 During summer months – from the last Sunday in September until the first Sunday in April – daylight saving time is observed and clocks are advanced one hour.New Zealand Daylight Time (NZDT) is 13 hours ahead of UTC, and Chatham Daylight Time (CHADT) 13 hours 45 minutes ahead.New Zealand's associated states – the Cook Islands and Niue – and the dependent territory of Tokelau use several different time zones at their own discretion.