Why 20 degrees is not always shorts weather

20°C has a reputation. It's the number people point to as the turn-of-the-season threshold, the temperature at which summer clothing becomes reasonable. And on a still, sunny, dry day it holds up: 20°C under a clear sky can feel like 25°C, and shorts are a perfectly sensible choice.

Add wind, and the story changes. A 40 km/h wind at 20°C brings the feels-like temperature down to around 14°C. That's not shorts weather for most people. Add overcast skies on top of that and you're looking at 11 to 12°C felt temperature.

The conditions that determine whether 20°C is actually comfortable

The bottom of that table is the same thermometer reading as the top, and yet the reasonable clothing choices are completely different. This is why "it said 20°C" is not always a satisfying answer when someone asks why you're cold.

The threshold question

KorteBroekAan.nl recommends shorts when the feels-like temperature reaches 15°C. On a still, sunny 20°C day that threshold is comfortably exceeded. On a windy, overcast 20°C day it may not be, or it may be a marginal call. The threshold is also adjustable: the Weakling to Legend slider lets you set your own temperature comfort range, which shifts where the recommendation lands.

The point isn't that 20°C is bad or misleading as a number. It's that the number alone is insufficient. Two days at 20°C can feel like two different seasons depending on what's happening in the air around that temperature.

If 15°C seems like a more interesting puzzle, that article is here. The full breakdown of what goes into the feels-like calculation is across the Weather Explained section.

Further reading

Related articles in the Weather Explained section:

• 15°C: warm or cold?
• Why feels-like temperature matters
• Why wind matters for clothing
• Why temperature alone is not enough