Gilroy, California climate: Normal weather by month, frost dates and records
Gilroy's normal year runs from 37°F December nights to 87°F August afternoons, with 19.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 15.7°C, December lows of 3°C, August highs of 31°C, 502 mm of precipitation a year.
- NOAA stationGilroy
- Station IDUSC00043417
- Location37.00°N 121.56°W
- Elevation194 ft (59 m)
- From the center1 miles
- Population60,390
On October 22, the normal high in Gilroy is 77°F and the normal low 47°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 Gilroy.
- Jan 61° 38°
- Feb 64° 40°
- Mar 68° 43°
- Apr 72° 45°
- May 77° 49°
- Jun 83° 52°
- Jul 87° 54°
- Aug 87° 54°
- Sep 85° 53°
- Oct 79° 48°
- Nov 68° 42°
- Dec 60° 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 Gilroy each month?
August is the warmest month, with normal highs of 87°F; December the coldest, with normal lows of 37°F. The most precipitation falls in January (4.55 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 | 61°F | 38°F | 49.4°F | 4.55 | 10 | <1 | 5 | 9 h 50 min |
| February | 64°F | 40°F | 52.2°F | 4.27 | 10 | <1 | 2 | 10 h 50 min |
| March | 68°F | 43°F | 55.3°F | 2.59 | 8 | <1 | 1 | 11 h 50 min |
| April | 72°F | 45°F | 58.2°F | 1.30 | 5 | 1 | <1 | 13 h 10 min |
| May | 77°F | 49°F | 63.1°F | 0.56 | 3 | 3 | <1 | 14 h 10 min |
| June | 83°F | 52°F | 67.2°F | 0.15 | 1 | 7 | <1 | 14 h 40 min |
| July | 87°F | 54°F | 70.6°F | 0.00 | <1 | 11 | <1 | 14 h 30 min |
| August | 87°F | 54°F | 70.8°F | 0.03 | <1 | 12 | <1 | 13 h 40 min |
| September | 85°F | 53°F | 68.7°F | 0.04 | 1 | 10 | <1 | 12 h 30 min |
| October | 79°F | 48°F | 63.4°F | 0.85 | 3 | 5 | <1 | 11 h 20 min |
| November | 68°F | 42°F | 55.0°F | 1.74 | 6 | <1 | 2 | 10 h 10 min |
| December | 60°F | 37°F | 48.7°F | 3.69 | 9 | <1 | 7 | 9 h 40 min |
| Year (annual) | 74°F | 46°F | 60.2°F | 19.77 | 55 | 48 | 16 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 16°C | 3°C | 9.7°C | 116 mm |
| February | 18°C | 5°C | 11.2°C | 108 mm |
| March | 20°C | 6°C | 12.9°C | 66 mm |
| April | 22°C | 7°C | 14.6°C | 33 mm |
| May | 25°C | 9°C | 17.3°C | 14 mm |
| June | 28°C | 11°C | 19.6°C | 4 mm |
| July | 31°C | 12°C | 21.4°C | 0 mm |
| August | 31°C | 12°C | 21.6°C | 1 mm |
| September | 29°C | 11°C | 20.4°C | 1 mm |
| October | 26°C | 9°C | 17.4°C | 22 mm |
| November | 20°C | 5°C | 12.8°C | 44 mm |
| December | 16°C | 3°C | 9.3°C | 94 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00043417; 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 Gilroy?
Normal highs sit between 65°F and 85°F in March, April, May, June, September, 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 USC00043417.
When is the last frost in Gilroy?
In Gilroy, the last spring frost (32°F) comes after February 24 in half of years and after April 4 in one year in ten; the first autumn frost comes before November 27 in half of years and before November 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
- February 241 year in 10 after April 4; 9 in 10 after January 23
- First autumn frost, half of years before
- November 271 year in 10 before November 10; 9 in 10 before December 18
NOAA puts the median frost-free season at 277 days, and the season without a hard freeze (28°F) at 333 days.
A hard freeze (28°F) comes after January 16 in half of springs and before December 12 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Gilroy in zone 9b in ZIP code 95020.
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00043417; 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 in Gilroy?
In a normal year in Gilroy, 48 days a year reach 90°F (8 of them 100°F or more), 16 nights fall to 32°F or colder and 55 days bring measurable precipitation.
- Days at 90°F or more
- 48a normal year
- Days at 100°F or more
- 8a normal year
- Nights at 32°F or colder
- 16a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 55a normal year
The highest temperature in this station's record (since 1957) is 115°F, on July 15, 1972; the lowest is 17°F, on December 24, 1990.
The wettest calendar year on that record is 1996, with 36.61 in.
Source: NOAA NCEI 1991-2020 annual normals, station USC00043417; records: ACIS (NOAA Regional Climate Centers), station USC00043417. Records use complete months only; a month missing more than three days is left out.
How sunny is Gilroy?
Over a year 89% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Gilroy, 5.3 kWh per square metre a day. July is the sunniest month (97%) and January the cloudiest (74%). 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 | 74% | 2.4 |
| February | 78% | 3.5 |
| March | 81% | 4.8 |
| April | 85% | 6.2 |
| May | 90% | 7.5 |
| June | 95% | 8.3 |
| July | 97% | 8.2 |
| August | 97% | 7.4 |
| September | 95% | 6.0 |
| October | 91% | 4.4 |
| November | 83% | 2.9 |
| December | 74% | 2.2 |
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 Gilroy need?
A normal year in Gilroy brings 2,424 heating degree days, 55% fewer than the median U.S. place (5,373), and 694 cooling degree days, 24% fewer 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 3,961 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 484 | 0 |
| February | 359 | 0 |
| March | 301 | 1 |
| April | 214 | 10 |
| May | 104 | 47 |
| June | 31 | 97 |
| July | 3 | 177 |
| August | 2 | 182 |
| September | 20 | 131 |
| October | 98 | 47 |
| November | 304 | 2 |
| December | 505 | 0 |
| Year (annual) | 2,424 | 694 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00043417. 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 Gilroy been warmer than normal lately?
2021 averaged 61.8°F, 1.6°F above the 1991-2020 normal of 60.2°F.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 61.8°F | +1.6°F | 17.29 |
Source: observed years: ACIS, station USC00043417. A year counts only with all twelve months complete.
How does Gilroy's climate compare?
Gilroy is warmer than 99 of the other 218 places with their own NOAA record in California, and wetter than 133. Across the 7,247 U.S. stations with normals, its annual mean of 60.2°F is warmer than 75%.
In the Köppen classification computed from these normals, Gilroy 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 Gilroy 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.
- Morgan Hill, CA45,952 people · 10 mi NW
- San Martin, CA7,199 people · 6 mi N
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 Gilroy's climate
What is the coldest month in Gilroy?
December, with a normal high of 60°F and a normal low of 37°F. The warmest is August (87°F by day, 54°F at night).
Does it snow in Gilroy?
Rarely: NOAA's normal is no measurable snow a year.
What is the rainiest month in Gilroy?
January, with 4.55 in of precipitation in a normal year; the driest is July with 0.00 in.
What plant hardiness zone is Gilroy in?
The USDA's 2023 map puts Gilroy in zone 9b in ZIP code 95020.
How late can frost come in Gilroy?
In half of years the last 32°F night comes after February 24; in one year in ten it comes after April 4. Waiting until April 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Gilroy in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Watsonville Water Works, CA12 miles from this station, 57.6°F a year
- Hollister, CA13 miles from this station, 58.6°F a year
- Watsonville, CA14 miles from this station, 57.2°F a year
- Paicines (4 mi W), CA23 miles from this station, 56.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made