The fog season is usually based in the cooler months (late autumn, winter and early spring).
[1] In the Tampa Bay area of Florida, the fog season is from December to February.
Sydney's fog season is longer, starting from April through to October.
It is not generally true that fog season in a given area is during autumn or winter (the cooler months); for example, the Japanese coast of the Pacific Ocean has a dense fog season from May to August.
The June Gloom, a cloudy and foggy phenomena, experienced in the southern coast of California occurs in late spring and early summer (May and June).