Henshaw Dam, California climate: Climate normals at a NOAA weather station
Henshaw Dam's normal year runs from 30°F December nights to 94°F August afternoons, with 25.2 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.2°C, December lows of −1°C, August highs of 34°C, 641 mm of precipitation a year.
- NOAA stationHenshaw Dam
- Station IDUSC00043914
- Location33.24°N 116.76°W
- Elevation2,700 ft (823 m)
On October 23, the normal high in Henshaw Dam is 77°F and the normal low 39°F, and the chance of measurable rain or snow is 11%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Henshaw Dam.
- Jan 61° 31°
- Feb 61° 32°
- Mar 65° 35°
- Apr 69° 38°
- May 75° 43°
- Jun 85° 46°
- Jul 92° 53°
- Aug 94° 54°
- Sep 89° 49°
- Oct 79° 40°
- Nov 69° 34°
- Dec 60° 30°
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 Henshaw Dam each month?
August is the warmest month, with normal highs of 94°F; December the coldest, with normal lows of 30°F. The most precipitation falls in February (5.88 in), the least in June (0.11 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 61°F | 31°F | 45.7°F | 5.26 | 8 | <1 | 22 | 10 h 10 min |
| February | 61°F | 32°F | 46.6°F | 5.88 | 9 | <1 | 17 | 11 h |
| March | 65°F | 35°F | 49.9°F | 4.09 | 7 | <1 | 13 | 12 h |
| April | 69°F | 38°F | 53.3°F | 1.73 | 5 | <1 | 7 | 13 h |
| May | 75°F | 43°F | 59.2°F | 0.70 | 3 | 3 | 2 | 13 h 50 min |
| June | 85°F | 46°F | 65.6°F | 0.11 | 1 | 12 | <1 | 14 h 20 min |
| July | 92°F | 53°F | 72.6°F | 0.18 | 1 | 23 | <1 | 14 h 10 min |
| August | 94°F | 54°F | 73.7°F | 0.29 | 1 | 25 | <1 | 13 h 30 min |
| September | 89°F | 49°F | 68.7°F | 0.44 | 2 | 19 | 1 | 12 h 30 min |
| October | 79°F | 40°F | 59.4°F | 0.93 | 3 | 6 | 5 | 11 h 20 min |
| November | 69°F | 34°F | 51.2°F | 1.87 | 4 | <1 | 15 | 10 h 30 min |
| December | 60°F | 30°F | 44.7°F | 3.75 | 7 | <1 | 23 | 10 h |
| Year (annual) | 75°F | 40°F | 57.5°F | 25.23 | 50 | 88 | 105 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 16°C | −1°C | 7.6°C | 134 mm |
| February | 16°C | 0°C | 8.1°C | 149 mm |
| March | 18°C | 2°C | 9.9°C | 104 mm |
| April | 21°C | 3°C | 11.8°C | 44 mm |
| May | 24°C | 6°C | 15.1°C | 18 mm |
| June | 29°C | 8°C | 18.7°C | 3 mm |
| July | 33°C | 12°C | 22.6°C | 5 mm |
| August | 34°C | 12°C | 23.2°C | 7 mm |
| September | 32°C | 9°C | 20.4°C | 11 mm |
| October | 26°C | 5°C | 15.2°C | 24 mm |
| November | 20°C | 1°C | 10.7°C | 47 mm |
| December | 15°C | −1°C | 7.1°C | 95 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Palomar Mountain Obsy (11 miles away), gets 26 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00043914; 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 Henshaw Dam?
Normal highs sit between 65°F and 85°F in April, May, June, October and November. Of those, June 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 USC00043914.
When is the last frost at Henshaw Dam?
In Henshaw Dam, the last spring frost (32°F) comes after April 18 in half of years and after May 14 in one year in ten; the first autumn frost comes before October 26 in half of years and before October 9 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
- April 181 year in 10 after May 14; 9 in 10 after March 30
- First autumn frost, half of years before
- October 261 year in 10 before October 9; 9 in 10 before November 13
NOAA puts the median frost-free season at 189 days, and the season without a hard freeze (28°F) at 239 days.
