How's the weather in Managua? In a word, hot! Well, not always scorching, but usually it is at least warm if not torrid. The average temperature in Managua, according to Weather Underground, is 82 degrees Fahrenheit or 28 degree Celsius.
The main differential in temperatures in the tropics is always elevation. In this instance, the city center of Managua is only 50 feet above sea level, so it is always warm. There are hills in the city, especially on the south and southwest sides of town, that are elevate from 1,000 to 3,000 feet and can feel much cooler on a typically warm day.
Weather in general is fairly steady, with just a few degrees separating the warmest and coolest months. The cooler months are November-February. The warmest months are April and May.
There are two "seasons" in Managua, dry and rainy. The dry season is November-May and the rainy season is June-October. During the dry season, one can count on there not being any rain, so plan all the outdoor activities you like! In the rainy season, mornings are almost always clear. In the afternoon or evening is when the thunderstorms and rain comes. Conveniently, it mostly seems to rain at night time.
I hope this helped you understand a little about the weather in Managua!