The weather depends on what part of the country you are in. The west coast is rainy. The rain doesn't come down, it comes horizontally, so an umbrella is not helpful, but GOOD QUALITY rain pants and jacket are pretty important. The east and south coasts have more temperate weather, with less snow and rain and warmer summers (65-75 degrees). Inland cities and northern Norway get a lot of snow and it is much colder. In the North, you experience 2-3 hours of daylight in the winter and 2-3 hour of night in the summer. The climates are comparative to Seattle, San Francisco, and Alaska, depending on what part of the country you are in.
There are some excellent winter coats available in Norway, but most everything is way more expensive there. You can find good, quality items in the U.S. for way cheaper, just make sure they have a good cold weather rating.
They do not sell common over-the-counter medicines like ibuprofen or cold medicine there without a prescription, so consider bringing a small supply with you.
All toiletries and many brands Americans are familiar with are available there.
Bring good, quality winter gear. Coat, wool socks, scarf, gloves, hat, and boots. Blundstone winter lined boots are awesome boots to have there. Dressing in layers will keep you warmer. Also good quality comfortable shoes for the other seasons.
A good guide for Elders is to bring about 1/2 short sleeved shirts, and 1/2 long sleeved shirts. You only need 1 suit. They only wear them to Church and conferences.
It is a challenging mission as far as language and teaching. People there are not super warm and friendly, so be prepared for that.
Missionaries are often on bikes or use public transportation.
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