Does Hayes Valley need sun protection in winter?

Not every day. Midwinter middays in Hayes Valley often sit below UV 3, but clear late-winter and early-spring days cross the threshold before summer fully arrives. Check the live index.

Can you burn on a cool day in Hayes Valley?

Yes. UV is not heat. A cool, windy or lightly cloudy day in Hayes Valley can still sit at UV 3 or above, especially from spring through autumn. Temperature on this page is for context only; the UV number is what decides protection.

UV index in Hayes Valley today

Hayes Valley in California sits inland at 37.8°S, where dry air and fewer clouds often mean harsher UV than the temperature suggests. Summer middays typically reach 9–11 (very high to extreme). This is cool-temperate America: summer UV still climbs into the very high band, and spring arrives before the weather feels hot.

Live reading · data by Open-Meteo · reference monitoring by ARPANSA

Today and tomorrow in Hayes Valley

Peak UV, temperature and conditions for Hayes Valley. Tomorrow’s peak is the number to plan around if you’re heading out in the middle of the day.

Weather conditions right now

Cloud and rain cut heat more than they cut UV. A partly cloudy day in Hayes Valley can still sit at protection levels. Why you burn on cloudy days.

When Hayes Valley needs sun protection

Sun protection is needed in Hayes Valley typically from May through September, and any clear spring or fall day UV reaches 3. Inland heat or a cool change does not change the UV index; go by the number, not how the day feels.

The threshold, per SunSmart and ARPANSA: whenever UV reaches 3 or above, Slip on covering clothing, Slop on SPF 50+ sunscreen, Slap on a hat, Seek shade and Slide on sunglasses. Read the full sun safety guide.

The UV scale at a glance

0–2Low
3–5Moderate
6–7High
8–10Very high
11+Extreme

Frequently asked questions

When does Hayes Valley need sun protection?: Whenever the UV index is 3 or above. In Hayes Valley that is typically from May through September, and any clear spring or fall day UV reaches 3. The EPA Sun Safety action steps apply at the same threshold used worldwide.
Does Hayes Valley need sun protection in winter?: Not every day. Midwinter middays in Hayes Valley often sit below UV 3, but clear late-winter and early-spring days cross the threshold before summer fully arrives. Check the live index.
Can you burn on a cool day in Hayes Valley?: Yes. UV is not heat. A cool, windy or lightly cloudy day in Hayes Valley can still sit at UV 3 or above, especially from spring through autumn. Temperature on this page is for context only; the UV number is what decides protection.