As mentioned already, April is not really winter anymore, not even up here in the North.
The more North you head, the more natural light you will have. Go close or above the Arctic Circle and the sun doesn't set at all in June-July. It's an experience in itself. If you're coming this way and camping, consider a dark coloured tent, I've heard tourists complain it can be difficult to sleep due to all that light. We tend to have mosqitoes up here, but how much in any given year is anyone's guess. Again, if you're camping, any tent of reasonable quality is really easy to keep bug-free, far easier than a camp site rental cabin for example. We don't have much other wildlife to be concerned about, bears and wolves in Finland are extremely shy. Ticks are common in the Finnish archipelago area and along the coast and some percentage of them carry either borreliosis or the Lyme disease virus. You should take precautions. Ticks are also found in several Eastern EU member states.
Recommended bike touring regions in Finland include the
Aland islands and the
Turku Archipelago Trail next to them. Not a lot of mileage (the Trail especially consists of small islands with interconnecting ferries) but stunning scenery combined with low colume and considerate traffic makes for enjoyable riding. Another favorite area for me in terms of scenery is the
Saimaa Lake Region. Longer distances, hilly routes, small gravel roads if you're so inclined. If it's more city sights you're after, Helsinki and Porvoo regions have something to offer there, as well as Turku.
If needed, cycling and public transportation are easily combined in Finland. Buses, ferries and trains all take bikes for a small fee. With trains and longer distance ferries advance booking is advisable. This by the way varies a lot depending on which European country you find yourself in, so it's a good idea to check in advance. For example, in our neighbouring Sweden you are requested to pack and send your bike(s) as cargo in most all trains and buses.
--J