Clothing is key in Lapland! Temperatures are an average of -10 F during the day so your only choice is to wear thermal clothes, long sleeved tops, fleece, ski jackets, jersey pants and the most important garment: a balaclava. This kind of ski mask will keep you warm while outdoors. If you are going on a safari, it is your guaranteed item for keeping you warm when you travel along the white and cold landscape.

When wind is expected to blow continuously, use a hat along with the balaclava. Wear sunglasses and if you are going snowmobiling wear googles.

Boots are key. Get insulated boots, the kind made by The North Face. Good socks and good gloves will guarantee that you enjoy the extreme temperature.  

If you hire a safari, the company will supply the gear, from the snow suit to gloves. You can also rent it yourself as there are rental stores in the main towns.

 A good place for checking out current weather, snow depth, climate statistics etc. is Finnish Meteorological Institute's website in http://www.fmi.fi/en/index.html.