Can you get sunburnt on a cloudy day?
By the Sunloop UV team. Reviewed against Cancer Council and ARPANSA guidance on .
The short answer
Yes. Thin or broken cloud lets most UV through, and the edges of some clouds can even bounce extra UV towards the ground. Thick, dark cloud blocks more, but it rarely lasts all day. On a cloudy day, check the UV index rather than the sky.
Why cloud doesn’t stop UV
Cloud blocks the sun’s warmth and glare far better than it blocks UV. The World Health Organization notes that up to 80% of UV can pass through light cloud. You feel cooler, so you stay out longer, and that’s how many people end up burnt on an overcast day.
Broken cloud can be worse than a clear sky for short spells. Sunlight scatters off the bright edges of clouds, and for a few minutes the UV reaching you can rise above the clear-sky level.
When cloud does help
Thick, dark, low cloud, the kind that brings steady rain, cuts UV a lot. The catch is that it rarely sits overhead from morning to evening. A gap of an hour around midday can deliver most of the day’s UV.
What to do
Check the UV index for your suburb. Forecasts already account for expected cloud, so if it says 6, plan for 6. If the forecast is for patchy cloud, assume the higher end of the day’s numbers when you’re outside around the middle of the day.
Haze and smoke
Bushfire smoke and dust reduce UV a little, but not reliably. Treat a hazy day like a cloudy one and go by the index.
Check when you need sunscreen today
Sources
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General information only, not medical advice. If you’re worried about a spot, a mole or a bad burn, see your GP or a dermatologist.