Imperial, California climate: Normal weather by month, frost dates and records
Imperial's normal year runs from 42°F December nights to 105°F August afternoons, with 2.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 22.8°C, December lows of 6°C, August highs of 40°C, 70 mm of precipitation a year.
- NOAA stationImperial
- Station IDUSC00044223
- Location32.85°N 115.57°W
- Elevation-64 ft (-19 m)
- Population22,102
On October 23, the normal high in Imperial is 86°F and the normal low 59°F, and the chance of measurable rain or snow is 3%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Imperial.
- Jan 69° 43°
- Feb 72° 47°
- Mar 78° 52°
- Apr 84° 56°
- May 93° 63°
- Jun 101° 70°
- Jul 104° 77°
- Aug 105° 78°
- Sep 100° 73°
- Oct 89° 61°
- Nov 77° 50°
- Dec 68° 42°
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 Imperial each month?
August is the warmest month, with normal highs of 105°F; December the coldest, with normal lows of 42°F. The most precipitation falls in January (0.47 in), the least in June (0.00 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 69°F | 43°F | 56.0°F | 0.47 | 3 | <1 | 1 | 10 h 10 min |
| February | 72°F | 47°F | 59.4°F | 0.43 | 3 | <1 | <1 | 11 h |
| March | 78°F | 52°F | 65.0°F | 0.31 | 2 | 4 | <1 | 12 h |
| April | 84°F | 56°F | 70.4°F | 0.09 | 1 | 11 | <1 | 13 h |
| May | 93°F | 63°F | 77.8°F | 0.06 | <1 | 23 | <1 | 13 h 50 min |
| June | 101°F | 70°F | 85.4°F | 0.00 | <1 | 29 | <1 | 14 h 20 min |
| July | 104°F | 77°F | 90.9°F | 0.14 | 1 | 31 | <1 | 14 h 10 min |
| August | 105°F | 78°F | 91.4°F | 0.18 | 1 | 31 | <1 | 13 h 20 min |
| September | 100°F | 73°F | 86.6°F | 0.26 | 1 | 29 | <1 | 12 h 30 min |
| October | 89°F | 61°F | 75.2°F | 0.21 | 1 | 19 | <1 | 11 h 30 min |
| November | 77°F | 50°F | 63.2°F | 0.22 | 1 | 2 | <1 | 10 h 30 min |
| December | 68°F | 42°F | 54.9°F | 0.39 | 3 | <1 | 2 | 10 h |
| Year (annual) | 87°F | 59°F | 73.0°F | 2.76 | 17 | 179 | 4 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 20°C | 6°C | 13.3°C | 12 mm |
| February | 22°C | 8°C | 15.2°C | 11 mm |
| March | 26°C | 11°C | 18.3°C | 8 mm |
| April | 29°C | 14°C | 21.3°C | 2 mm |
| May | 34°C | 17°C | 25.4°C | 2 mm |
| June | 38°C | 21°C | 29.7°C | 0 mm |
| July | 40°C | 25°C | 32.7°C | 4 mm |
| August | 40°C | 26°C | 33.0°C | 5 mm |
| September | 38°C | 23°C | 30.3°C | 7 mm |
| October | 32°C | 16°C | 24.0°C | 5 mm |
| November | 25°C | 10°C | 17.3°C | 6 mm |
| December | 20°C | 6°C | 12.7°C | 10 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00044223; 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 Imperial?
Normal highs sit between 65°F and 85°F in January, February, March, April, November and December. Of those, April has the fewest days with rain (1).
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 USC00044223.
When is the last frost in Imperial?
In Imperial, the last spring frost (32°F) comes after January 4 in half of years and after February 7 in one year in ten; the first autumn frost comes before December 26 in half of years and before December 6 in one year in ten. A night at 32°F or colder comes at all in 61% of years here (NOAA).
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- January 41 year in 10 after February 7; 9 in 10 after December 13
- First autumn frost, half of years before
- December 261 year in 10 before December 6; 9 in 10 before January 25
NOAA puts the median frost-free season at 360 days, and the season without a hard freeze (28°F) at 365 days.
A hard freeze (28°F) comes after January 4 in half of springs and before January 1 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Imperial in zone 10a in ZIP code 92243, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Imperial's NOAA station is in zone 10a: the coldest night of a typical year reaches 31°F (29 complete years).
