UV Index for Castro Valley, CA

Current Castro Valley UV Index

0 (Low)

Last Updated 48 minutes ago

Hourly Castro Valley UV Index

The hourly Castro Valley, CA UV Index forecast for Saturday, October 18th, 2025.

5 Day Hourly Castro Valley UV Index Forecast

Last Updated 11 hours ago

The UV index forecast for the next five days in Castro Valley, CA has no days reaching the extreme level and no days reaching the high or very high levels. The peak UV intensity in Castro Valley over the next five days will be 4.8 on Saturday, October 18th at 1:00 pm.

The UV index forecast for Saturday, October 18th in Castro Valley, CA is below.

Time UV Index Risk
11pm 0
Low

The UV index forecast for Sunday, October 19th in Castro Valley, CA is below.

Time UV Index Risk
12am 0
Low
1am 0
Low
2am 0
Low
3am 0
Low
4am 0
Low
5am 0
Low
6am 0
Low
7am 0
Low
8am 0
Low
9am 0.5
Low
10am 1.4
Low
11am 2.8
Low
12pm 4
Moderate
1pm 4.6
Moderate
2pm 4.2
Moderate
3pm 3.2
Moderate
4pm 1.9
Low
5pm 0.7
Low
6pm 0.2
Low
7pm 0
Low
8pm 0
Low
9pm 0
Low
10pm 0
Low
11pm 0
Low

The UV index forecast for Monday, October 20th in Castro Valley, CA is below.

Time UV Index Risk
12am 0
Low
1am 0
Low
2am 0
Low
3am 0
Low
4am 0
Low
5am 0
Low
6am 0
Low
7am 0
Low
8am 0
Low
9am 0.4
Low
10am 1.3
Low
11am 2.6
Low
12pm 3.8
Moderate
1pm 4.4
Moderate
2pm 4.1
Moderate
3pm 3
Moderate
4pm 1.6
Low
5pm 0.6
Low
6pm 0.1
Low
7pm 0
Low
8pm 0
Low
9pm 0
Low
10pm 0
Low
11pm 0
Low

The UV index forecast for Tuesday, October 21st in Castro Valley, CA is below.

Time UV Index Risk
12am 0
Low
1am 0
Low
2am 0
Low
3am 0
Low
4am 0
Low
5am 0
Low
6am 0
Low
7am 0
Low
8am 0
Low
9am 0.4
Low
10am 1.3
Low
11am 2.5
Low
12pm 3.6
Moderate
1pm 4.2
Moderate
2pm 3.8
Moderate
3pm 2.8
Low
4pm 1.7
Low
5pm 0.6
Low
6pm 0.1
Low
7pm 0
Low
8pm 0
Low
9pm 0
Low
10pm 0
Low
11pm 0
Low

The UV index forecast for Wednesday, October 22nd in Castro Valley, CA is below.

Time UV Index Risk
12am 0
Low
1am 0
Low
2am 0
Low
3am 0
Low
4am 0
Low
5am 0
Low