The Dutch talk about the weather constantly, and check Buienradar like a national reflex, because in a flat, windy, low country it genuinely matters (especially when you cycle everywhere). When a code geel, oranje or rood flashes up, here is what it actually means, and the vocabulary to read any warning. The colour codes are not a Dutch quirk: the KNMI feeds the pan-European Meteoalarm network, so the same geel, oranje and rood carry the same meaning on a drive across the border.
The colour codes
Weather warnings come from the KNMI (the national weather institute) in four colours, as the KNMI explains its warnings:
| Code | Meaning |
|---|---|
| groen | nothing to warn about |
| geel | be alert: chance of dangerous weather |
| oranje | high chance of dangerous/extreme weather; possible damage, injury or disruption |
| rood | weeralarm: extreme weather, big impact on society |
So geel is “keep an eye out,” oranje is “this is likely serious,” and rood is “extreme, act accordingly.”
How far ahead they come, and what changed in 2026
Two things about Dutch warnings changed on 20 May 2026, and most guides on the web (including an earlier version of this one) still describe the old system. Per the KNMI’s own explanation of the renewed warnings:
- They are no longer issued per province. A warning is now drawn around a smaller area wherever the forecast allows it. Under the old system a storm clipping one corner of a province put the whole province on code oranje; now the warning can cover just the part that is actually affected. The KNMI has been rolling this out through 2026.
- All three colours can come up to 48 hours ahead. That is the legal maximum. It used to be that geel arrived two days out while oranje and rood appeared much closer in, so a late rood was the frightening one. The colour no longer tells you how soon it will hit. Possible dangerous weather is flagged up to seven days ahead in the KNMI’s forecast table without a colour attached, as a heads-up rather than a warning.
In practice: read the area and the time window on the warning, not just the colour, because code oranje no longer implies “within a day” or “the whole province”. Warnings now also describe the expected consequences and what to do, not only what the weather will be.
One addition is worth turning on if you cycle. Since the summer of 2026 the KNMI app has a beta feature, cellwarn, that alerts you when a severe thunderstorm will reach your location within 15 minutes. That is a different thing from a regional colour code, and far more useful on a bike.
The weather vocabulary
Warnings are issued for specific phenomena, per the KNMI warnings dossier:
| Dutch | English |
|---|---|
| windstoten | wind gusts |
| gladheid | icy/slippery conditions |
| sneeuw | snow |
| onweer | thunderstorm |
| hitte | heat |
| zicht | (poor) visibility |
| weeralarm | weather alarm (code rood) |
| neerslag | precipitation |
Where to look: the KNMI site and Buienradar (with its famous regenradar, rain radar).
Heat: the hittegolf and the Nationaal Hitteplan
Heat warnings use the same colours, plus two terms of their own. A hittegolf (heatwave) has a strict definition, set by the KNMI: at least five consecutive summer days with a maximum of 25 degrees or higher measured at De Bilt, of which at least three are tropische dagen with a maximum of 30 or higher. Because it is measured at that one station, the whole country can officially be in a heatwave while your town is cooler. For dangerous heat the KNMI issues code geel, oranje or rood like any other warning; code rood for heat is the top level and a health warning, not weather trivia.
Separately, the RIVM can activate the Nationaal Hitteplan, the national heat plan, which is independent of the heatwave definition: it can switch on because of expected night temperatures and humidity, not only daytime highs, and it mobilises care for the people heat actually threatens, the elderly and the chronically ill, as the Red Cross stresses every summer. When it is active the advice is practical: drink voldoende (drink enough), stay in the shade and cool, and check on elderly neighbours and relatives.
| Dutch | English |
|---|---|
| de hittegolf | heatwave (5+ days of 25+, 3 of them 30+) |
| de tropische dag | a day with a maximum of 30 or higher |
| het Nationaal Hitteplan | the national heat plan |
| drink voldoende | drink enough |
Where it connects
Weather is the national small-talk topic, so these words earn their keep in ordinary conversation as well as on a bike: the everyday phrase set. The other alert that will startle you is NL-Alert, the national emergency broadcast, and a code oranje morning is exactly when the school run gets interesting.
The bottom line
Dutch weather warnings are the KNMI’s colour codes: groen (nothing), geel (be alert), oranje (likely dangerous, possible damage), and rood (a weeralarm for extreme weather). Since 20 May 2026 they are drawn around a local area rather than a whole province, and all three colours can be issued up to 48 hours ahead, so read the area and the time window and not only the colour. Watch them on the KNMI site and Buienradar, and learn the words, windstoten, gladheid, onweer, hitte, and you’ll know whether a warning means “grab a coat” or “do not get on that bike.”
Frequently asked questions
What do the Dutch weather codes geel, oranje and rood mean?
They are the KNMI’s warning levels. Code groen: nothing to warn about. Code geel: be alert, there is a chance of dangerous weather. Code oranje: a high chance of dangerous or extreme weather, with possible damage, injury or major disruption. Code rood: a weeralarm (weather alarm) for extreme weather with a big impact on society. Each step up means more certainty and more severity.
How far in advance are KNMI weather warnings issued?
Up to 48 hours, for all three colours. Since 20 May 2026 the colour no longer tells you how close the weather is: code geel, oranje and rood can each be issued up to two days ahead, which is the legal maximum. Possible dangerous weather appears up to seven days out in the KNMI’s forecast table without a colour attached. Warnings are also no longer issued per province, but for a smaller area wherever the forecast allows it.
Where do I check Dutch weather warnings?
On the KNMI (the national weather institute) website and on Buienradar, the hugely popular Dutch weather app/site, which shows current warnings alongside its famous rain radar. Warnings cover wind (windstoten), rain (regen), ice/snow (gladheid, sneeuw), thunderstorms (onweer), heat (hitte) and poor visibility (zicht). Checking before you travel, especially by bike, is a very Dutch habit worth adopting.
What counts as a heatwave in the Netherlands?
At least five consecutive days with a maximum of 25 degrees or higher, measured at De Bilt, of which at least three reach 30 or higher (tropische dagen). It is a formal KNMI definition, so the country can be in an official heatwave while your own town is cooler. Dangerous heat also gets a colour code, and the RIVM can activate the Nationaal Hitteplan separately to protect vulnerable people.
What does code oranje mean on Buienradar?
A high chance of dangerous or extreme weather in your province within about 24 hours, with possible damage, injury or disruption. It is issued when the probability is roughly 60% or more. Check before you drive or cycle, expect transport disruption, and for wind or ice consider not going out at all. Code rood is the next level up and means extreme weather with major impact.