As with most tropical climates, seasonal rainfall follows the sun, and summer is the wettest season. There is only a  difference between the warmest month and coolest month in most of the Bahama islands. Every few decades low temperatures can fall below  for a few hours when a severe cold outbreak comes down from the North American mainland, however there has never been a frost or freeze recorded in the Bahamian Islands. Only once in recorded history has snow been seen in the air anywhere in The Bahamas, this occurred in Freeport on 19 January 1977, when snow mixed with rain was seen in the air for a short time. The Bahamas are often sunny and dry for long periods of time, and average more than 3,000 hours or 340 days of sunlight annually. Much of the natural vegetation is tropical scrub and cactus and succulents are common in landscapes.