• Early AM

    Oct 20

    Lo 58°

    Increasing clouds

    Bicycling Weather
    • Precip
      13%
    • Hours of Precip
      0
    • Wind
      Gust
      10 mph
    more
  • Today

    Oct 20

    69°Lo 52°

    A little afternoon rain

    Excellent for biking
    • Precip
      55%
    • Hours of Precip
      1
    • Wind
      Gust
      17 mph
    more
  • Tue

    Oct 21

    70°Lo 53°

    Partly sunny

    Excellent for biking
    • Precip
      6%
    • Hours of Precip
      0
    • Wind
      Gust
      15 mph
  • Wed

    Oct 22

    72°Lo 56°

    Mostly sunny and pleasant

    Excellent for biking
    • Precip
      6%
    • Hours of Precip
      0
    • Wind
      Gust
      12 mph
    more
  • Thu

    Oct 23

    73°Lo 57°

    Pleasant with plenty of sun

    Excellent for biking
    • Precip
      25%
    • Hours of Precip
      0
    • Wind
      Gust
      10 mph
    more
Next Previous
< Previous 8 hours Next 8 hours >
  Tue
9am
10am 11am 12pm 1pm 2pm 3pm 4pm
  9am 10am 11am 12pm 1pm 2pm 3pm 4pm
Forecast
Mostly Sunny
Mostly Sunny
Mostly Sunny
Mostly Sunny
Mostly Sunny
Mostly Sunny
Mostly Sunny
Mostly Sunny
Temp (°F) 56° 59° 62° 65° 66° 67° 68° 70°
RealFeel® 56° 60° 65° 68° 67° 67° 67° 67°
Humidity 80% 71% 64% 58% 55% 51% 49% 49%
   
  9am 10am 11am 12pm 1pm 2pm 3pm 4pm
Rain
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
Snow
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
Ice
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
 
0%
   
  9am 10am 11am 12pm 1pm 2pm 3pm 4pm
Wind (mph) 5 NNW 6 NNW 6 NW 7 NW 9 WNW 10 WNW 10 WNW 10 WNW
UV Index 1 2 3 4 4 4 3 2
Cloud Cover 26% 26% 26% 26% 26% 26% 26% 26%
Dew Point 50° 50° 50° 50° 49° 48° 49° 50°
Middle Grid line 75 F Middle Grid line 70 F Middle Grid line 65 F Middle Grid line 60 F Middle Grid line 55 F

Temperature History - Oct 21

more Historical Weather Data >
  Today Normal Record 10/21/2013
High 70° N/A N/A 71°
Low 53° N/A N/A 48°

Sunrise/Sunset

Sunrise / Sunset Illustration

Rises at 7:22 AM with 11:01 of sunlight, then sets at 6:23 PM

Moonrise/Moonset

Astronomy >
Moonrise / Moonset Illustration

Rises at 5:14 AM with 12:04 of moolight, then sets at 5:18 PM

Castro Valley Weather Report

Rain to Arrive in San Francisco Early This Week

October 20, 2014; 4:44 AM ET

A chance of rain is expected on Monday as a Pacific storm moves through the Northwest United States. more >

Is Your Outdoor Gear Waterproof?

Dec 5, 2012; 5:00 AM ET Now that it's cold enough to hit the slopes, you may want to look more closely at what materials your winter sports gear is made of. As it turns out, not all waterproofing is created equal.