The Caribbean's shoulder season is in late spring and fall when the weather is milder in the north. The weather in the Caribbean is warm with little rainfall, but the islands are less busy than in winter months. You can expect temperatures with average lows in the mid-70s to average highs in the mid-80s.ourism booms from mid-December through mid-April. The winter weather in the Caribbean features little rainfall and has average lows in the low 70s and average highs in the mid-80s. Northern Caribbean destinations' lows are closer to the 60s, while southern islands' lows are in the 70s.