There's a big gap between drizzle and a heavy shower, and it's not just about how wet you get. It's about how fast you get wet, and what happens to your clothing's ability to keep you warm once it's soaked through.
Rainfall intensity in mm per hour
Meteorologists measure precipitation in millimetres per hour. The scale runs from barely-there drizzle to the kind of rain that makes you question your decisions.
| Rainfall (mm/h) | Description | Effect on clothing |
|---|---|---|
| Under 0.5 mm | Light drizzle | Barely gets you wet |
| 0.5-2 mm | Light rain | Slowly damp |
| 2-7 mm | Moderate rain | Wet fairly quickly |
| 7-15 mm | Heavy rain | Soaked within minutes |
| Over 15 mm | Downpour | No viable option without protection |
A half-hour walk in 1 mm/h rain is a different experience from the same walk in 10 mm/h rain, even though the duration and temperature are identical.
Why wet clothing changes the temperature equation
Clothing insulates by trapping air in its fibres. Water displaces that air, and water conducts heat roughly 25 times better than air. A soaked jacket or shirt stops being insulation and starts actively drawing heat away from your body. At 15°C you'll notice the difference fairly quickly. At 10°C, wet clothing becomes a genuine cold risk, not just an inconvenience.
This is also why rain matters more than the temperature alone suggests. A dry 12°C and a wet 12°C are not the same experience.
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How KorteBroekAan.nl uses rainfall data
Precipitation intensity appears as context in the site's weather breakdown. It doesn't override the feels-like temperature calculation directly, but it flags situations where the clothing advice needs a practical layer added: if heavy rain is forecast, a waterproof outer layer matters regardless of the temperature. The site treats it as additional information rather than a replacement for the thermal calculation.
The article on wet clothing and heat loss goes into more detail on why fabric choice matters when rain is in the forecast. The rest of the Weather Explained section covers the other factors that feed into the recommendation.
Further reading
Related articles in the Weather Explained section: