Live UV forecast for 1,300 cities
Japan stretches from 24.3448° to 45.4094° latitude (Northern hemisphere), so UV conditions differ a lot from region to region. The clear-sky UV index reaches ≈ 8.9 in Hirara (peak in June), while in Wakkanai the yearly maximum is only ≈ 7.7.
| Zone | Cities | J | F | M | A | M | J | J | A | S | O | N | D | Peak |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Subtropical | 494 | 4.1 | 5.1 | 6.4 | 7.5 | 8.1 | 8.3 | 8.2 | 7.8 | 7.1 | 5.9 | 4.8 | 4 | 8.3 |
| Temperate | 806 | 3.6 | 4.7 | 6 | 7.2 | 7.9 | 8.2 | 8.1 | 7.6 | 6.8 | 5.5 | 4.4 | 3.5 | 8.2 |
Calculated clear-sky noon peaks at the average latitude of each zone. Real values vary with clouds, altitude and ozone.
Using Tokyo as a reference: the UV index reaches 6+ in March, April, May, June, July, August and September. In the sunniest zones (see table) SPF 30–50+ is needed almost year-round; in the mildest — only in late spring and summer.
The calculated clear-sky maximum is ≈ 8.9 — in Hirara around June. Values above this occur only near the equator and in high mountains.
Hirara (peak ≈ 8.9), followed by Ishigaki and Miyakojima. The mildest sun is in Wakkanai (max ≈ 7.7).
In Tokyo and similar latitudes the UV reaches 6+ in March, April, May, June, July, August and September: use SPF 30–50+ on sunny days. Protection is advised from UV 3.
No — the local maximum is ≈ 8.9. UV 11+ occurs only near the equator, in deserts and high mountains.