The weather here in Santiago de Los Caballeros is virtually always PARTLY SUNNY. Which, conversely, means that it is nearly always partly cloudy. While it’s always warm, I think it could do with a bit more sun quite frankly. It gets less sun than its coastal cousins Puerto Plata and Sosua and is slightly cooler as well.
Some basic points to bear in mind when it comes to weather in Santiago, Dominican Republic:

• almost every day is partly sunny/partly cloudy,
• it is always quite warm, but not as hot as Sosua/Puerto Plata,
• weather can change from being sunny to rainy vary quickly, and back to sunny again,
• there are not very many TOTALLY sunny days, and I regret this fact.

My favorite caribbean location for sun is December to March in Barranquilla, Colombia: wow! Three months of near total sun, all day long.