Many webpages inform about the up-to-date weather and other related topics:

Weather Forecast:

The Videotext of the Swedish Television is available in the Internet:
Väderinformation

The Swedish Institure for Space Science also cares for the weather on earth, and they make measurements in Kiruna:
Data from Kiruna

The fastest way to get a three-day weather prediction ist CNN:

Gällivare	Jokkmokk	Kiruna	Kvikkjokk
Nikkaluokta	Ritsem	Östersund	Stockholm

Up-to-date Pictures:

The view on northern Sweden from a satellite orbit near the equator is not so good. The following page shows the clouds and is fairly well up-to-date:
Scandinavia on Wetter Online
Click on one of the dates and you will get a detailed picture.

A closer look is provided by web-cameras, and you can view the midnght sun or the darkness of winter:
Webcamera in Tromsö/Norwegen

Other Informations

Near Abisko Turiststation at the northern end of Kungsleden is Abisko Research Station, and their meteorological observations are available in the Internet.

The Geophysical Institute in Sodankylä/Finland shows pictures of northern lights.