Humidity is commonly between 70 and 80 per cent in coastal areas and is about 10 per cent lower inland. It varies inversely as the temperature, falling to a minimum in the early afternoon when temperature is highest and frequently lying between 90 and 100 per cent during clear nights. As the following table shows, the diurnal variation is greater than the difference between summer and winter.
|Station||Mean Relative Humidity|
|3 a.m.||3 p.m.||3 a.m.||3 p.m.|
|Auckland (Mechanics Bay)||85||63||90||74|
Very low humidities – between 20 and 30 per cent or lower – occur at times in the lee of the Southern Alps where the Fö effect is often very marked. In summer the hot, dry “Canterbury Norwester” is generally a most unpleasant wind. Cool south-westerlies are also at times very dry when they reach eastern districts. In Northland the humid midsummer conditions are inclined to be rather oppressive, though temperatures there rarely reach 85°. Dull, humid spells are generally not prolonged anywhere, but their frequency shows a marked increase in the south.