Copco #1 Dam, California climate: Climate normals at a NOAA weather station
Copco #1 Dam's normal year runs from 26°F December nights to 93°F July afternoons, with 20.4 inches of precipitation and 15 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.1°C, December lows of −3°C, July highs of 34°C, 519 mm of precipitation a year.
- NOAA stationCopco #1 Dam
- Station IDUSC00041990
- Location41.98°N 122.34°W
- Elevation2,703 ft (824 m)
On October 23, the normal high in Copco #1 Dam is 66°F and the normal low 37°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 Copco #1 Dam.
- Jan 48° 27°
- Feb 53° 29°
- Mar 58° 32°
- Apr 64° 35°
- May 74° 42°
- Jun 82° 49°
- Jul 93° 56°
- Aug 93° 55°
- Sep 85° 49°
- Oct 70° 39°
- Nov 56° 32°
- Dec 47° 26°
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 Copco #1 Dam each month?
July is the warmest month, with normal highs of 93°F; December the coldest, with normal lows of 26°F. The most precipitation falls in December (3.51 in), the least in August (0.25 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 48°F | 27°F | 37.3°F | 3.37 | 4.7 | 13 | <1 | 26 | 9 h 30 min |
| February | 53°F | 29°F | 41.1°F | 2.28 | 2.7 | 10 | <1 | 21 | 10 h 30 min |
| March | 58°F | 32°F | 45.3°F | 2.01 | 0.6 | 12 | <1 | 15 | 11 h 50 min |
| April | 64°F | 35°F | 49.5°F | 1.69 | 0.6 | 11 | <1 | 9 | 13 h 20 min |
| May | 74°F | 42°F | 57.8°F | 1.40 | 0.0 | 8 | 1 | 3 | 14 h 30 min |
| June | 82°F | 49°F | 65.3°F | 0.90 | 0.0 | 4 | 10 | 1 | 15 h 10 min |
| July | 93°F | 56°F | 74.3°F | 0.47 | 0.0 | 2 | 23 | <1 | 15 h |
| August | 93°F | 55°F | 74.1°F | 0.25 | 0.0 | 2 | 26 | <1 | 14 h |
| September | 85°F | 49°F | 66.9°F | 0.48 | 0.0 | 3 | 13 | <1 | 12 h 30 min |
| October | 70°F | 39°F | 54.4°F | 1.39 | 0.0 | 6 | 1 | 4 | 11 h 10 min |
| November | 56°F | 32°F | 43.7°F | 2.68 | 1.5 | 11 | <1 | 15 | 9 h 50 min |
| December | 47°F | 26°F | 36.4°F | 3.51 | 4.4 | 13 | <1 | 25 | 9 h 10 min |
| Year (annual) | 69°F | 39°F | 53.8°F | 20.43 | 14.5 | 94 | 73 | 119 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 9°C | −3°C | 2.9°C | 86 mm | 12 cm |
| February | 12°C | −2°C | 5.1°C | 58 mm | 7 cm |
| March | 15°C | 0°C | 7.4°C | 51 mm | 2 cm |
| April | 18°C | 2°C | 9.7°C | 43 mm | 2 cm |
| May | 23°C | 5°C | 14.3°C | 36 mm | 0 cm |
| June | 28°C | 9°C | 18.5°C | 23 mm | 0 cm |
| July | 34°C | 13°C | 23.5°C | 12 mm | 0 cm |
| August | 34°C | 13°C | 23.4°C | 6 mm | 0 cm |
| September | 30°C | 9°C | 19.4°C | 12 mm | 0 cm |
| October | 21°C | 4°C | 12.4°C | 35 mm | 0 cm |
| November | 13°C | 0°C | 6.5°C | 68 mm | 4 cm |
| December | 8°C | −3°C | 2.4°C | 89 mm | 11 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00041990; 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 Copco #1 Dam?
Normal highs sit between 65°F and 85°F in May, June 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 USC00041990.
