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Mosquitoes: season and precautions
May to September.
These are general seasonal patterns for the Nordic and Baltic region, not a live forecast. Always check the current local advisory — the weather service, health authority or water-quality notice — before you head out.
The risk
Mosquitoes breed in still water and are at their fiercest around bogs, lakes and wet forest, particularly in the long northern twilight. In this region they are overwhelmingly a nuisance rather than a disease threat, but the bites itch, can become infected if scratched raw, and can turn an evening by the lake into misery. Boggy areas in high summer can produce genuinely dense swarms.
How to stay safe
Use a repellent containing DEET or icaridin on exposed skin, and cover up with long, loose sleeves at dawn and dusk. Avoid still, sheltered water at the times mosquitoes feed, and use a net over prams and over the bed when sleeping in a cabin. A fan on a terrace helps, as mosquitoes are weak fliers.
Good to know
Reactions vary a lot between people; keep an antihistamine cream to hand for those who swell up.
Other seasonal risks
Ticks (Lyme disease and TBE)
Ticks wait on grass and low vegetation in forests, meadows and gardens and attach to skin as you brush past.
Forest and wildfire risk
After a run of dry days the forest floor, heath and peat dry out and ignite easily.
Blue-green algae (cyanobacteria)
In warm, still water, cyanobacteria can multiply into a bloom that looks like spilled paint, greenish streaks or a scummy film on the surface.
Pollen and hay fever
The northern pollen season is compressed and intense.
Thin ice
Ice on lakes, rivers and the sea forms and melts unevenly.
Source: Seasonal patterns follow standard public-health and safety guidance for the region; confirm with the current local advisory. · checked 2026-09-04
Frequently asked questions
When is mosquitoes worst?
Midsummer (June–August), and always worst at dusk near water.
How do I reduce the risk from mosquitoes?
Use a repellent containing DEET or icaridin on exposed skin, and cover up with long, loose sleeves at dawn and dusk.
Enjoy the outdoors year round
TempoLife helps you keep an outdoor habit going safely through every season.