San Jose, California Weather
Ceanothus blooms again. Day 93 of summer. Read this microseason across nine climate regions →
San Jose weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 2:41 AM PDT · Open-Meteo
- TodaySep 21Clear later——75°57°—
- TuesdaySep 22Mostly Clear——80°56°+5°
- WednesdaySep 23Overcast——90°61°+10°
- ThursdaySep 24Overcast——87°64°-3°
- FridaySep 25Overcast——84°61°-3°
- SaturdaySep 26Overcast——87°62°+3°
- SundaySep 27Overcast——86°59°-1°
Air quality now AQI 50 · Good
AQI 50 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 8.0 µg/m³ (AQI 44) with a 0.73 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in stagnant air, not road dust.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 8.0 µg/m³ (AQI 44) with a 0.73 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in stagnant air, not road dust.
- PM2.5/PM10
- 0.73
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:36 PM
- Moonset
- 1:43 AM
- In sign
- ♑︎ Capricorn
Ceanothus blooms again
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
San Jose at a glance
- Today vs. normal: Today averages 66°F (high 75°F, low 57°F), 5°F below the 71°F normal for Sep 21
- Last frost: January 2 (1991–2020 median, NOAA station 7 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant tomatoes, peppers, beans, squash; harvest tomatoes, peppers, beans, summer squash, winter squash
15-Day Forecast — San Jose
- Mon75°56°1%
- Tue80°56°1%
- Wed90°61°0%
- Thu87°64°0%
- Fri84°61°1%
- Sat87°62°0%
- Sun86°59°1%
- Mon91°61°1%
- Tue96°68°1%
- Wed76°64°2%
- Thu85°64°0%
- Fri85°61°3%
- Sat82°58°6%
- Sun86°59°6%
- Mon87°67°6%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near San Jose
Interactive wind and temperature map centered on San Jose — it loads in your browser. Open the full weather map.
Right now in the garden
Peak growing season
As of September 21, the growing season is at its peak — the first frost (around December 25) is weeks away. Fall transplants go in about 10–12 weeks before the first frost, October 2 to October 16 here. This city's planting calendar for September: plant tomatoes, peppers, beans, and squash; harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in San Jose
San Jose sits in Santa Clara County, where the year’s longest day runs 14h 44m of daylight and its shortest just 9h 35m — a swing of +5h 9m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Los Angeles, the state’s largest city, lies about 293 miles to the SE. The nearest town San Jose tracks is Santa Clara, roughly 8 miles to the WNW.
Air quality in San Jose
Air quality in San Jose’s county has trended cleaner since 2020; its cleanest year on record was 2023 (median AQI 43). See the full air-quality history for San Jose.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | lettuce, peas, spinach, radishes | lettuce, spinach, radishes, fall brassicas, carrots |
| February | — | lettuce, peas, spinach, radishes |
| March | — | lettuce, peas, spinach |
| April | tomatoes, peppers, beans, squash | — |
| May | tomatoes, peppers, beans, squash | garlic |
| June | beans, squash | beans, summer squash |
| July | beans, squash | tomatoes, peppers, beans, summer squash |
| August | tomatoes, peppers, beans, squash | tomatoes, peppers, beans, summer squash, winter squash |
| September | tomatoes, peppers, beans, squash | tomatoes, peppers, beans, summer squash, winter squash |
| October | beans, squash, fall brassicas, carrots | tomatoes, peppers, beans, summer squash, winter squash |
| November | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| December | lettuce, peas, spinach, radishes, garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
A year in weather
San Jose's warmest month is August (~73°F mean) and its coldest is January (~51°F). Rainfall peaks in January (4.2 inches) and bottoms out in July (0.0 inches).
| Month | Mean temp | Precip |
|---|---|---|
| January | 51° | 4.2″ |
| February | 53° | 3.8″ |
| March | 55° | 3.4″ |
| April | 59° | 1.7″ |
| May | 64° | 0.6″ |
| June | 69° | 0.1″ |
| July | 73° | 0.0″ |
| August | 73° | 0.1″ |
| September | 72° | 0.1″ |
| October | 67° | 0.7″ |
| November | 58° | 2.5″ |
| December | 51° | 3.6″ |
Regional context
Similar climates Fruitdale, CA, Alum Rock, CA, Cambrian Park, CA
Drawing on modelled 1991-2020 normals (EC_Earth3P_HR model via Open-Meteo), San Jose's January averages 51°F and July 73°F — 22°F apart — while precipitation totals roughly 20.8 inches.
Cool-season fronts carry San Jose's rain: January logs 4.2 inches, against July's 0.0 inches — winter does the heavy lifting in San Jose. It is a winter-storm rhythm San Jose shares with places like Fruitdale, CA, Alum Rock, CA and Cambrian Park, CA.
San Jose's growing window opens around January 2, once San Jose's overnight lows stop freezing — sow lettuce, chard, arugula, and mustard greens. Warm-soil crops in San Jose wait about two weeks past San Jose's last frost, once the soil warms. Around December 25, freezing nights resume in San Jose and tender crops must come in. Sheltered San Jose yards can escape a light frost.
Similar climates: Fruitdale, CA, Alum Rock, CA, Cambrian Park, CA, East Foothills, CA, Campbell, CA.
Frequently asked
- When does it freeze in San Jose?
- San Jose's last spring frost lands near January 2, and in San Jose the first fall frost follows around December 25.
- What is the rainy season in San Jose?
- San Jose sees its heaviest rain in January (around 4.2 inches), part of roughly 21 inches a year.
- What is the warmest month in San Jose?
- On average August tops the year in San Jose at about 73°F.
- What is the coldest month in San Jose?
- The coldest stretch in San Jose falls in January, around 51°F on average.
- When can I start a vegetable garden in San Jose?
- Around January 2, start frost-hardy crops in San Jose; tomatoes and basil belong a fortnight later.
- What hardiness zone is San Jose?
- With January around 51°F, San Jose's zone reflects that minimum — the USDA ZIP map confirms San Jose's band.
- What is the 10-day forecast for San Jose?
- San Jose's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in San Jose?
- See this week's day-by-day rain chances for San Jose in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in San Jose?
- Current conditions for San Jose and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the San Jose forecast updated?
- The San Jose forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in San Jose?
- Today's sunrise and sunset times for San Jose are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for San Jose?
- The next few days in San Jose's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
San Jose sits at 37.3°N; its climate zone is hot-summer Mediterranean (Köppen approximation).
ZIP codes in San Jose
- 95002
- 95008
- 95013
- 95037
- 95101
- 95103
- 95106
- 95109
- 95110
- 95111
- 95112
- 95113
- 95115
- 95116
- 95117
- 95118
- 95119
- 95120
- 95121
- 95122
- 95123
- 95124
- 95125
- 95126
- 95127
- 95128
- 95129
- 95130
- 95131
- 95132
- 95133
- 95134
- 95135
- 95136
- 95138
- 95139
- 95141
- 95148
- 95150
- 95151
- 95153
- 95154
- 95155
- 95156
- 95157
- 95158
- 95159
- 95160
- 95161
- 95164
- 95172
- 95173
- 95190
- 95191
- 95192
- 95193
- 95194
- 95196