Sunnyvale, California climate: Normal weather by month, frost dates and records
Sunnyvale's normal year runs from 42°F December nights to 77°F August afternoons, with 13.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 15.5°C, December lows of 6°C, August highs of 25°C, 342 mm of precipitation a year.
- NOAA stationMoffett Federal Airfield
- Station IDUSW00023244
- Location37.41°N 122.05°W
- Elevation39 ft (12 m)
- From the center2 miles
- Population156,792
On October 14, the normal high in Sunnyvale is 75°F and the normal low 54°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 Sunnyvale.
- Jan 59° 42°
- Feb 62° 45°
- Mar 65° 47°
- Apr 68° 49°
- May 72° 53°
- Jun 76° 56°
- Jul 77° 59°
- Aug 77° 59°
- Sep 78° 57°
- Oct 74° 53°
- Nov 66° 46°
- Dec 59° 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 Sunnyvale each month?
August is the warmest month, with normal highs of 77°F; December the coldest, with normal lows of 42°F. The most precipitation falls in February (2.90 in), the least in July (0.00 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 59°F | 42°F | 50.7°F | 2.49 | 11 | <1 | 1 | 9 h 50 min |
| February | 62°F | 45°F | 53.1°F | 2.90 | 11 | <1 | <1 | 10 h 50 min |
| March | 65°F | 47°F | 55.8°F | 2.04 | 10 | <1 | <1 | 11 h 50 min |
| April | 68°F | 49°F | 58.4°F | 0.98 | 6 | <1 | <1 | 13 h 10 min |
| May | 72°F | 53°F | 62.1°F | 0.43 | 3 | 1 | <1 | 14 h 10 min |
| June | 76°F | 56°F | 65.8°F | 0.10 | 1 | 2 | <1 | 14 h 40 min |
| July | 77°F | 59°F | 67.7°F | 0.00 | <1 | 1 | <1 | 14 h 30 min |
| August | 77°F | 59°F | 68.0°F | 0.01 | <1 | 2 | <1 | 13 h 40 min |
| September | 78°F | 57°F | 67.5°F | 0.07 | 1 | 3 | <1 | 12 h 30 min |
| October | 74°F | 53°F | 63.6°F | 0.56 | 4 | 1 | <1 | 11 h 20 min |
| November | 66°F | 46°F | 55.9°F | 1.36 | 9 | <1 | <1 | 10 h 10 min |
| December | 59°F | 42°F | 50.5°F | 2.51 | 11 | <1 | 1 | 9 h 40 min |
| Year (annual) | 69°F | 51°F | 59.9°F | 13.45 | 66 | 9 | 2 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 15°C | 6°C | 10.4°C | 63 mm |
| February | 17°C | 7°C | 11.7°C | 74 mm |
| March | 18°C | 8°C | 13.2°C | 52 mm |
| April | 20°C | 9°C | 14.7°C | 25 mm |
| May | 22°C | 11°C | 16.7°C | 11 mm |
| June | 24°C | 13°C | 18.8°C | 3 mm |
| July | 25°C | 15°C | 19.8°C | 0 mm |
| August | 25°C | 15°C | 20.0°C | 0 mm |
| September | 25°C | 14°C | 19.7°C | 2 mm |
| October | 23°C | 12°C | 17.6°C | 14 mm |
| November | 19°C | 8°C | 13.3°C | 35 mm |
| December | 15°C | 6°C | 10.3°C | 64 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00023244; 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 Sunnyvale?
Normal highs sit between 65°F and 85°F in March, April, May, June, July, August, September, October and November. Of those, July has the fewest days with rain (0).
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 USW00023244.
When is the last frost in Sunnyvale?
In Sunnyvale, the last spring frost (32°F) comes after January 6 in half of years and after February 4 in one year in ten; the first autumn frost comes before December 23 in half of years and before December 3 in one year in ten. A night at 32°F or colder comes at all in 70% 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 61 year in 10 after February 4; 9 in 10 after December 16
- First autumn frost, half of years before
- December 231 year in 10 before December 3; 9 in 10 before January 16
NOAA puts the median frost-free season at 353 days, and the season without a hard freeze (28°F) at 365 days.
A hard freeze (28°F) comes after January 1 in half of springs and before December 31 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sunnyvale in zones 9b to 10a across its 4 ZIP code areas (9b in 94087, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Sunnyvale's NOAA station is in zone 10a: the coldest night of a typical year reaches 31°F (22 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 USW00023244; 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.
