As a rule the further south and inland you go, the greater variation there is in temperatures, summer and winter, day and night. For example at Kaitāia, average temperatures vary by 7.5°C from January to July. At Invercargill this variation is 8.8°C. Inland, in Alexandra, Central Otago, the annual range extends to 14.2°C. Waiōuru, in the centre of the North Island, has a 10°C annual variation. The sea, which is a massive body of liquid whose temperature varies only a few degrees over the year, regulates coastal temperatures.