Rainfall tends to be associated with Atlantic depressions or with convection. The Atlantic depressions are more vigorous in autumn and winter and most of the rain which falls in those seasons in the south-west is from this source. Average annual rainfall is around 980 millimetres (39 in). November to March have the highest mean wind speeds, with June to August having the lightest winds. The predominant wind direction is from the south-west.

Along with convection, what provokes rain in the Plymouth area?