Oulu, where it's located

The climate of Oulu is cold continental, with freezing winters and mild summers.
The city is located in north-central Finland, in the northernmost part of the Gulf of Bothnia (called Perämeri), which can freeze in winter. We are at the 65th parallel, therefore south of the Polar Circle. The white nights, when the sun sets but it's not completely dark even at midnight, occur from April 25th to August 18th.
The average temperature of the coldest month (January) is of -9.8 °C (14 °F), that of the warmest month (July) is of 16.6 °C (62 °F). The lowest record is -41.5 °C (-42.7 °F), the highest is 33.2 °C (92 °F). Here are the average temperatures.
Oulu - Average temperatures
Min (°C)-14-13-9-339121051-6-11
Max (°C)-6-6-16121821181260-4
Min (°F)7916273748545041342112
Max (°F)212130435464706454433225

Precipitation amounts to 475 millimeters (18.7 inches) per year: it is therefore quite scarce. It ranges from 20 mm (0.8 in) in the driest month (April) to 70 mm (2.8 in) in the wettest (July). Here is the average precipitation.
Oulu - Average precipitation

On average, there are around 1,740 sunshine hours per year. In summer, also due to the length of the days, the sunshine amount is quite good, and definitely better than in Norway. Here are the average sunshine hours per day.
Oulu - Sunshine

The sea temperature ranges between -1 °C (30 °F) and 14 °C (57 °F). So, it is cold all year round. It is useful to recall that sea water freezes at about -2 °C (28.5 °F). Here are the average sea temperatures.
Oulu - Sea temperature
Temp (°C)10-1027121412853
Temp (°F)343230323645545754464137


Best Time

The best time to visit Oulu is the summer, from June to August, since it is the mildest season. However, you must take into account some rainy days and a bit of cold at night.