UV index map Belgium

The UV season in Belgium

Belgium lies between about 49.5 and 51.5 degrees north. UV is strongest from May to August, peaking around the June solstice; the often cloudy sky keeps many days in the low or moderate range, but on clear summer days the index can reach the high band around midday, especially on the coast, where wind and sea breeze hide the strength of the sun. In the Ardennes and the High Fens (Signal de Botrange, 694 m) altitude adds a little. From November to February the index is mostly low. The RMI publishes the official forecasts and warnings; this site adds the daily UV maximum for each place.

How to read the index

The UV index uses the scale of the World Health Organization: 1 to 2 is low, 3 to 5 moderate, 6 to 7 high, 8 to 10 very high and 11 or more extreme. Health agencies advise sun protection whenever the index reaches 3 or more. The number on this map is the forecast maximum for the day, reached around solar noon, and it takes the forecast cloud into account. Because it is a peak value, UV is lower early in the morning and late in the afternoon, but a day with an index of 6 still has hours above 3.

Sunscreen, SPF and timing

Use a broad-spectrum, water-resistant sunscreen of SPF 30 or higher, apply it about 20 minutes before going out, and reapply every two hours and after swimming or heavy sweating. Sunscreen works best together with a hat, sunglasses, clothing that covers the shoulders and shade in the middle of the day. Skin type matters: fair skin burns first, but UV damages every skin type, and children need extra care.

Altitude, cloud, snow and water

UV rises by roughly 10 % for every 1,000 m of altitude, so a mountain path gets more than the valley on the same day. Fresh snow reflects up to about 80 % of UV, and water and sand reflect a smaller share, so a day on the snow or the beach is stronger than the number alone suggests. Thin or broken cloud lets much of the UV through, and gaps between clouds can briefly raise it, so a bright, cloudy day can still burn.

Where the figures come from

The UV index comes from the Open-Meteo forecast for the exact coordinates of each place, updated several times a day. It is a model value, not a measurement; the method is described on the methodology page. The index is general information, not medical advice: for a personal assessment, ask a doctor or a pharmacist.