Point Forecast: 3 Miles S Portola Valley CA  37.33N 122.21W (Elev. 2231 ft)	Last Update: 3:16 am PDT Sep 9, 2026

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Weather Elements Weather/Precipitation Temperature (°F) Dewpoint (°F) Heat Index (°F) Surface Wind  ktmphkm/hm/s Sky Cover (%) Precipitation Potential (%) Relative Humidity (%) Rain Thunder Fog Trans. Wind  ktmphkm/hm/s 20ft Wind  ktmphkm/hm/s

48-Hour Period Starting: 5am Wed, Sep 9 20266am Wed, Sep 9 20267am Wed, Sep 9 20268am Wed, Sep 9 20269am Wed, Sep 9 202610am Wed, Sep 9 202611am Wed, Sep 9 202612pm Wed, Sep 9 20261pm Wed, Sep 9 20262pm Wed, Sep 9 20263pm Wed, Sep 9 20264pm Wed, Sep 9 20265pm Wed, Sep 9 20266pm Wed, Sep 9 20267pm Wed, Sep 9 20268pm Wed, Sep 9 20269pm Wed, Sep 9 202610pm Wed, Sep 9 202611pm Wed, Sep 9 202612am Thu, Sep 10 20261am Thu, Sep 10 20262am Thu, Sep 10 20263am Thu, Sep 10 20264am Thu, Sep 10 20265am Thu, Sep 10 20266am Thu, Sep 10 20267am Thu, Sep 10 20268am Thu, Sep 10 20269am Thu, Sep 10 202610am Thu, Sep 10 202611am Thu, Sep 10 202612pm Thu, Sep 10 20261pm Thu, Sep 10 20262pm Thu, Sep 10 20263pm Thu, Sep 10 20264pm Thu, Sep 10 20265pm Thu, Sep 10 20266pm Thu, Sep 10 20267pm Thu, Sep 10 20268pm Thu, Sep 10 20269pm Thu, Sep 10 202610pm Thu, Sep 10 202611pm Thu, Sep 10 202612am Fri, Sep 11 20261am Fri, Sep 11 20262am Fri, Sep 11 20263am Fri, Sep 11 20264am Fri, Sep 11 20265am Fri, Sep 11 20266am Fri, Sep 11 20267am Fri, Sep 11 20268am Fri, Sep 11 20269am Fri, Sep 11 202610am Fri, Sep 11 202611am Fri, Sep 11 202612pm Fri, Sep 11 20261pm Fri, Sep 11 20262pm Fri, Sep 11 20263pm Fri, Sep 11 20264pm Fri, Sep 11 20265pm Fri, Sep 11 20266pm Fri, Sep 11 20267pm Fri, Sep 11 20268pm Fri, Sep 11 20269pm Fri, Sep 11 202610pm Fri, Sep 11 202611pm Fri, Sep 11 202612am Sat, Sep 12 20261am Sat, Sep 12 20262am Sat, Sep 12 20263am Sat, Sep 12 20264am Sat, Sep 12 20265am Sat, Sep 12 20266am Sat, Sep 12 20267am Sat, Sep 12 20268am Sat, Sep 12 20269am Sat, Sep 12 202610am Sat, Sep 12 202611am Sat, Sep 12 202612pm Sat, Sep 12 20261pm Sat, Sep 12 20262pm Sat, Sep 12 20263pm Sat, Sep 12 20264pm Sat, Sep 12 20265pm Sat, Sep 12 20266pm Sat, Sep 12 20267pm Sat, Sep 12 20268pm Sat, Sep 12 20269pm Sat, Sep 12 202610pm Sat, Sep 12 202611pm Sat, Sep 12 202612am Sun, Sep 13 20261am Sun, Sep 13 20262am Sun, Sep 13 20263am Sun, Sep 13 20264am Sun, Sep 13 20265am Sun, Sep 13 20266am Sun, Sep 13 20267am Sun, Sep 13 20268am Sun, Sep 13 20269am Sun, Sep 13 202610am Sun, Sep 13 202611am Sun, Sep 13 202612pm Sun, Sep 13 20261pm Sun, Sep 13 20262pm Sun, Sep 13 20263pm Sun, Sep 13 20264pm Sun, Sep 13 2026

Date	09/09																			09/10
Hour (PDT)	05	06	07	08	09	10	11	12	13	14	15	16	17	18	19	20	21	22	23	00	01	02	03	04
Temperature (°F)	73	74	74	75	77	79	81	84	85	86	88	86	86	85	81	79	79	79	79	80	79	79	78	76
Dewpoint (°F)	38	37	37	37	41	42	45	49	48	48	50	49	49	48	45	41	38	36	35	35	35	35	36	36
Heat Index (°F)				75	77	79	80	82	83	84	85	84	84	82	80	79	78	78	78	78	78	79	78	76
Surface Wind (mph)	3	3	3	5	3	2	2	2	3	3	5	7	7	6	6	5	5	5	5	3	3	3	3	3
Wind Dir	ENE	ENE	ENE	ENE	ENE	ENE	NE	NE	NNE	NNE	N	N	N	NNW	NW	NW	NW	NNW	NNW	NNW	NNW	NW	NNW	NW
Gust
Sky Cover (%)	44	61	57	59	49	32	21	16	18	21	14	11	19	28	18	20	9	4	12	7	14	22	16	21
Precipitation Potential (%)	0	0	0	0	0	1	0	0	1	1	1	1	3	3	3	3	3	2	2	2	2	2	2	2
Relative Humidity (%)	28	26	27	26	28	26	28	30	28	26	27	28	28	28	29	26	23	22	20	20	20	20	22	23
Rain	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--
Thunder	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--
Date																				09/11
Hour (PDT)	05	06	07	08	09	10	11	12	13	14	15	16	17	18	19	20	21	22	23	00	01	02	03	04
Temperature (°F)	75	75	74	75	76	78	80	81	82	84	83	83	82	81	79	77	76	76	76	76	75	75	74	74
Dewpoint (°F)	37	37	38	38	41	44	50	53	53	53	51	52	51	51	50	48	46	44	43	43	43	44	45	46
Heat Index (°F)	75	75		75	76	78	79	80	81	82	82	81	81	80	79	77	76	76	76	76	75	75
Surface Wind (mph)	3	3	3	3	3	3	5	5	5	6	6	6	6	6	6	5	5	5	5	5	5	5	5	5
Wind Dir	WNW	WNW	WNW	W	W	W	WNW	WNW	WNW	WNW	WNW	WNW	WNW	WNW	WNW	W	W	W	W	W	W	W	W	W
Gust
Sky Cover (%)	47	47	47	47	47	47	25	25	25	19	19	19	15	15	15	18	18	18	16	16	16	8	8	8
Precipitation Potential (%)	3	3	2	0	0	0	0	0	0	0	0	0	1	1	1	1	1	1	0	0	0	0	0	0
Relative Humidity (%)	25	25	27	26	29	30	36	38	36	34	33	34	34	35	36	36	34	32	31	31	31	33	35	37
Rain	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--
Thunder	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--	--

International System of Units Forecast Discussion 7-Day Forecast Hourly Weather Graph River Stage Summary 24 Hour Precipitation Summary NWS Office Map