receives moderate, though highly seasonal, winter-based rainfall. Summers are generally hot, sunny and dry, lasting from December to March, with February generally the hottest month. Winters are relatively cool and wet, giving Perth a hot-summer Mediterranean climate (Köppen climate classification Csa). Perth has an average of 8.8 hours of sunshine per day, which equates to around 3,200 hours of sunshine and 138.7 clear days annually, making it Australia's sunniest capital city. Summers are dry but not completely devoid of rain, with sporadic rainfall in the form of short-lived thunderstorms, weak cold fronts and on occasions decaying tropical cyclones from Western Australia's northwest, which can bring heavy rain. Temperatures above are fairly common in the summer months. The highest temperature recorded in Perth was on 23 February 1991, although Perth Airport recorded on the same day. On most summer afternoons a sea breeze, known locally as the "Fremantle Doctor", blows from the southwest, providing relief from the hot northeasterly winds. Temperatures often fall below a few hours after the arrival of the wind change. In the summer, the 3 p.m. dewpoint averages at around . Winters are cool and wet, with most of Perth's annual rainfall between May and September. Winters see significant rainfall as frontal systems move across the region, interspersed with clear and sunny days where minimum temperatures tend to drop below . The lowest temperature recorded in Perth was on 17 June 2006. The lowest temperature within the Perth metropolitan area was on the same day at Jandakot Airport, although temperatures at or below zero are rare occurrences. The lowest maximum temperature recorded in Perth is on 26 June 1956. It occasionally gets cold enough for frost to form. While snow has never been recorded in the Perth CBD, light snowfalls have been reported in outer suburbs of Perth in the Perth Hills around Kalamunda, Roleystone and Mundaring. The most recent snowfall was in 1968. The rainfall pattern has changed in Perth and southwest Western Australia since the mid-1970s. A significant reduction in winter rainfall has been observed with a greater number of extreme rainfall events in the summer, such as the slow-moving storms on 8 February 1992 that brought of rain, heavy rainfall associated with a tropical low on 10 February 2017, which brought of rain, and the remnants of ex-Tropical Cyclone Joyce on 15 January 2018 with . Perth was also hit by a severe thunderstorm