05/20/2026
A strong sunlight selfie to illustrate the Very High UV index today in Burlingame. But the UV Index isn’t just how sunny it is- it’s is scientific measure of how intense the sun’s ultraviolet radiation is at the Earth’s surface at a given place and time. It mainly reflects UVB rays (which cause sunburn) but also accounts for UVA exposure (which contributes to aging and skin cancer).
The scale ranges from 0–11+:
0–2 = low
3–5 = moderate
6–7 = high
8–10 = very high
11+ = extreme
At a UV Index of 8, unprotected skin can begin to burn surprisingly quickly — often within 15–25 minutes depending on skin type. For someone fair like me, the 15 minute building evacuation we had today could have been a burn waiting to happen! But I wear sunscreen every day, and sought shade right after I snapped this pic.
UV levels are influenced by:
☀️ Time of day (highest midday)
☀️ Season
☀️ Altitude
☀️ Cloud cover
☀️ Reflection from water, sand, and concrete
☀️ Ozone levels in the atmosphere
And importantly: temperature does not determine UV intensity. Cool or breezy days can still have dangerously high UV exposure.
Daily sunscreen, protective clothing, hats, sunglasses, and shade are all part of reducing cumulative UV damage over time.
UV Index forecast is high all weeks so stay ready!
