Unusually heavy rainfall, particularly in northern Finland, has already caused flooding, with more rain expected towards the end of the week.In many areas, water flows in the Iijoki River have risen to record levels for this time of year. Video: Hanna Juopperi / Risto UkkonenYle News12:38Changeable weather is expected across Finland over the coming weekend.On Friday, southern and central Finland will be mostly dry and sunny. Localised showers and thunderstorms will develop in western parts of the country during the afternoon and evening.A relatively narrow band of rain will remain around Oulu, while areas further north will stay mostly dry but largely cloudy.Heavy rainfall this week has already caused flash flooding in northern Finland. Water levels are exceptionally high for this time of year in several rivers in Northern Ostrobothnia and Lapland.According to the Finnish Meteorological Institute's 30-day weather data, it has rained almost every day this month in Oulu. Flood and rain warnings have been issued for more than 20 municipalities in Northern Ostrobothnia.Cloud cover will increase slightly on Saturday, and there will be scattered showers in some areas, but most of the country will remain dry.A strong low-pressure system is expected to move in from the south on Saturday evening and Sunday, bringing heavy rain to eastern and southeastern Finland. Winds will also strengthen considerably.Latest: paketissa on 10 artikkeliaFinland set for a damp weekendUnusually heavy rainfall, particularly in northern Finland, has already caused flooding, with more rain expected towards the end of the week.