The temperature in Oahu during March typically hovers around 76 degrees. The island receives more rain in the winter months, but hurricanes are not a concern. Overall, winter in Oahu is a popular time of year to visit due to its beautiful weather conditions.

Box jellyfish, which are found in Hawaii, tend to populate the waters around the island for about 9 to 10 days following a full moon. Sharks are present in all ocean waters, so the best policy is to always approach the ocean as a wilderness area. Swimming with a lifeguard present can minimize potential encounters with wildlife. Do not hesitate to ask lifeguards about the present conditions of the water.

March is a time of year you might see humpback whales, blue whales, and pygmy whales. Additionally, you are likely to spot dolphins, manta rays, and monk seals. Winter months are a migratory season in the waters around Hawaii. There is much to see.

I hope this helps in your travel planning. Have a wonderful trip!