Vacaville, California climate: Normal weather by month, frost dates and records
Vacaville's normal year runs from 37°F December nights to 95°F July afternoons, with 24.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 16.7°C, December lows of 3°C, July highs of 35°C, 631 mm of precipitation a year.
- NOAA stationVacaville Nut Tree Airport
- Station IDUSW00093241
- Location38.38°N 121.96°W
- Elevation109 ft (33 m)
- Population103,994
On October 23, the normal high in Vacaville is 77°F and the normal low 47°F, and the chance of measurable rain or snow is 14%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Vacaville.
- Jan 58° 38°
- Feb 63° 40°
- Mar 68° 43°
- Apr 73° 46°
- May 81° 51°
- Jun 90° 56°
- Jul 95° 59°
- Aug 94° 58°
- Sep 91° 56°
- Oct 80° 49°
- Nov 67° 42°
- Dec 58° 37°
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 Vacaville each month?
July is the warmest month, with normal highs of 95°F; December the coldest, with normal lows of 37°F. The most precipitation falls in January (5.26 in), the least in July (0.01 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 | 58°F | 38°F | 47.7°F | 5.26 | 11 | <1 | 7 | 9 h 50 min |
| February | 63°F | 40°F | 51.5°F | 5.06 | 9 | <1 | 3 | 10 h 40 min |
| March | 68°F | 43°F | 55.3°F | 3.69 | 9 | <1 | 1 | 11 h 50 min |
| April | 73°F | 46°F | 59.3°F | 1.29 | 5 | 1 | <1 | 13 h 10 min |
| May | 81°F | 51°F | 66.1°F | 0.81 | 3 | 5 | <1 | 14 h 10 min |
| June | 90°F | 56°F | 73.0°F | 0.17 | 1 | 15 | <1 | 14 h 50 min |
| July | 95°F | 59°F | 77.0°F | 0.01 | <1 | 24 | <1 | 14 h 40 min |
| August | 94°F | 58°F | 75.9°F | 0.02 | <1 | 23 | <1 | 13 h 40 min |
| September | 91°F | 56°F | 73.1°F | 0.06 | 1 | 16 | <1 | 12 h 30 min |
| October | 80°F | 49°F | 64.5°F | 1.08 | 3 | 4 | <1 | 11 h 20 min |
| November | 67°F | 42°F | 54.0°F | 2.31 | 8 | <1 | 2 | 10 h 10 min |
| December | 58°F | 37°F | 47.5°F | 5.08 | 10 | <1 | 8 | 9 h 30 min |
| Year (annual) | 76°F | 48°F | 62.1°F | 24.84 | 61 | 88 | 21 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 14°C | 3°C | 8.7°C | 134 mm |
| February | 17°C | 5°C | 10.8°C | 129 mm |
| March | 20°C | 6°C | 12.9°C | 94 mm |
| April | 23°C | 8°C | 15.2°C | 33 mm |
| May | 27°C | 11°C | 18.9°C | 21 mm |
| June | 32°C | 14°C | 22.8°C | 4 mm |
| July | 35°C | 15°C | 25.0°C | 0 mm |
| August | 34°C | 14°C | 24.4°C | 1 mm |
| September | 33°C | 13°C | 22.8°C | 2 mm |
| October | 27°C | 10°C | 18.1°C | 27 mm |
| November | 19°C | 5°C | 12.2°C | 59 mm |
| December | 14°C | 3°C | 8.6°C | 129 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Vacaville's own co-op station Vacaville station does: 0 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00093241; 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 Vacaville?
Normal highs sit between 65°F and 85°F in March, April, May, October and November. Of those, May has the fewest days with rain (3).
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 USW00093241.
When is the last frost in Vacaville?
In Vacaville, the last spring frost (32°F) comes after February 18 in half of years and after March 25 in one year in ten; the first autumn frost comes before November 28 in half of years and before November 12 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
- February 181 year in 10 after March 25; 9 in 10 after January 11
- First autumn frost, half of years before
- November 281 year in 10 before November 12; 9 in 10 before December 18
NOAA puts the median frost-free season at 283 days, and the season without a hard freeze (28°F) at 334 days.
A hard freeze (28°F) comes after January 15 in half of springs and before December 10 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Vacaville in zone 9b across its 2 ZIP code areas (9b in 95687, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Vacaville's NOAA station is in zone 9b: the coldest night of a typical year reaches 25°F (22 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 USW00093241; 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 Vacaville ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Vacaville's 2 ZIP code areas are all in zone 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 Vacaville?
