UV index in Philadelphia in April
In April, the UV index in Philadelphia typically peaks around 5.2 at midday — moderate on the WHO scale — with individual days reaching 7.2 in recent years. Sun protection is needed around the middle of the day.
How fast would you burn?
Estimated time to sunburn in unprotected midday sun at UV 5.2:
| Skin type | Time to burn |
|---|---|
| I — Very fair | ~26 min |
| II — Fair | ~32 min |
| III — Medium | ~45 min |
| IV — Olive | ~58 min |
Estimates from typical minimal erythemal doses — see methodology. Darker types (V–VI) burn slower still. Reflection off water or sand shortens all of these.
What to do about it
- Pack SPF 30+ and use it for extended midday time outside — fair skin can burn in under an hour at these levels.
- Mornings and late afternoons are generally low-risk without protection.
- Sunglasses are worth it: cumulative UV drives cataracts even at moderate levels.
Planning a trip? Check the live UV index in Philadelphia closer to your dates — day-to-day cloud cover moves the real number around this average.
Philadelphia's UV year at a glance
| Month | Typical midday peak | Level |
|---|---|---|
| January | 2.4 | Low |
| February | 3.3 | Moderate |
| March | 4.6 | Moderate |
| April | 5.2 | Moderate |
| May | 5.6 | Moderate |
| June | 6.9 | High |
| July | 7 | High |
| August | 6.3 | High |
| September | 5 | Moderate |
| October | 4.1 | Moderate |
| November | 2.8 | Low |
| December | 2.1 | Low |
The strongest month is July (typical peak 7); the gentlest is December (typical peak 2.1).
← March · Philadelphia live · May →
☀️ Get tomorrow's UV before it gets you
One short email each morning with your city's peak UV, when it hits, and whether you need sunscreen that day. Free, no spam, unsubscribe anytime.