Dense fog impacts visibility and air travel in southern Finland

On Thursday morning, the Helsinki metropolitan area was enveloped in dense fog, significantly reducing visibility. According to meteorologist Laura Tuomola, visibility in southern Finland fell below 100 meters in many places, with the worst conditions recorded at Ylivieska Airport in Northern Ostrobothnia, where visibility was around 40 meters. At observation stations in Espoo and Helsinki-Vantaa, visibility was about 60 meters.

Fog is defined as visibility of less than 1,000 meters, whereas clear weather typically allows visibility to extend for kilometers. This thick fog has disrupted air traffic, causing delays for some Finnair flights at Helsinki-Vantaa due to the weather conditions.

Tuomola explains that the fog is a result of a high-pressure system located southeast of Finland combined with a very moist air mass moving in from the south. The proximity of the high-pressure center has led to weak winds, preventing the air from mixing. Morning temperatures are dropping, leading to the condensation of moisture in the air and resulting in fog formation.

According to Tuomola, this weather phenomenon is neither rare nor unusual. She notes that as autumn begins, fog is a common occurrence, especially during the fall and spring months.