Dimma watches MET Norway’s fog forecast for up to five places. When fog looks likely between 08 and 15, it sends you a notification around 18:30 the evening before, so you can be out with the camera when it comes.
Add a place below to start. You see each place’s forecast hour by hour, next to what the nearest weather station measures.
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Past alerts
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Notifications
On iPhone: notifications only work once Dimma is on your Home Screen.
- Tap the Share button in Safari
- Choose Add to Home Screen
- Open Dimma from the icon
- Turn on notifications here
Questions
Where does Dimma work?
Anywhere. In the Nordics, MET Norway uses a detailed regional forecast. Elsewhere it uses a coarser global one, so fog in valleys and over small lakes is easier to miss.
When do alerts arrive?
Around 18:30 local time at the place, the evening before a fog chance of 60% or more between 08 and 15.
Where does “Seen at” come from?
In Sweden, the nearest SMHI weather station within 50 km. Elsewhere, or where SMHI has none that close, the nearest airport weather report within 50 km, from aviationweather.gov. Airports are few in the countryside, and fog is local, so a station a few kilometres away can see something different: take it as a hint, not proof.
What do “fog seen” and “no fog seen” mean?
Once an alert’s day is over, Dimma looks at what the same station measured between 08 and 15. If visibility dropped below 1 km, that is “fog seen”. Nothing is shown when no station is near or it measured nothing.
Does Dimma count visits?
Yes, with GoatCounter: which page, the site you came from, browser, screen size and country. No cookies, and nothing that tells who you are. Your places stay on your phone, and on Dimma’s server only if you turn on notifications. Each evening Dimma also keeps the forecast and what the nearest airport measured for each place, rounded to about 1 km and without names or devices, to make the fog rules better. The visit counts are public.