Fiordland directly faces the Tasman Sea, and the unpredictable westerly winds that blow across it. As a result, the weather can change rapidly. The winds cause orographic precipitation - the rain that occurs when air masses are forced over an increase of elevation. The annual rainfall amounts to around 8000 mm at Milford Sound, whereas nearby Te Anau may experience annual rainfall that is below average. Nevertheless, Fiordland is considered to be one of the wettest places on earth.
Daytime summer temperatures range from 17° to 22° C. Winter temperatures vary between 10° and 14° C while the air is clear and refreshing. The interplay between peaks and fiords causes the weather to be localised, whereas the mountains act as a barrier between Fiord- and inland. Avalanches represent a danger year around but primarily during springtime.