A hard freeze (28°F) comes after March 14 in half of springs and before November 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Henshaw Dam in zone 9a in ZIP code 92070, 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 8b: the coldest night of a typical year reaches 18°F (27 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 California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00043914; 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 Henshaw Dam?
In a normal year in Henshaw Dam, 88 days a year reach 90°F (14 of them 100°F or more), 105 nights fall to 32°F or colder and 50 days bring measurable precipitation.
- Days at 90°F or more
- 88a normal year
- Days at 100°F or more
- 14a normal year
- Nights at 32°F or colder
- 105a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 50a normal year
The highest temperature in this station's record (since 1942) is 120°F, on July 29, 1980; the lowest is 8°F, on January 14, 2007.
The wettest calendar year on that record is 1993, with 52.49 in; the snowiest season is 1948–49, with 21.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00043914; records: ACIS (NOAA Regional Climate Centers), station USC00043914. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Henshaw Dam?
Over a year 91% of the sunlight that would reach the ground under clear skies gets through the clouds at Henshaw Dam, 5.8 kWh per square metre a day. June is the sunniest month (96%) and February the cloudiest (84%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 85% | 3.4 |
| February | 84% | 4.3 |
| March | 88% | 5.7 |
| April | 90% | 7.0 |
| May | 93% | 7.9 |
| June | 96% | 8.4 |
| July | 93% | 7.8 |
| August | 94% | 7.3 |
| September | 94% | 6.3 |
| October | 92% | 5.0 |
| November | 89% | 3.7 |
| December | 85% | 3.0 |
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 Henshaw Dam record?
A normal year at Henshaw Dam brings 3,477 heating degree days, 35% fewer than the median U.S. place (5,373), and 780 cooling degree days, 14% fewer than the median (908). Six months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,418 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 598 | 0 |
| February | 514 | 0 |
| March | 468 | 0 |
| April | 352 | 1 |
| May | 198 | 18 |
| June | 64 | 81 |
| July | 6 | 244 |
| August | 5 | 274 |
| September | 34 | 145 |
| October | 192 | 18 |
| November | 414 | 0 |
| December | 631 | 0 |
| Year (annual) | 3,477 | 780 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00043914. 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 Henshaw Dam been warmer than normal?
2024 averaged 58.5°F, 1.0°F above the 1991-2020 normal of 57.5°F. 2 of the 2 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2022 | 58.9°F | +1.4°F | 14.41 |
| 2024 | 58.5°F | +1.0°F | 23.35 |
Over 51 complete years from 1943 to 2024, the station's annual mean temperature rose at a fitted 6.5°F per century (+0.36°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00043914; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Henshaw Dam's climate compare?
Henshaw Dam is warmer than 55 of the 219 places with their own NOAA record in California, and wetter than 158. Across the 7,247 U.S. stations with normals, its annual mean of 57.5°F is warmer than 68%.
In the Köppen classification computed from these normals, Henshaw Dam is Csa: temperate, dry-summer, hot 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 Henshaw Dam's climate
What is the coldest month at Henshaw Dam?
December, with a normal high of 60°F and a normal low of 30°F. The warmest is August (94°F by day, 54°F at night).
Does it snow at Henshaw Dam?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Palomar Mountain Obsy (11 miles away), records 26 inches of snow in a normal year.
What is the rainiest month at Henshaw Dam?
February, with 5.88 in of precipitation in a normal year; the driest is June with 0.11 in.
What plant hardiness zone is Henshaw Dam in?
The USDA's 2023 map puts Henshaw Dam in zone 9a in ZIP code 92070, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches 18°F (27 years, 1991-2020): zone 8b.
How late can frost come at Henshaw Dam?
In half of years the last 32°F night comes after April 18; in one year in ten it comes after May 14. Waiting until May 14 leaves about a one-in-ten chance of a later frost.
Nearby and next
- California climateThe statewide normals and every place in the state
- Palomar Mountain Obsy, CA11 miles from this station, 57.1°F a year
- Julian, CA15 miles from this station, 57.8°F a year
- Valley Center, CA16 miles from this station, 62.7°F a year
- Ramona, CA16 miles from this station, 61.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made