Hawaii Weather. Weather in Hawaii is very consistent, with only minor changes in temperature throughout the year. There are really only 2 seasons in Hawaii: summer (called Kau in Hawaiian) from May to October and winter (Hooilo) from November to April. The average daytime summer temperature at sea level is 29.4 C while the average daytime winter temperature is 25.6º C. Temperatures at night are approximately -12º C lower.