Winter starts officially on June 21st and goes until September 23rd in the Southern Hemisphere.
As João Pessoa is located almost at the Equator, it means days and nights last 12 hours each. The sun rises at 5:30 am and sets at 5:30 pm, regardless of Summer or Winter.
The seasons are not well defined, except in Winter it becomes mild, rainy and overcast and in Summer it's hot and sunny all the time.
It never gets cold in João Pessoa. The occasions when the temperature "drops" to about 73°F, the local inhabitants start wearing jackets, which looks quite amusing in the eyes of the tourists that come from places where there's a real winter.
Storms are rare and even when it rains, the sun comes out every day for at least a couple of hours. The inhabitants usually don't go to the beach on such days because of the "cold water", which is obviously not cold at all. The water gets a muddy color because the sand gets mixed in it like in a suspension.
The rain season is also the best period to go to the waterfalls due to the flooded rivers.