The hottest month in Kailua is September when the average maximum temperature is 29°, average temperature is 27° and average minimum temperature is 24°.
The coolest month in Kailua is February when the average maximum temperature is 25°, average temperature is 23° and average minimum temperature is 21°.
The longest days in Kailua are in June, with an average of 13.4 hours of daylight per day. December has the shortest days with an average of 10.8 hours of daylight per day.
The sunniest days in Kailua are in July which has the most hours of sunshine per day with an average of 7.5 hours of sunshine per day, making it a quite sunny month with some cloud cover. December has the least sunshine with an average of 5 hours of sunshine per day, making it a sunny month that is overcast at times.
The ultraviolet index is the highest in August when it reaches 13.1 and lowest in December when it reaches 6.3.
An ultraviolet index reading above 11 indicates an extreme risk of harm from unprotected sun exposure. Unprotected skin risks burning in less than 10 minutes. Take all precautions because unprotected skin and eyes can burn in minutes. Tanning will be safest before 10am and after 4pm but only with a good application of sun screen. For those with sensitive skin stay in the shade and wear protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen every 2 hours, even on cloudy days. Watch out for relections from water that may increase ultraviolet exposure.
The warmest sea water temperatures in Kailua are found in September when they peak at 27° and lowest in March when they dip to 24°.
The sea is best for swimming between May and December when the temperature is above 26° which is warm and pleasant for relaxing and swimming for long periods.
The wettest month in Kailua is March with 11.2cm of rain and the most days of rain with 21.1 days with some rain, a very wet time to visit the beach.
The driest month in Kailua is September with 2.3cm of rain and May has the fewest days of rain with 16.7 days with some rain, a wet time to visit the beach.
The most humid month in Kailua is August with a dew point (an indicator of humidity) of 22° which is very humid and quite uncomfortable for most unless you are on a beach. At night you would most likely require a fan.
The least humid month in Kailua is February with a dew point of 19° which is somewhat uncomfortable for most people in cities but fine on a beach.
The most windy month in Kailua is February when the average maximum windspeed is 23kmh and the average wind speed is 12kmh.
The least windy month in Kailua is October when the average maximum windspeed is 20kmh and the average wind speed is 11kmh.