Hyderabad has a tropical wet and dry climate (Köppen Aw) bordering on a hot semi-arid climate (Köppen BSh). The annual mean temperature is 26.6 °C (79.9 °F); monthly mean temperatures are 21–33 °C (70–91 °F). Summers (March–June) are hot and humid, with average highs in the mid-to-high 30s Celsius; maximum temperatures often exceed 40 °C (104 °F) between April and June. The coolest temperatures occur in December and January, when the lowest temperature occasionally dips to 10 °C (50 °F). May is the hottest month, when daily temperatures range from 26 to 39 °C (79–102 °F); December, the coldest, has temperatures varying from 14.5 to 28 °C (57–82 °F).