• Tonight

    Jul 30

    Lo 56°

    Low clouds, fog forming

    Ragweed Pollen Weather
    • Grass
      Pollen
      1 - Low
    • Ragweed
      Pollen
      1 - Low
    • Tree
      Pollen
      1 - Low
    more
  • Sun

    Jul 31

    79°Lo 58°

    Clouds, then sun

    Low ragweed pollen levels
    • Grass
      Pollen
      1 - Low
    • Ragweed
      Pollen
      1 - Low
    • Tree
      Pollen
      1 - Low
    more
  • Mon

    Aug 1

    78°Lo 56°

    Areas of fog, then sun

    Low ragweed pollen levels
    • Grass
      Pollen
      1 - Low
    • Ragweed
      Pollen
      1 - Low
    • Tree
      Pollen
      1 - Low
  • Tue

    Aug 2

    79°Lo 54°

    Mostly sunny and nice

    Low ragweed pollen levels
    • Grass
      Pollen
      1 - Low
    • Ragweed
      Pollen
      1 - Low
    • Tree
      Pollen
      1 - Low
    more
  • Wed

    Aug 3

    81°Lo 55°

    Fog to sun

    Low ragweed pollen levels
    • Grass
      Pollen
      1 - Low
    • Ragweed
      Pollen
      1 - Low
    • Tree
      Pollen
      1 - Low
    more
Next Previous
Hi 78° RealFeel® 82° Precipitation 2%

Day

N

E

S

W

  • W 9 mph
  • Gusts: 15 mph

Areas of low clouds and fog, then sunshine

  • Max UV Index: 8 (Very High)
  • Thunderstorms: 0%
  • Precipitation: 0 in
  • Rain: 0 in
  • Snow: 0 in
  • Ice: 0 in
  • Hours of Precipitation: 0 hrs
  • Hours of Rain: 0 hrs
Lo 56° RealFeel® 55° Precipitation 2%

Night

N

E

S

W

  • W 6 mph
  • Gusts: 13 mph

Mainly clear early on, then areas of low clouds and fog

  • Max UV Index: N/A
  • Thunderstorms: 1%
  • Precipitation: 0 in
  • Rain: 0 in
  • Snow: 0 in
  • Ice: 0 in
  • Hours of Precipitation: 0 hrs
  • Hours of Rain: 0 hrs

Temperature History - Aug 1

more Historical Weather Data >
  Today Normal Record 8/1/2015
High 78° 78° N/A 78°
Low 56° 57° N/A 61°

Sunrise/Sunset

Sunrise / Sunset Illustration

Rises at 6:13 AM with 14:03 of sunlight, then sets at 8:16 PM

Moonrise/Moonset

Astronomy >
Moonrise / Moonset Illustration

Rises at 5:05 AM with 14:20 of moolight, then sets at 7:25 PM

Castro Valley Weather Report

Western US: Diminishing heat to aid in firefighting efforts next week

July 30, 2016; 4:48 PM ET

As several large fires continue to rage across the western United States, weather conditions will gradually improve for firefighting efforts in the upcoming week. more >

Mon. Dust & Dander

Mon. Wind Maps