The Honduras Bay Islands which include the islands of Roatan, Utila, Guanaja and Cayos Cochinos, have year round weather that is really good for a vacation. While traveling in the Bay Islands you can expect day time highs in the mid 80's and 90's and night time lows in the 70's. Rainy season varies from year to year, but it normally rains from late fall through early winter which is considered the "rainy" season for Honduras. During the rest of the year, rainfall is minimal unless there's a storm in the Caribbean and often light showers during June and July.
Water temperature ranges from 78 degrees - 84 degrees with visibility consistent between 60-100ft, sometimes more! Diving takes place on both sides of island. When it is choppy on one side of island the other side is usually calm and provides the experience you hope for even in bad weather.