Photo: Fruitianslip · CC BY-SA 4.0San Joaquin reaches 100° on about 37 days a year, more than 98% of U.S. towns
The coldest hours of a January night bottom out at 39° on average. Precipitation is light here, less than falls on almost every U.S. town. September has warmed most since 1901–2000, part of a 1.6° rise. Seedlings are safe outdoors from about February 27, with the first autumn frost due around November 26.
A year in San Joaquin at a glance
Each month’s typical high and low, and what it brings.
What stands out about San Joaquin’s climate
Compared with towns across the U.S., with San Joaquin’s place in California beside it.
What a year in San Joaquin feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 271 frost-free days a year
In half of years the last 32° night comes by February 27 and the first by November 26. Frost and day counts come from NOAA’s station at Five Points 5 Ssw, CA, 17 miles from the town’s center, 110 ft higher.
The 2023 USDA map puts San Joaquin’s center in zone 9a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 24°. 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 8 inches of rain a year
January is the wettest month and July the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in San Joaquin
53% 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 Five Points 5 Ssw, CA.
Living with San Joaquin’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
271 frost-free days in zone 9a. The last frost comes by Feb 27 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 26.
Months with highs of 62–84° and lows of 40° or more: February, March, April, May, October and November. 0.6 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in San Joaquin from natural hazards, drought is the largest share (82%); heat waves, cold waves, winter storms and ice storms together are 2%. Normals are averages; the hazards page covers the extremes.
Natural hazards →San Joaquin and similar climates
TownRatings has no climate map of the towns around San Joaquin yet.
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 San Joaquin averaged 1.6° warmer than the 1900s. The biggest change is in September (+2.3°).
A bigger shift than in 68% 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 San Joaquin compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with San Joaquin’s place among California’s.
San Joaquin weather by month
Highs, lows and precipitation from NOAA’s grid at San Joaquin’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 56° | 39° | 1.7" | 43° – 52° |
| February | 63° | 42° | 1.6" | 47° – 57° |
| March | 69° | 45° | 1.4" | 51° – 64° |
| April | 75° | 48° | 0.6" | 56° – 65° |
| May | 84° | 54° | 0.4" | 62° – 76° |
| June | 92° | 60° | 0.0" | 71° – 80° |
| July | 97° | 65° | 0.0" | 77° – 85° |
| August | 96° | 64° | 0.0" | 76° – 84° |
| September | 91° | 60° | 0.1" | 71° – 78° |
| October | 80° | 51° | 0.4" | 62° – 70° |
| November | 66° | 43° | 0.6" | 47° – 60° |
| December | 56° | 38° | 1.2" | 44° – 51° |
| Year | 77° | 51° | 8.1" |
How much a month can swing
A normal is an average. May swings the most: from 1991 to 2020 its average ranged from 62° to 76°. September is the most reliable, staying within 7°.
Where San Joaquin’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 San Joaquin’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Five Points 5 Ssw, CA, 17 miles from the town’s center, 110 ft higher; 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 San Joaquin’s climate
What is the weather like in San Joaquin?
A typical July afternoon reaches 97°, a January night drops to 39°. Milder January nights than 87% of U.S. towns; hotter July afternoons than 98% of U.S. towns.
How cold does it get in San Joaquin in winter?
December nights average 38°. About 23 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 44°.
How hot does it get in San Joaquin?
July, with a typical high of 97° and a low of 65°. About 114 days a year reach 90° and 37 reach 100° (Five Points 5 Ssw, CA).
When is the first and last frost in San Joaquin?
In half of years the last spring frost (32°) comes by February 27 and the first fall frost by November 26, about 271 frost-free days, at Five Points 5 Ssw, CA.
What growing zone is San Joaquin in?
Zone 9a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 24°.
What is the best time of year to visit San Joaquin?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March, April, May, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is San Joaquin getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 68% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in San Joaquin.
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.