It depends on whether you will visiting Chacraseca (coastal lowlands) or La Flor (mountains). In both areas, the hottest and driest part of the year is March/April and it cools off a bit in June and July as the rainy season starts. Expect highs in the 90s and lows in the 70s and humidity above 50% for Chacraseca, and 80s/60s/>60% for La Flor. Explore the climate for Chacraseca and La Flor.