What hardiness zone is each Sunnyvale ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Sunnyvale's 4 ZIP code areas run from zone 9b to 10a: 2 in 10a and 2 in 9b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Sunnyvale?
In a normal year in Sunnyvale, 9 days a year reach 90°F (1 of them 100°F or more), 2 nights fall to 32°F or colder and 66 days bring measurable precipitation.
- Days at 90°F or more
- 9a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 2a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 66a normal year
The highest temperature in this station's record (since 1945) is 106°F, on June 14, 2000; the lowest is 21°F, on January 5, 1949.
The wettest calendar year on that record is 1983, with 31.40 in; the snowiest season is 1961–62, with 1.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00023244; records: ACIS (NOAA Regional Climate Centers), station USW00023244. Records use complete months only; a month missing more than three days is left out.
How sunny is Sunnyvale?
Over a year 80% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Sunnyvale, 4.7 kWh per square metre a day. June is the sunniest month (84%) and December the cloudiest (74%). Among the 459 U.S. places of 50,000 or more, that ranks tied 125th (with 50 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 76% | 2.5 |
| February | 77% | 3.4 |
| March | 79% | 4.6 |
| April | 82% | 6.0 |
| May | 81% | 6.7 |
| June | 84% | 7.3 |
| July | 78% | 6.5 |
| August | 77% | 5.8 |
| September | 82% | 5.1 |
| October | 83% | 4.0 |
| November | 81% | 2.8 |
| December | 74% | 2.1 |
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 Sunnyvale need?
A normal year in Sunnyvale brings 2,264 heating degree days, 58% fewer than the median U.S. place (5,373), and 427 cooling degree days, 53% fewer than the median (908). Three months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,761 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 443 | 0 |
| February | 332 | 0 |
| March | 285 | 1 |
| April | 205 | 9 |
| May | 116 | 26 |
| June | 39 | 63 |
| July | 11 | 95 |
| August | 8 | 99 |
| September | 18 | 93 |
| October | 83 | 40 |
| November | 275 | 2 |
| December | 449 | 0 |
| Year (annual) | 2,264 | 427 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00023244. 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 Sunnyvale been warmer than normal lately?
2025 averaged 60.2°F, 0.3°F above the 1991-2020 normal of 59.9°F.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2025 | 60.2°F | +0.3°F | – |
Over 59 complete years from 1946 to 2025, the station's annual mean temperature rose at a fitted 5.4°F per century (+0.30°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00023244; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Sunnyvale's climate compare?
Sunnyvale is warmer than 93 of the other 218 places with their own NOAA record in California, and wetter than 84. Across the 7,247 U.S. stations with normals, its annual mean of 59.9°F is warmer than 75%.
In the Köppen classification computed from these normals, Sunnyvale is Csb: temperate, 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.
Which places near Sunnyvale share this climate record?
4 places have no NOAA station with 1991-2020 normals of their 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.
- Mountain View, CAalso near: Palo Alto (5 mi, 58.5°F a year); Skyline Ridge Preserve (8 mi, 57.1°F a year)87,316 people · 2 mi W
- Cupertino, CAalso near: San Jose (7 mi, 60.7°F a year); Los Gatos (8 mi, 59.7°F a year)58,710 people · 6 mi S
- Los Altos, CA30,864 people · 4 mi SW
- Loyola, CA3,883 people · 5 mi SW
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 Sunnyvale's climate
What is the coldest month in Sunnyvale?
December, with a normal high of 59°F and a normal low of 42°F. The warmest is August (77°F by day, 59°F at night).
What is the rainiest month in Sunnyvale?
February, with 2.90 in of precipitation in a normal year; the driest is July with 0.00 in.
What plant hardiness zone is Sunnyvale in?
The USDA's 2023 map puts Sunnyvale in zones 9b to 10a across its 4 ZIP code areas (9b in 94087, the largest). By the same method at Sunnyvale's NOAA station, the coldest night of a typical year reaches 31°F (22 years, 1991-2020): zone 10a.
How late can frost come in Sunnyvale?
In half of years the last 32°F night comes after January 6; in one year in ten it comes after February 4. Waiting until February 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Sunnyvale in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Palo Alto, CA6 miles from this station, 58.5°F a year
- San Jose, CA7 miles from this station, 60.7°F a year
- Newark, CA7 miles from this station, 59.9°F a year
- Fremont, CA9 miles from this station, 59.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made