San Leandro, California Weather
Coastal fog thickens at dawn. Day 77 of spring. Read this microseason across nine climate regions →
San Leandro weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Foggy——75°55°—
- FridayJun 5Overcast——81°54°+6°
- SaturdayJun 6Overcast——65°54°-16°
- SundayJun 7Overcast——67°53°+2°
- MondayJun 8Heavy Drizzle14%0.37″61°54°-6°
- TuesdayJun 9Heavy Drizzle20%0.14″63°55°+2°
- WednesdayJun 10Partly Cloudy——74°55°+11°
PM2.5 at 7.6 µg/m³ (AQI 42) with a 0.73 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust. AQI down 7 over the last 6 hours (steady decline since this morning).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 33 now. With UV 9.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 40 by mid-afternoon.
- Present
- AQI 33
- UV peak
- 9.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 40
PM × Wind × Precip
PM2.5 at 7.6 µg/m³ (AQI 42) with a 0.73 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.73
- Wind
- light
- 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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 6:34 AM
- Moonset
- 4:23 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
San Leandro at a glance
- Today vs. normal: 9°F below the seasonal normal for this latitude
- Last frost: April 2 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
September is San Leandro's warmest month, with a mean temperature near 66°F, and December is its coldest at roughly 52°F. Rainfall peaks in December at 4.7 inches and drops to 0.0 inches in July.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 53° | 4.3″ | 8 |
| February | 55° | 4.3″ | 7 |
| March | 57° | 3.2″ | 7 |
| April | 59° | 1.4″ | 4 |
| May | 61° | 0.8″ | 2 |
| June | 63° | 0.2″ | 1 |
| July | 64° | 0.0″ | 0 |
| August | 65° | 0.1″ | 0 |
| September | 66° | 0.1″ | 0 |
| October | 64° | 1.1″ | 2 |
| November | 58° | 2.4″ | 4 |
| December | 52° | 4.7″ | 8 |
Regional context
San Leandro sits within a hot-summer Mediterranean climate region, a cohort sharing similar temperature ranges, seasonal patterns, and growing conditions with nearby cities.
Similar climates: Los Angeles, CA, San Francisco, CA, San Diego, CA, Riverside, CA, Sacramento, CA.
Naturalist notes
In late spring, valley oaks at this latitude are leafing out fully and their new leaves shift from pale green to leathery dark green by early May.
Barn swallows return to the East Bay in numbers by late April and can be seen skimming low over the San Leandro Creek corridor, hawking insects on warm afternoons.
Frequently asked
- When does it freeze in San Leandro?
- San Leandro's last spring frost typically arrives around mid-April, and the first fall frost around mid-November.
- What is the rainy season in San Leandro?
- December is the wettest month with about 4.7 inches of rain on average; the city receives roughly 23 inches annually.
- What is the warmest month in San Leandro?
- September is typically warmest, averaging about 66°F.
- What is the coldest month in San Leandro?
- December is typically coldest, averaging about 52°F.
- When can I start a vegetable garden in San Leandro?
- Cool-season crops such as peas and lettuce can be sown around the last spring frost in mid-April; warm-season crops like tomatoes and peppers wait until 1–2 weeks after.
- How many rainy days does San Leandro get?
- San Leandro averages about 42 rainy days per year.
- What hardiness zone is San Leandro?
- San Leandro's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
San Leandro, California falls within a hot-summer Mediterranean climate zone. January temperatures hover near 53°F and July averages 64°F, a seasonal swing of 12°F.
The city receives about 23 inches of precipitation over roughly 42 rainy days across the year.
Latitude (37.7°N), proximity to large water bodies, and elevation all set the rhythm of the year. These factors determine what grows, when frost is likely, and the shape of daily weather.