Last updated: August 1, 2025
Understanding the UV Index in Hayward, United States, is essential for protecting your skin and ensuring your overall health. With high UV levels peaking around midday, being aware of these fluctuations helps prevent sunburn and long-term skin damage. Given Hayward's Dfb climate, where winters are cold but summers can bring intense sun exposure, knowing the UV risks is crucial. From moderate levels in the morning to extreme readings by noon, staying informed enables you to enjoy the outdoors safely while taking the necessary precautions against harmful ultraviolet rays.
As the sun rises, the UV Index begins its climb, starting at a gentle 1 at 7:00 AM. By 8:00 AM, it nudges up to 2, indicating that sun protection becomes a consideration. The intensity picks up significantly by 10:00 AM, reaching 5, before peaking at 12:00 PM with a striking 9. Notably, this peak persists through 1:00 PM to 3:00 PM, where the UVI remains steady, encouraging outdoor enthusiasts to seek shade and apply sunscreen. As the day winds down, the index gradually declines—dropping to 4 by 5:00 PM and trailing off to 1 by 7:00 PM. This hourly data not only highlights the importance of sun safety during the midday hours but also serves as a reminder to plan activities accordingly!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 3 | moderate | 30 min |
| 10:00 | 5 | moderate | 30 min |
| 11:00 | 6 | high | 25 min |
| 12:00 | 8 | very high | 15 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, the UV Index experiences notable fluctuations, influencing both visitor and resident safety. January and December boast a low UV Index of 2, allowing for extended exposure times of 45 minutes without significant risk. However, as we move into spring with February and March, the UV Index rises to 4 and 5 respectively, indicating a moderate risk with a burn time of just 30 minutes. The high-risk months arrive in April through August, with peak values of 9 and 10 during May and June, categorizing the exposure as very high and shortening safe sun exposure to as little as 15 minutes. September sees a slight decrease to a high index of 7, while October and November return to moderate levels. Visitors and residents should take precautionary measures during the higher UV months by seeking shade, wearing protective clothing, and using sunscreen regularly to minimize skin damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hayward | 2 | 4 | 5 | 7 | 9 | 10 | 9 | 8 | 7 | 5 | 3 | 2 |
| Chicago UVI | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |
| Brooklyn UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| New York City UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |