Coastal Ecuador is often overcast, thanks to the Humboldt current coming up from Peru. But that also keeps temps more comfortable — doesn’t get as hot as many tropical coastal locations. Ecuador’s southern coast is the driest and the northern coast is the wettest and greenest. Rainy/humid season is October – April. (That doesn’t mean constant rain but you can have periods of intense rain and high humidity.)
When you visit, I’d avoid holidays, especially Christmas, New Year, Carnaval, Semana Santa (week before Easter) and the odd Ecuadorian holiday.