Two days in a row, both sitting at 14°C. On the cloudy one you reach for a jacket without thinking. On the sunny one a light shirt feels fine, maybe even warm by midday. The thermometer hasn't changed. What has changed is whether the sun is actually reaching you.
Why sunlight adds warmth the thermometer doesn't capture
The sun emits infrared radiation that passes straight through the air and gets absorbed directly by your skin. Air temperature barely shifts as a result, but your body picks up the energy immediately. On a still, sunny day that can add 3 to 8 degrees of perceived warmth, and in summer the effect can reach 10 degrees.
How much you gain depends on a few things. The angle of the sun matters a lot: high in summer, low in winter. Clouds block direct radiation almost entirely when the sky is fully overcast. Wind can strip away the warmth the sun just added, which is why a breezy sunny day and a calm cloudy day can end up feeling remarkably similar even though they look completely different.
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How KorteBroekAan.nl accounts for sunshine
The site factors cloud cover into its feels-like temperature calculation. On a clear day the threshold for recommending shorts gets reached at a lower air temperature than on a grey one. A 14°C sunny forecast might tip the advice toward lighter clothing; the same 14°C under thick cloud probably won't.
The practical gap is real. A sunny 14°C day can feel like 19°C. The same 14°C overcast with a bit of wind can feel closer to 10°C or 11°C. If you've ever been surprised by how warm a spring morning felt despite the forecast looking modest, or how grey and chilly a day seemed despite the number on the app, this is why.
Sunshine is only part of the picture. The other articles in the Weather Explained section cover how wind, cloud cover, humidity, and rainfall all feed into what you'll actually feel outside.
Further reading
Related articles in the Weather Explained section:
Read next
Why cloud cover matters for clothing advice
The same thermometer reading feels completely different under a clear sky versus a grey one. Cloud cover changes how much solar radiation actually reaches you.
Why feels-like temperature matters for clothing advice
The thermometer reads 18°C but you still feel cold. How is that possible? We explain what feels-like temperature is, how it is calculated, and why KorteBroekAan.nl uses it.
Why humidity matters for clothing advice
Humidity works in both directions: it makes hot days feel suffocating and cold days feel more biting. Here's what's actually happening and why KorteBroekAan.nl includes it.
Why rain probability matters for clothing advice
A 60% chance of rain doesn't mean it will rain 60% of the time. Here's what rain probability actually tells you and when it should change what you wear.
Shorts on the terrace: sun changes everything
A terrace in the sun feels warmer than the thermometer suggests. Direct radiation can add several degrees to how warm your legs feel — but shade and wind take it away fast.