During summer Auckland rainfall averages about 3½ in. a month. It becomes more frequent towards the end of autumn, reaching a maximum in June and July, each averaging 5½ in. of rain and 20 rain days, compared with only 10 rain days both in January and in February. The mean annual rainfall is 47–50 in., increasing to 55 in. near the Waitakeres. Rain days average 185 per annum and 100 of these have at least 0·1 in. of rain. Once in 20 years a fall of 5·5 in. may occur within 24 hours and 1·8 in. in one hour. In the last 90 years the longest period without rain was 39 days. Although the most frequent winds are from west and south-west, winds from other directions are common; a relatively large proportion of the strongest winds are from the north-east. Strong gales, with gusts over 60 mph, occur about twice a year. February, with a mean temperature of 67°F, is the warmest month and July (51°) is the coldest. In July the mean daily maximum and minimum temperatures are 57° and 46 respectively compared with a mean daily range from 74° to 61 in February. Temperatures normally reach 80° on only five days a year, but there are many days with maximum temperatures over 75° (45 per annum). These, too, are rather oppressive, due to the high humidity prevailing. Frosts generally occur only in sheltered low-lying parts of the city. There is no snow in winter. Sunshine averages 2,100 hours per annum; it is 50 per cent of the possible amount in summer, but only 42 per cent in June and July. Fog in the city occurs about eight times a year, mostly in autumn and winter, but almost invariably is confined to the night and early morning. Hail occurs about four days a year, mostly in winter, but causes negligible damage. Thunder is heard about nine days a year.