The islands experience equatorial weather with a wet and dry season. Wet season, from January through July, is when you can experience more frequent showers often with sunny spells either side of the brief but impressive showers. Dry season, from June through December, obviously has less rain but also tends to be cooler and under cloudy, but un-menacing skies.
Water temperatures in the Galapagos vary greatly depending on the time of year. Average temperatures are as follows:
January to June: 70-80°F (20-26°C)
July to December: 65-75°F (18-23°C)
However it is not unusual for the water to be as warm as 86°F (30°C) in the wet season and as low as 61°F (16°C) in dry season. We recommend you pack for both sun (lotion, sunglasses, hat, lightweight clothes) and rain (rain jacket/poncho, warm sweatshirt, waterproof sandals) as well as binoculars and insect repellent.