Foster City, California Weather
Summer heat deepens across the valleys. Day 15 of summer. Read this microseason across nine climate regions →
Foster City weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 5Overcast——71°55°—
- MondayJul 6Overcast——68°52°-3°
- TuesdayJul 7Overcast——71°55°+3°
- WednesdayJul 8Mostly Clear——77°57°+6°
- ThursdayJul 9Overcast——78°59°+1°
- FridayJul 10Overcast——82°56°+4°
- SaturdayJul 11Overcast——83°60°+1°
AQI 26 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 4.5 µg/m³ (AQI 25) with a 0.66 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm 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 4.5 µg/m³ (AQI 25) with a 0.66 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.66
- 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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 11:28 PM
- Moonset
- 11:28 AM
- In sign
- ♓︎ Pisces
Summer heat deepens across the valleys
Foster City at a glance
- Today vs. normal: 8°F below the seasonal normal for this latitude
- Last frost: April 1 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
16-Day Forecast — Foster City
- Sun71°55°0%
- Mon68°52°0%
- Tue71°55°1%
- Wed77°57°0%
- Thu78°59°0%
- Fri82°56°0%
- Sat83°60°0%
- Sun76°63°1%
- Mon90°67°2%
- Tue89°61°6%
- Wed84°60°1%
- Thu89°61°2%
- Fri94°64°0%
- Sat87°62°0%
- Sun83°60°3%
- Mon84°59°6%
Forecast data from Open-Meteo (CC BY 4.0).
Right now in the garden
Peak growing season
As of July 5, 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.
ZIP codes in Foster City
- 94404