On average, Moscow has 1731 hours of sunshine per year, varying from a low of 8% in December to 52% from May to August. This large annual variation is due to convective cloud formation. In the winter, moist air from the Atlantic condenses in the cold continental interior, resulting in very overcast conditions. However, this same continental influence results in considerably sunnier summers than oceanic cities of similar latitude such as Edinburgh. Between 2004 and 2010, the average was between 1800 and 2000 hours with a tendency to more sunshine in summer months, up to a record 411 hours in July 2014, 79% of possible sunshine. December 2017 was the darkest month in Moscow since records began, with only six minutes of sunlight.