The official temperature you see in a forecast is measured under controlled conditions: in shade, at a standard height above the ground, in a ventilated housing designed to exclude direct sunlight and precipitation. That's a useful, consistent measurement. It's just not a measurement of how you'll feel standing on a pavement in whatever the wind is doing.
What the thermometer misses
Wind alone can move the feels-like temperature several degrees below the measured air temperature. At 12°C with a 40 km/h wind, your body experiences something closer to 6°C. Humidity pushes the calculation in the other direction on hot days: 28°C at 85% humidity can feel like 35°C or more. Direct sunshine adds 4 to 8 degrees of perceived warmth that doesn't show up in the air temperature at all. And wet clothing compounds all of it by stripping away insulation exactly when you need it.
| Conditions | Air temperature | Feels-like |
|---|---|---|
| Sunny, no wind | 17°C | ~22°C |
| Overcast, no wind | 17°C | ~16°C |
| Overcast, 30 km/h wind | 17°C | ~11°C |
| Rain, 20 km/h wind | 17°C | ~10°C |
That's a 12-degree spread across four situations that all read as "17°C" in the forecast. Two people, same day, same city: one in a sunny sheltered street, one in an exposed open field at 30 km/h. They will not agree on what to wear.
Why this matters for clothing
The gap between air temperature and felt temperature is exactly the gap between "I checked the forecast" and "I dressed wrong." At 17°C on a rainy, windy day most people will want a proper jacket. At 17°C on a still, sunny afternoon many people will be comfortable in a light shirt. Treating those as the same decision because the thermometer says the same thing is where the advice breaks down.
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How KorteBroekAan.nl approaches it
The site uses the Steadman formula to combine air temperature, wind speed, humidity, and cloud cover into a single feels-like temperature. That number is what the clothing recommendation is actually based on, not the raw air temperature. It won't be perfect for every microclimate, but it's considerably closer to what you'll actually feel than the thermometer reading alone.
Each of the factors mentioned here has its own article in the Weather Explained section: wind, humidity, sunshine, cloud cover, and rain are all covered separately if you want to understand any one of them in more depth.
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 in April: is it warm enough yet?
April is unpredictable in the Netherlands. Warm spring days alternate with cold spells. We explain when shorts work in April and when they don't.