Lastovo possesses all the basic characteristics of the Mediterranean climate, dominated by mild moist winters and warm, long and dry summers. Along with a water temperature around 27 °C in summer, the island receives around 2,700 sun hours per year ranking it among one of the sunniest in the Adriatic and pleasant for tourists. Annual rainfall is approximately 650 mm.
Since there are no permanent surface water streams, residents rely on using bores or dams and a fixed water connection to the mainland.

There are rich communities of falcon and hawk nests, which used to be exploited by the Dubrovnik Republic for falconry and traded to other kingdoms especially to Naples in the Middle Ages. The underwater life surrounding Lastovo’s waters are the richest in the entire Adriatic, featuring lobsters, crayfish, octupus and many high prized fish such as John Dory and Groupers. There are no poisonous snakes on the island.