Average wind speeds in Hawaiʻi are highest during the summer when persistent trade winds blow in from the northeast at speeds of 10-25 mph. Trade winds are less prevalent in winter: wind speed exceeds 12 mph only 40% of the time. Major storms mostly occur in the winter and may yield very high winds from any direction. Occasionally, the predominant wind pattern is reversed, termed "Kona winds" for their southerly origin and can bring vog (volcanic smog) from Kīlauea over to the other islands, producing hazy conditions.