February is the coldest month of the year in Hawaii with the average temperatures in a steady 68°F (20°C) to 79°F (26.1°C) range. Cold fronts are common and precede a cold wave from the northern Polar Regions - however, the considerable distance that any air mass has to travel to reach the islands reduces its intensity so that temperatures are never extreme. Instead, localized weather patterns matter more, as the temperatures register a freezing 27°F (-2.8°C) to 43°F (6.1°C) in the mountains to a steady range of 66°F (18.9°C) to 81°F (27.2°C) in the leeward areas at sea level. Average sea temperatures are at a warm 74°F (23.3°C), and it is fit for swimming, sailing, snorkeling, and other water activities that are rarely possible elsewhere in the United States during the winter. Keep an eye on the weather for thunderstorms, as they are common in February. Volcanic fog is a phenomenon to be aware of while exploring the active volcanoes of Hawaii!