The average daytime summer temperature at sea level is 85° F (29.4° C), while the average daytime winter temperature is 78° (25.6° C). Temperatures at night are approximately 10° F lower than the daytime.
Are Hawaii beaches warm in winter?
Even though January is one of Hawaii's cooler months, the ocean temperatures are still warm enough to allow you to swim comfortably. You can expect the ocean temperatures to reach around 72 to 76 degrees F, making the water just slightly cooler than the outside temperatures at the peak of the day.
Is January too cold for Hawaii?
If you're planning a Hawaii vacation to enjoy hot, sunny weather, rest assured—January is still plenty hot for a beach vacation. The average high temperature is around 79 to 80 degrees F in January, while the average low temperature is approximately 65 degrees.