Portola Valley, California Weather
Summer heat deepens across the valleys. Day 15 of summer. Read this microseason across nine climate regions →
Portola Valley weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 5Foggy——74°56°—
- MondayJul 6Overcast——70°52°-4°
- TuesdayJul 7Overcast——75°49°+5°
- WednesdayJul 8Overcast——79°50°+4°
- ThursdayJul 9Overcast——80°49°+1°
- FridayJul 10Overcast——85°49°+5°
- SaturdayJul 11Overcast——93°53°+8°
AQI 24 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 4.9 µg/m³ (AQI 27) with a 0.62 fine-to-coarse ratio and 3 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 4.9 µg/m³ (AQI 27) with a 0.62 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.62
- 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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 11:28 PM
- Moonset
- 11:27 AM
- In sign
- ♓︎ Pisces
Summer heat deepens across the valleys
Portola Valley at a glance
- Today vs. normal: 3°F below the seasonal normal for this latitude
- Last frost: March 31 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 94028
16-Day Forecast — Portola Valley
- Sun74°56°2%
- Mon70°52°0%
- Tue75°49°0%
- Wed79°50°1%
- Thu80°49°0%
- Fri85°49°0%
- Sat93°53°0%
- Sun82°59°1%
- Mon91°56°2%
- Tue90°53°5%
- Wed88°53°1%
- Thu91°52°3%
- Fri95°54°0%
- Sat89°53°0%
- Sun84°50°3%
- Mon84°49°3%
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 Portola Valley
- 94028