Average Temperatures in the South Island in April
Broadly speaking, South Island temperatures in April are relatively mild, with some warm days and some cool nights. Knowing what to expect, however, depends largely on where you plan to go on your South Island itinerary.
You can still enjoy some lovely, warm days over 20°C during April in Nelson, with an average daily high of 18.1°C (64.6°F). The average nightly low is 8.3°C, with an overall average temperature of 13.2°C.
Crisp days and clear skies are a feature of April in Queenstown, with an average temperature of 9.7°C (49.5°F) across the month. Daily highs average 15°C, but often push higher on sunny days. They are balanced out by cool nights, though not freezing, with average lows of 4.3°C.