'Reset' minimum temperatures at Christchurch and forecast accuracy
In some circumstances the daily climatological minimum temperature recorded about 9am is the temperature to which the minimum thermometer was reset 24 hours previously. This paper investigates the frequency and magnitude of such 'reset' events at Christchurch Airport. Differences between the overnight minimum temperature and the climatological value of up to 9°C have been found in individual cases. Differences up to 1°C have occurred in the corresponding monthly averages. It is shown that errors in both overnight minimum temperature forecasts and their subsequent verification may arise if climatological data containing reset minima are used in their derivation.