Ecuador, true to its name, straddles the equator. This means that there is little change in daylight hours, and little seasonal variation. This also means, then, that it is always a good time visit Ecuador!
The rainy season occurs from January to April, and so beachgoers should consider planning their vacation around those wetter months, although it is hotter in the rainy season. Temperatures stay high year around, from about 80F to 92F.
During the wet season, the highlands do not experience a lot of rain; but the “dry” season sees a fair amount of rain. Although directly on the equator, the highlands are not as hot; for example, Quito rarely heats up above 88F, but because of its elevation, can cool down to about 40F.
The Amazon region is always hot and always humid. The wettest months are June, July, and August. Temperatures average 85-90F, and drop to about 68F at night.