Photo: Sanfranman59 · CC BY-SA 3.0Dry weather: only 21 inches of rain and melted snow a year in Gilroy, less than in 89% of U.S. towns
January nights here settle around 39°. Expect the heaviest rain or snow in January and the lightest in July. Winters are mild: January nights here are milder than in 87% of U.S. towns. Picnics, hikes and garden evenings come into their own from February to November, with highs of 64–83°.
A year in Gilroy at a glance
Each month’s typical high and low, and what it brings.
What stands out about Gilroy’s climate
Compared with towns across the U.S., with Gilroy’s place in California beside it.
What a year in Gilroy feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 277 frost-free days a year
In half of years the last 32° night comes by February 24 and the first by November 27. Frost and day counts come from NOAA’s station at Gilroy, CA, 1.4 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Gilroy’s center in zone 9b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 26°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 21 inches of rain a year
January is the wettest month and July the driest. Rain falls on about 55 days a year. Snow is rare: about 0.0" in a normal year at Gilroy, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Gilroy
78% of the work is heating. Months averaging under 55° run from November through February.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Gilroy, CA.
Living with Gilroy’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
277 frost-free days in zone 9b. The last frost comes by Feb 24 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 27.
Months with highs of 62–84° and lows of 40° or more: February, March, April, May, June, July, August, September, October and November. 19 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Gilroy from natural hazards, earthquakes are the largest share (61%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Gilroy and similar climates
TownRatings has no climate map of the towns around Gilroy yet.
Climates most like Gilroy’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Gilroy, CA | 39° | 82° | 21" | 0.0" |
| Green, OR | 37° | 86° | 32" | 0.0" |
| Mercer Island, WA | 37° | 77° | 37" | 3.8" |
| Alpine, TX | 30° | 90° | 15" | 2.2" |
| Sierra Vista Southeast, AZ | 32° | 91° | 15" | 0.7" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Gilroy averaged 1.9° warmer than the 1900s. The biggest change is in January (+2.9°).
A bigger shift than in 84% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Gilroy compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Gilroy’s place among California’s.
Gilroy weather by month
Highs, lows and precipitation from NOAA’s grid at Gilroy’s center; snow, wet days and snow on the ground from Gilroy, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 61° | 39° | 4.5" | 0.0" | 10 | 0 | 46° – 54° |
| February | 64° | 41° | 4.1" | 0.0" | 10 | 0 | 49° – 58° |
| March | 67° | 43° | 3.4" | 0.0" | 8 | 0 | 50° – 61° |
| April | 71° | 45° | 1.4" | 0.0" | 5 | 0 | 54° – 62° |
| May | 75° | 49° | 0.6" | 0.0" | 3 | 0 | 58° – 67° |
| June | 80° | 53° | 0.1" | 0.0" | 1 | 0 | 63° – 69° |
| July | 82° | 55° | 0.0" | 0.0" | 0 | 0 | 66° – 72° |
| August | 83° | 55° | 0.1" | 0.0" | 0 | 0 | 66° – 72° |
| September | 82° | 53° | 0.1" | 0.0" | 1 | 0 | 65° – 72° |
| October | 78° | 49° | 0.9" | 0.0" | 3 | 0 | 60° – 68° |
| November | 68° | 42° | 1.9" | 0.0" | 6 | 0 | 48° – 59° |
| December | 60° | 38° | 4.0" | 0.0" | 9 | 0 | 45° – 53° |
| Year | 72° | 47° | 20.9" | 0.0" | 55 | 0 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 48° to 59°. August is the most reliable, staying within 6°.
Where Gilroy’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Gilroy’s center.
- Snow: Gilroy, CA (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Gilroy, CA, 1.4 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Gilroy’s climate
What is the weather like in Gilroy?
A typical July afternoon reaches 82°, a January night drops to 39°, and snow is almost unheard of. Milder January nights than 87% of U.S. towns; cooler July afternoons than 79% of U.S. towns.
How cold does it get in Gilroy in winter?
December nights average 38°. About 16 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 45°.
How much snow does Gilroy get?
About 0.0 inches in a normal winter at Gilroy, CA, so most winters see none.
How hot does it get in Gilroy?
July, with a typical high of 82° and a low of 55°. About 48 days a year reach 90° and 8 reach 100° (Gilroy, CA).
When is the first and last frost in Gilroy?
In half of years the last spring frost (32°) comes by February 24 and the first fall frost by November 27, about 277 frost-free days, at Gilroy, CA.
What growing zone is Gilroy in?
Zone 9b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 26°.
What is the best time of year to visit Gilroy?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March, April, May, June, July, August, September, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Gilroy getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 84% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Gilroy.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.