Weather forecasts

The forecast for the village is not the forecast for the place you are going.

Norway is unusually well served here. The Meteorological Institute produces the underlying forecasts and yr.no, run jointly with the national broadcaster, is the public front end. It is free, it is good, and its data is openly available, which is why a great many apps are quietly reselling it.

The mistake everyone makes

Searching for the nearest town gives you a valley-bottom forecast. The place you are going may be a thousand metres higher, on the windward side of a ridge, and in completely different conditions. Where a mountain-specific forecast exists, use it. Where it does not, look at the forecast for the height you will be at rather than the height you will park at.

The numbers that matter

Wind, not temperature. Wind is what makes a summit unpleasant or dangerous, and it is what turns a manageable air temperature into a serious one. Ridges accelerate it well beyond the forecast for open ground.
Freezing level. This single number tells you whether precipitation arrives as rain or snow at your height, and whether wet rock will be icy rock.
Cloud base. Determines whether you get the view and, more importantly, whether you will be navigating in it.
Precipitation timing rather than total. Four hours of rain starting at noon is a different day from four hours starting at six.

The west coast problem

Moist Atlantic air hitting the coastal mountains is forced upwards, cools and dumps its water. That is why the western fjords are as wet as they are, why conditions change fast, and why a clear morning is weak evidence about the afternoon.

Winter

Avalanche warnings are published separately from the general forecast, on the national avalanche service. Any route on snow-covered steep ground in winter needs that forecast, the training to interpret it, and the equipment that goes with it. Nothing on this site covers winter mountaineering and it should not be read as though it does.

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