When is the last frost at Copco #1 Dam?
In Copco #1 Dam, the last spring frost (32°F) comes after May 4 in half of years and after May 31 in one year in ten; the first autumn frost comes before October 21 in half of years and before October 10 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 41 year in 10 after May 31; 9 in 10 after April 15
- First autumn frost, half of years before
- October 211 year in 10 before October 10; 9 in 10 before November 4
NOAA puts the median frost-free season at 168 days, and the season without a hard freeze (28°F) at 198 days.
A hard freeze (28°F) comes after April 16 in half of springs and before November 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Copco #1 Dam in zone 7b in ZIP code 96064, the nearest ZIP area.
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00041990; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Copco #1 Dam?
In a normal year in Copco #1 Dam, 73 days a year reach 90°F (15 of them 100°F or more), 119 nights fall to 32°F or colder and 94 days bring measurable precipitation.
- Days at 90°F or more
- 73a normal year
- Days at 100°F or more
- 15a normal year
- Nights at 32°F or colder
- 119a normal year
- Days that stay below freezing
- 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 94a normal year
- Days with 1 inch of snow or more
- 6a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00041990.
How sunny is it at Copco #1 Dam?
Over a year 83% of the sunlight that would reach the ground under clear skies gets through the clouds at Copco #1 Dam, 4.8 kWh per square metre a day. July is the sunniest month (94%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 1.9 |
| February | 71% | 2.9 |
| March | 71% | 4.0 |
| April | 76% | 5.6 |
| May | 81% | 6.9 |
| June | 89% | 8.0 |
| July | 94% | 8.1 |
| August | 94% | 7.1 |
| September | 92% | 5.7 |
| October | 85% | 3.8 |
| November | 72% | 2.3 |
| December | 64% | 1.6 |
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 Copco #1 Dam record?
A normal year at Copco #1 Dam brings 4,895 heating degree days, 9% fewer than the median U.S. place (5,373), and 852 cooling degree days, 6% 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 3,047 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 859 | 0 |
| February | 671 | 0 |
| March | 611 | 0 |
| April | 464 | 1 |
| May | 245 | 23 |
| June | 102 | 109 |
| July | 7 | 295 |
| August | 2 | 284 |
| September | 72 | 129 |
| October | 341 | 11 |
| November | 637 | 0 |
| December | 884 | 0 |
| Year (annual) | 4,895 | 852 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00041990. 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.
How does Copco #1 Dam's climate compare?
Copco #1 Dam is warmer than 37 of the 219 places with their own NOAA record in California, and wetter than 138. Across the 7,247 U.S. stations with normals, its annual mean of 53.8°F is warmer than 56%.
In the Köppen classification computed from these normals, Copco #1 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 Copco #1 Dam's climate
What is the coldest month at Copco #1 Dam?
December, with a normal high of 47°F and a normal low of 26°F. The warmest is July (93°F by day, 56°F at night).
Does it snow at Copco #1 Dam?
Yes: 15 inches in a normal year, falling on 8 days with 0.1 inch or more, the most in January (4.7 inches).
What is the rainiest month at Copco #1 Dam?
December, with 3.51 in of precipitation in a normal year; the driest is August with 0.25 in.
What plant hardiness zone is Copco #1 Dam in?
The USDA's 2023 map puts Copco #1 Dam in zone 7b in ZIP code 96064, the nearest ZIP area.
How late can frost come at Copco #1 Dam?
In half of years the last 32°F night comes after May 4; in one year in ten it comes after May 31. Waiting until May 31 leaves about a one-in-ten chance of a later frost.
Nearby and next
- California climateThe statewide normals and every place in the state
- Montague, CA16 miles from this station, 52.8°F a year
- Howard Prairie Dam, OR17 miles from this station, 44.1°F a year
- Keno, OR24 miles from this station, 47.5°F a year
- Yreka, CA25 miles from this station, 53.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made