Wenzhou derives its present name from its climate, and has a humid subtropical climate (Köppen: Cfa) with short winters and long, hot, humid summers. Summers are similar to the remainder of the province (albeit slightly cooler during the daytime as compared to inland areas), but winter is much milder, partly due to the southerly location and partly due to the sheltering effect of the surrounding mountains. The monthly 24-hour average temperature ranges from 8.0 °C (46.4 °F) in January to 28.0 °C (82.4 °F) in July and August, while the annual mean is 18.08 °C (64.5 °F). Heavy rainfalls occur in late spring and early summer due to the plum rains of the East Asian monsoon, while typhoons are commonly a threat in the second half of summer causing considerable damage and destruction. With monthly percent possible sunshine ranging from 26% in March to 53% in August, the city receives 1,706 hours of bright sunshine annually.