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00044223; 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 Imperial?
In a normal year in Imperial, 179 days a year reach 90°F (115 of them 100°F or more), 4 nights fall to 32°F or colder and 17 days bring measurable precipitation.
- Days at 90°F or more
- 179a normal year
- Days at 100°F or more
- 115a normal year
- Nights at 32°F or colder
- 4a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 17a normal year
The highest temperature in this station's record (since 1901) is 124°F, on July 6, 1905; the lowest is 16°F, on January 22, 1937.
The wettest calendar year on that record is 1906, with 7.08 in.
Source: NOAA NCEI 1991-2020 annual normals, station USC00044223; records: ACIS (NOAA Regional Climate Centers), station USC00044223. Records use complete months only; a month missing more than three days is left out.
How sunny is Imperial?
Over a year 93% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Imperial, 5.9 kWh per square metre a day. June is the sunniest month (97%) and December the cloudiest (87%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 89% | 3.6 |
| February | 89% | 4.5 |
| March | 92% | 6.0 |
| April | 94% | 7.3 |
| May | 96% | 8.1 |
| June | 97% | 8.4 |
| July | 93% | 7.7 |
| August | 94% | 7.2 |
| September | 95% | 6.3 |
| October | 94% | 5.1 |
| November | 91% | 3.9 |
| December | 87% | 3.2 |
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 Imperial need?
A normal year in Imperial brings 974 heating degree days, 82% fewer than the median U.S. place (5,373), and 3,921 cooling degree days, 4.3 times the median (908). One month needs 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 8,448 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 281 | 2 |
| February | 168 | 11 |
| March | 76 | 74 |
| April | 20 | 180 |
| May | 2 | 397 |
| June | 0 | 612 |
| July | 0 | 801 |
| August | 0 | 820 |
| September | 0 | 646 |
| October | 7 | 321 |
| November | 109 | 56 |
| December | 314 | 1 |
| Year (annual) | 974 | 3,921 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00044223. 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 Imperial been warmer than normal lately?
2025 averaged 76.4°F, 3.4°F above the 1991-2020 normal of 73.0°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 77.2°F | +4.2°F | 2.01 |
| 2022 | 76.6°F | +3.6°F | 2.25 |
| 2023 | 74.9°F | +1.9°F | 2.76 |
| 2024 | 76.8°F | +3.8°F | 2.23 |
| 2025 | 76.4°F | +3.4°F | 2.96 |
Over 79 complete years from 1905 to 2025, the station's annual mean temperature rose at a fitted 3.0°F per century (+0.17°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00044223; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Imperial's climate compare?
Imperial is warmer than 211 of the other 218 places with their own NOAA record in California, and wetter than 2. Across the 7,247 U.S. stations with normals, its annual mean of 73.0°F is warmer than 97%.
In the Köppen classification computed from these normals, Imperial is BWh: hot 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.
Which places near Imperial share this climate record?
Holtville 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.
- Holtville, CA5,612 people · 11 mi E
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 Imperial's climate
What is the coldest month in Imperial?
December, with a normal high of 68°F and a normal low of 42°F. The warmest is August (105°F by day, 78°F at night).
Does it snow in Imperial?
Rarely: NOAA's normal is no measurable snow a year.
What is the rainiest month in Imperial?
January, with 0.47 in of precipitation in a normal year; the driest is June with 0.00 in.
What plant hardiness zone is Imperial in?
The USDA's 2023 map puts Imperial in zone 10a in ZIP code 92243, the nearest ZIP area. By the same method at Imperial's NOAA station, the coldest night of a typical year reaches 31°F (29 years, 1991-2020): zone 10a.
How late can frost come in Imperial?
In half of years the last 32°F night comes after January 4; in one year in ten it comes after February 7. Waiting until February 7 leaves about a one-in-ten chance of a later frost.
Nearby and next
- California climateThe statewide normals and every place in the state
- El Centro, CA1 miles from this station, 73.7°F a year
- Brawley, CA7 miles from this station, 73.8°F a year
- Ocotillo Wells (2 mi W), CA41 miles from this station, 76.6°F a year
- Mount Laguna, CA50 miles from this station, 54.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made