Vitamin D in Massachusetts in September: sun, UV and what to expect
Too cold Too cold here in September: afternoon highs average only 21.9°C, which is too chilly for sunbathing in light clothing. Try another month or a warmer destination.
5.8 hsun window (UV 2.5+)
5.0peak UV Index
11 minto a full dose
22°Cafternoon high
6/30rainy days
23/30sunny days
The country rating is for a typical beach, but some places in Massachusetts still work in September: Boston (good).
Open Massachusetts for September on the map Find stays in Massachusetts
How long in the sun in September?
- If you travel anyway, plan your sun session around midday (roughly 11:00 to 15:00), when the UV Index peaks at about 5.0. With about a quarter of your skin bare, a full dose takes around 11 minutes for skin type III at age 30, and about 20 minutes at age 65.
- Stop well before your skin turns pink. At this UV level skin type III can start to burn after about 40 minutes of midday sun, so cover up, find shade and use SPF 30+ on skin that stays out.
- Water, sand and light surfaces reflect UV, so at the beach you get a little more sun than the number suggests, for the good and the bad.
| Skin type | Full dose, age 30 | Full dose, age 65 | Time to burn |
|---|---|---|---|
| Type I | 7 min | 13 min | 27 min |
| Type II | 9 min | 17 min | 33 min |
| Type III | 11 min | 20 min | 40 min |
| Type IV | 16 min | 30 min | 60 min |
| Type V | 21 min | 40 min | 80 min |
| Type VI | 36 min | 67 min | 2.2 h |
Minutes at midday for about 1,000 IU of vitamin D with a quarter of the body bare, at Cape Cod, the median coastal place. Time to burn is the time to reach one minimal erythemal dose and does not depend on age. A rough planning guide, not medical advice.
Places in Massachusetts in September
| Place | Rating | Sun window | Full dose | Afternoon high | Rainy days |
|---|---|---|---|---|---|
| Boston | Good | 6.2 h | 10 min | 23°C | 4/30 |
| Provincetown | Too cold | 5.9 h | 10 min | 21°C | 7/30 |
| Nantucket | Too cold | 5.9 h | 10 min | 22°C | 5/30 |
| Cape Cod | Too cold | 5.8 h | 11 min | 22°C | 6/30 |
| Martha's Vineyard | Too cold | 5.8 h | 11 min | 21°C | 5/30 |
| Plymouth | Too cold | 5.4 h | 11 min | 22°C | 5/30 |
Other months in Massachusetts
- Jan Too cold
- Feb Too cold
- Mar Too cold
- Apr Too cold
- May Too cold
- Jun Excellent
- Jul Excellent
- Aug Excellent
- Sep Too cold
- Oct Too cold
- Nov Too cold
- Dec Too cold
Best months: June to August. Full Massachusetts guide