Water temperatures range from the low 70s F (about 22 Celsius) in January and February, to the low 80s F (about 28 C) in August and September. A full 2mm wet suit is likely to be adequate for most people. In summer, I am comfortable in a T-shirt, while my wife prefers a thermoskin. The temperature changes little with depth.

There is an overall westerly movement of water around the Hawaiian islands. This is modified locally, particularly by tidal currents. The difference between high and low tide is approximately 2 feet (0.6m). Tidal currents can sometimes move faster than people can swim, so it is a good idea to consult tide tables before diving. The local newspapers, such as West Hawaii Today, publish the times of high and low tide.

If you are planning on doing a lot of shore diving, it is also worth noting that in winter, it is quite common to have long periods of high surf, particularly on the north and west shores, which make shore diving entries and exits more difficult, and sometimes impossible. This is more true for the Big Island than the other Hawaiian islands because it has more rocky entries than the other islands, due to its relative geological youth.

Check here for Glenn James' weather report and sea conditions for divers, for all islands. When you are in the islands, his 7.45 a.m. weather programme, which is broadcast on the public broadcasting channel, is well worth watching.

Telephone for 24-hour forecast: 961-5582

Average Temperatures

(Taken from 'Exploring Tropical Isles and Seas' by Frederic Martini)

 Air Temp
C (F)
Sea Temp
C (F)
Wind
Dir
Swell
Dir
Jan 21.7 (71) 22.8 (73) NE NE
Feb 21.7 (71) 22.8 (73) NE NE
Mar 22.2 (72) 23.3 (73.9) ENE NE
Apr 22.8 (73) 24 (75.2) ENE NE
May 23.9 (75) 25.2 (77.4) ENE -
Jun 25 (77) 26.4 (79.5) ENE -
Jul 25.6 (78) 26.4 (79.5) E SW
Aug 25.6 (78) 26.8 (80.2) E SW
Sep 25.6 (78) 26.7 (80.1) ENE -
Oct 25 (77) 26.3 (79.3) ENE -
Nov 23.9 (75) 24.9 (76.8) ENE -
Dec 22.8 (73) 23.2 (73.8) ENE NE