Portola Valley, CA Weather Forecast | 5 Day
Updated: Fri Sep 18th 2026 3:30 AM PDT
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Sunny
Fri 9-18-26
Sunny with a high of 72°F and a low of 57°F. There's a very small chance of rainfall, only about 7%. Winds will be light at 10mph and gusts of 18.1mph at 12 PM. The humidity will be on the higher side, averaging about 75%, the maximum being 92% at 11 PM and 47% being its lowest at 3 PM. Barometric pressure is its highest of 30.12inHg at 8 AM, a lowest point of 30.01inHg at 5 PM with an avg 30.07inHg.
- HI: 72°F
- LO: 57°F
- Rainfall: 7%
- Snowfall: 0%
- Wind
9.2 mph - Humidity
75% avg. - UV Index
6.9 - Air QualityGood
- Sunrise
06:53 AM - Sunset
07:12 PM - Moonrise
02:59 PM - Moonset
Does not set today - Moon Phase
First Quarter
Sunny
Weather Tomorrow, Sat 9-19-26
Sunny with a high of 72°F and a low of 55°F. There's a very small chance of rainfall, only about 10%. Winds will be light at 9mph and gusts of 19mph at 2 PM. The humidity will be on the higher side, averaging about 77%, the maximum being 93% at 4 AM and 50% being its lowest at 3 PM. Barometric pressure is its highest of 30.02inHg at 12 AM, a lowest point of 29.92inHg at 5 PM with an avg 29.97inHg.
- HI: 72°F
- LO: 55°F
- Rainfall: 10%
- Snowfall: 0%
- Wind
8.7 mph - Humidity
77% avg. - UV Index
7.2 - Air QualityGood
- Sunrise
06:54 AM - Sunset
07:11 PM - Moonrise
03:44 PM - Moonset
12:07 AM - Moon Phase
First Quarter
Sunny
Sun 9-20-26
Sunny with a high of 67°F and a low of 55°F. There might be light rainfall having a 15% chance. Winds will be light at 10mph and gusts of 13.6mph at 12 PM. The humidity will be on the higher side, averaging about 79%, the maximum being 91% at 4 AM and 58% being its lowest at 1 PM. Barometric pressure is its highest of 29.97inHg at 10 AM, a lowest point of 29.91inHg at 5 PM with an avg 29.94inHg.
- HI: 67°F
- LO: 55°F
- Rainfall: 15%
- Snowfall: 0%
- Wind
9.2 mph - Humidity
79% avg. - UV Index
5.5 - Air QualityGood
- Sunrise
06:55 AM - Sunset
07:09 PM - Moonrise
04:22 PM - Moonset
01:06 AM - Moon Phase
Waxing Gibbous
Sunny
Mon 9-21-26
Sunny with a high of 70°F and a low of 55°F. There's a very small chance of rainfall, only about 10%. Winds will be light at 8mph and gusts of 16.6mph at 8 PM. The humidity will be on the higher side, averaging about 76%, the maximum being 91% at 10 PM and 52% being its lowest at 3 PM. Barometric pressure is its highest of 29.95inHg at 12 AM, a lowest point of 29.87inHg at 5 PM with an avg 29.92inHg.
- HI: 70°F
- LO: 55°F
- Rainfall: 10%
- Snowfall: 0%
- Wind
7.6 mph - Humidity
76% avg. - UV Index
6.3 - Air QualityGood
- Sunrise
06:55 AM - Sunset
07:07 PM - Moonrise
04:54 PM - Moonset
02:06 AM - Moon Phase
Waxing Gibbous
Sunny
Tue 9-22-26
Sunny with a high of 73°F and a low of 56°F. There's a very small chance of rainfall, only about 8%. Winds will be light at 8mph and gusts of 14.8mph at 11 AM. The humidity will be on the higher side, averaging about 71%, the maximum being 92% at 12 AM and 48% being its lowest at 12 PM. Barometric pressure is its highest of 29.92inHg at 8 AM, a lowest point of 29.82inHg at 5 PM with an avg 29.88inHg.
- HI: 73°F
- LO: 56°F
- Rainfall: 8%
- Snowfall: 0%
- Wind
7.8 mph - Humidity
71% avg. - UV Index
6 - Air QualityGood
- Sunrise
06:56 AM - Sunset
07:06 PM - Moonrise
05:22 PM - Moonset
03:07 AM - Moon Phase
Waxing Gibbous
Overcast
Wed 9-23-26
Overcast with a high of 81°F and a low of 62°F. There might be light rainfall having a 13% chance. Winds will be light at 8mph and gusts of 13.4mph at 11 AM. Humidity levels should be comfortable, sitting around 57% on average, the maximum being 75% at 12 AM and 37% being its lowest at 2 PM. Barometric pressure is its highest of 29.88inHg at 11 AM, a lowest point of 29.83inHg at 5 PM with an avg 29.86inHg.
- HI: 81°F
- LO: 62°F
- Rainfall: 13%
- Snowfall: 0%
- Wind
7.2 mph - Humidity
57% avg. - UV Index
6 - Air QualityTBA
- Sunrise
06:57 AM - Sunset
07:04 PM - Moonrise
05:46 PM - Moonset
04:07 AM - Moon Phase
Waxing Gibbous
This 5-Day weather forecast is valid for ZIP code 94028, accurately covering the area of Portola Valley, CA.
Currently
 |
58°F |
30.09 inHg.
Barometer 89%
Humidity SW 4.7 mph Wind |
| Clear | ||
National Outlook
More Flash Flooding Expected in the Southwest and Plains: 09-17 to 09-19
Thu Sep 17th 2026, 5:06am PDT
Read
Rain and Storms Hit Midwest and East, Monsoon in the South 09-19 to 09-23
Extended Forecast
Thu Sep 17th 2026, 5:10am PDT
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Thu Sep 17th 2026, 5:10am PDT
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