The unique geography of the Kuril Islands determines the islands' climatic conditions. The islands stretch in latitude from a temperate climate near Japan, producing spruce and larch forests to subarctic and arctic climates of Kamchatka, with tundra vegetation. In winters, which last from November until March, one can expect high winds, heavy snow, and frequent storms that draw cold continental air across the Sea of Okhotsk from Northern China and Siberia. About 30–40 inches (760–1,000 mm) of precipitation fall on the islands, most of it as snow. Summers are characterized by dense fog, mild southerly winds and fewer storms than in winter.

In most places in the northern hemisphere, northern areas tend to have more ice accumulation than southern areas. But this is not the case in the Kuril Islands. Counter-intuitively, sea ice concentrations in the Kurils tend to be highest in the southern portion of the island chain. This is because sea ice produced in the northern Sea of Okhotsk circulates counter-clockwise in ocean currents, and accumulates in late spring around Kunashir and Iturup, and occasionally Urup, as well.