In a normal year in Vacaville, 88 days a year reach 90°F (22 of them 100°F or more), 21 nights fall to 32°F or colder and 61 days bring measurable precipitation.
- Days at 90°F or more
- 88a normal year
- Days at 100°F or more
- 22a normal year
- Nights at 32°F or colder
- 21a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 61a normal year
The highest temperature in this station's record (since 1998) is 115°F, on July 10, 2021; the lowest is 17°F, on December 23, 1998.
The wettest calendar year on that record is 2017, with 39.62 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00093241; records: ACIS (NOAA Regional Climate Centers), station USW00093241. Records use complete months only; a month missing more than three days is left out.
How sunny is Vacaville?
Over a year 89% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Vacaville, 5.2 kWh per square metre a day. July is the sunniest month (98%) and January the cloudiest (70%). Among the 459 U.S. places of 50,000 or more, that ranks tied 39th (with 12 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 70% | 2.2 |
| February | 77% | 3.3 |
| March | 80% | 4.6 |
| April | 85% | 6.2 |
| May | 91% | 7.5 |
| June | 95% | 8.3 |
| July | 98% | 8.2 |
| August | 98% | 7.4 |
| September | 96% | 6.0 |
| October | 91% | 4.3 |
| November | 81% | 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 much heating and cooling does Vacaville need?
A normal year in Vacaville brings 2,446 heating degree days, 54% fewer than the median U.S. place (5,373), and 1,391 cooling degree days, 53% more than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 4,707 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 538 | 0 |
| February | 380 | 0 |
| March | 301 | 2 |
| April | 189 | 18 |
| May | 66 | 98 |
| June | 8 | 247 |
| July | 0 | 372 |
| August | 0 | 337 |
| September | 6 | 248 |
| October | 83 | 68 |
| November | 332 | 2 |
| December | 544 | 0 |
| Year (annual) | 2,446 | 1,391 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00093241. 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 Vacaville been warmer than normal lately?
2025 averaged 62.3°F, 0.2°F above the 1991-2020 normal of 62.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 63.0°F | +0.9°F | – |
| 2022 | 63.5°F | +1.4°F | 12.57 |
| 2023 | 61.6°F | −0.5°F | 31.03 |
| 2024 | 63.5°F | +1.4°F | 26.56 |
| 2025 | 62.3°F | +0.2°F | 21.18 |
Source: observed years: ACIS, station USW00093241. A year counts only with all twelve months complete.
How does Vacaville's climate compare?
Vacaville is warmer than 123 of the other 218 places with their own NOAA record in California, and wetter than 156. Across the 7,247 U.S. stations with normals, its annual mean of 62.1°F is warmer than 80%.
In the Köppen classification computed from these normals, Vacaville 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.
Which places near Vacaville share this climate record?
2 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.
- Hartley, CA1,966 people · 3 mi N
- Elmira, CA248 people · 3 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Vacaville's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Vacaville. This page uses Vacaville Nut Tree Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Vacaville station USC00049200 | 1 mi N | 110 ft | 63.6°F | 40°F | 97°F | 25.6 | 0 | January 31 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Vacaville's climate
What is the coldest month in Vacaville?
December, with a normal high of 58°F and a normal low of 37°F. The warmest is July (95°F by day, 59°F at night).
Does it snow in Vacaville?
Rarely. NOAA publishes no 1991-2020 snowfall normal for Vacaville's NOAA station; Vacaville's own co-op station Vacaville station records 0 inches of snow in a normal year.
What is the rainiest month in Vacaville?
January, with 5.26 in of precipitation in a normal year; the driest is July with 0.01 in.
What plant hardiness zone is Vacaville in?
The USDA's 2023 map puts Vacaville in zone 9b across its 2 ZIP code areas (9b in 95687, the largest). By the same method at Vacaville's NOAA station, the coldest night of a typical year reaches 25°F (22 years, 1991-2020): zone 9b.
How late can frost come in Vacaville?
In half of years the last 32°F night comes after February 18; in one year in ten it comes after March 25. Waiting until March 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Vacaville in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Lake Solano, CA8 miles from this station, 62.9°F a year
- Fairfield, CA9 miles from this station, 61.7°F a year
- Winters, CA11 miles from this station, 62.6°F a year
- Markley Cove, CA12 miles from this station, 60.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made