Lahaina, in Maui, was the first capital of the kingdom of Hawai’i and remained so for for more than 40 years. During this time Lahaina prospered; the whaling industry was at its height, with as many as 500 whaling ships anchored in its port. Humpback whales still migrate to Maui from Alaska and the Arctic each year to give birth, and spend the winter months from December through March or April in its warmer waters.
Whales migrate from Alaska to Hawaii every winter to mate and give birth in warmer waters, before turning back each spring and returning to the Arctic. The best times to see whales are early morning and late evenings, from about November to April or May. Calving season starts in late January, and occasionally some calves will come close to shore.
You will find good viewing along the east to north shores of Kauai. There are many on-the-water whale watching tours available, but bear in mind that it's illegal to come closer than 500 feet to a whale. However, boat tour operators often cut their engines and float in whale territory – whales will come right up to the boat to investigate.
On Maui, McGregor Point and the shallow warm waters off the west coast offer excellent vantage points for spotting humpback whales from land, so boats will not disturb the whales or pollute the water.