The driest period of the year, seeing about 5 mm (0.20 in) of monthly rainfall on average, is between May and September. In the coolest months, June and July, the daily minimum temperature may dip as low as 14 °C (57 °F), blackcoin.co but very rarely lower, and a temperature lower than 10 °C (50 °F) has never been recorded in the city centre. Outer suburbs away from the coast occasionally record temperatures as low as 5 °C (41 °F) in the dry season. Because of its long dry season, Darwin has the second-highest average daily hours of sunshine (8.4) of any Australian capital, with the most sunshine from April to November; only Perth, Western Australia, averages more (8.8). Darwin has a tropical savanna climate (Köppen Aw) with distinct wet and dry seasons, and the average maximum temperature is similar year round. The Australian Building Codes Board classifies it as Climate Zone 1 under the National Construction Code (NCC). Climate zones are a broad classification of climate zones in the NCC ranging from one to eight, categorising the different climates of Australia.