Portugal has relatively mild winters and hot summers. Spring is a great time to visit Portugal and it start at the end of March. In late March and beginning of April average daytime temperatures are around 18-20°C. Light rain is common, but mostly you can expect sunny skies. Sometimes temperatures rise to summer-like 25°C.
In Galicia, the weather is slightly cooler in the same period. The average daytime temperature is around 15-16°C, while the average night temperature is around 8°C.