Located between 11 and 15 degrees north latitude, Nicaragua [1]'s tropical climate ranges from 27–32°C (81–90°F) during the rainy season, and 30–35°C (86–95°F) in the dry season, but varies remarkably by region: In the mountains of Matagalpa and Jinotega, the temperature can be 10°C cooler, while in León [2] and Matagalpa, they can be 10°C warmer, making ordinary travelers feel like glazed chickens roasting over the coals.
Nicaragua’s invierno (winter, or rainy season) lasts approximately May–October, and verano (summer, or dry season) lasts November–April: rain during these months may mean just a quick shower each afternoon, or a deluge that goes on for days.
As you travel east toward the Atlantic coast or down the Río San Juan [3], the rainy season grows longer and wetter until the dry season only lasts the month of April.
Links:
[1] http://www.moon.com/destinations/nicaragua
[2] http://www.moon.com/destinations/nicaragua/northwest-coast/leon
[3] http://www.moon.com/destinations/nicaragua/rio-san-juan/down-the-rio-san-juan