| Local Time | Mon May 20 | Tue May 21 | Wed May 22 | Thu May 23 |
| UV index | 2 | 4 | 3 | 4 |
The strength of the sun's ultraviolet (UV) radiation is expressed as a Solar UV Index or Sun Index.The UV Index does not exceed 8 in the UK (8 is rare; 7 may occur on exceptional days, mostly in the two weeks around the summer solstice). Indices of 9 and 10 are common in the Mediterranean area. The Sun Index forecast refers to the daily maximum. |