar year on that record is 2019, with 10.86 in; the snowiest season is 1992–93, with 50.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00421144; records: ACIS (NOAA Regional Climate Centers), station USC00421144. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Callao?
Over a year 83% of the sunlight that would reach the ground under clear skies gets through the clouds at Callao, 5.0 kWh per square metre a day. September is the sunniest month (89%) and December the cloudiest (71%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 72% | 2.4 |
| February | 74% | 3.3 |
| March | 79% | 4.8 |
| April | 81% | 6.1 |
| May | 83% | 7.1 |
| June | 89% | 8.0 |
| July | 87% | 7.4 |
| August | 88% | 6.7 |
| September | 89% | 5.7 |
| October | 85% | 4.1 |
| November | 79% | 2.8 |
| December | 71% | 2.0 |
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 many heating and cooling degree days does Callao record?
A normal year at Callao brings 6,383 heating degree days, 19% more than the median U.S. place (5,373), and 697 cooling degree days, 23% 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 2,705 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,206 | 0 |
| February | 902 | 0 |
| March | 726 | 0 |
| April | 499 | 1 |
| May | 270 | 19 |
| June | 77 | 106 |
| July | 4 | 286 |
| August | 11 | 234 |
| September | 141 | 51 |
| October | 505 | 1 |
| November | 863 | 0 |
| December | 1,181 | 0 |
| Year (annual) | 6,383 | 697 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00421144. 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.
Have recent years at Callao been warmer than normal?
2025 averaged 52.9°F, 3.6°F above the 1991-2020 normal of 49.3°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 50.6°F | +1.3°F | 5.71 | 12.7 |
| 2022 | 49.5°F | +0.2°F | 6.12 | 17.5 |
| 2023 | 48.7°F | −0.6°F | 5.58 | 14.6 |
| 2024 | 51.9°F | +2.6°F | 4.32 | 10.3 |
| 2025 | 52.9°F | +3.6°F | 4.33 | 6.9 |
Over 47 complete years from 1965 to 2025, the station's annual mean temperature rose at a fitted 4.6°F per century (+0.26°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00421144; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Callao's climate compare?
Callao is warmer than 46 of the 97 places with their own NOAA record in Utah, and wetter than 4. Across the 7,247 U.S. stations with normals, its annual mean of 49.3°F is warmer than 37%.
In the Köppen classification computed from these normals, Callao 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.
Questions about Callao's climate
What is the coldest month at Callao?
January, with a normal high of 38°F and a normal low of 14°F. The warmest is July (91°F by day, 58°F at night).
Does it snow at Callao?
Yes: 12 inches in a normal year, falling on 8 days with 0.1 inch or more, the most in January (3.6 inches).
What is the rainiest month at Callao?
May, with 1.03 in of precipitation in a normal year; the driest is July with 0.37 in.
What plant hardiness zone is Callao in?
The USDA's 2023 map puts Callao in zone 6b in ZIP code 84034, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −4°F (26 years, 1991-2020): zone 6b.
How late can frost come at Callao?
In half of years the last 32°F night comes after May 14; in one year in ten it comes after June 4. Waiting until June 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Utah climateThe statewide normals and every place in the state
- Fish Springs National Wildlife Refuge, UT17 miles from this station, 53.1°F a year
- Ibapah, UT17 miles from this station, 48.3°F a year
- Partoun, UT21 miles from this station, 51.4°F a year
- Granite Peak Dugway Proving Ground, UT26 miles from this station, 54.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made