Planning for the weather is a good way to make your trip to Lake Tekapo relaxing and enjoyable, especially when you're splurging. The hottest months are usually February and January, with an average temperature of 7°C, while the coldest months are July and August, with an average of -3°C. The rainiest months in Lake Tekapo are May, September, December and July, with each month seeing an average of 360 mm of rainfall.