Castro Valley, California, United States UV Index Forecast

Find the UV Index forecast for today, tomorrow and the next 15 days for Castro Valley, California, United States, The Ultraviolet Index forecast, which measures the radiation from the sun that reaches the Earth's surface is updated hourly.

NOW
12:25 am

Low0

UV INDEX

Hourly UV Index Forecast for Today
October 31, 2025

0
8 am
1
9 am
3
10 am
4
11 am
6
12 pm
6
1 pm
6
2 pm
5
3 pm
4
4 pm
3
5 pm
  • Low
    1-2
  • Moderate
    3-4-5
  • High
    6-7
  • Very High
    8-9-10
  • Xtreme
    11+

As of 12:25 am today in Castro Valley, California, United States, the UV Index is currently at a Low level of 0.

Summary of Hourly UV Index Forecast for Today and Tomorrow in Castro Valley, California, United States.

Today

Time Range UV Index Risk
8 am 0
Low
9 am 1
Low
10 am 3
Moderate
11 am 4
Moderate
12 pm 6
High
1 pm 6
High
2 pm 6
High
3 pm 5
Moderate
4 pm 4
Moderate
5 pm 3
Moderate

Tomorrow

Time Range UV Index Risk
8 am 0
Low
9 am 1
Low
10 am 2
Low
11 am 4
Moderate
12 pm 4
Moderate
1 pm 5
Moderate
2 pm 5
Moderate
3 pm 4
Moderate
4 pm 3
Moderate
5 pm 3
Moderate

Daily Castro Valley UV Index Forecast for the next 15 days:

6
31 Oct
5
1 Nov
6
2 Nov
6
3 Nov
6
4 Nov
6
5 Nov
5
6 Nov
6
7 Nov
6
8 Nov
5
9 Nov
6
10 Nov
6
11 Nov
6
12 Nov
5
13 Nov
  • Low
    1-2
  • Moderate
    3-4-5
  • High
    6-7
  • Very High
    8-9-10
  • Xtreme
    11+

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