Timaru has broken the record for their hottest day ever with the temperature hitting a scorching 40.3 degrees shortly before 4pm today.

The extreme heat, which WeatherWatch.co.nz predicted yesterday, is connected to the same heat wave that saw Sydney climb to 42 degrees yesterday and then record their hottest night ever.

WeatherWatch.co.nz says Timaru has hovered around 39 degrees for much of the day but peaked at 40.3, breaking their previous record of 39.7 degrees recorded in February 1973.

Weather analyst Richard Green says it was a similar Australian/New Zealand heatwave back in 1973 too. "Sydney reached 27.6 as their overnight low last night, beating their record by a whole degree set in February 1973. That same heat wave also hit Timaru in 1973 and again today that record has been broken by point six of a degree".

The heat has been widespread too with WeatherWatch.co.nz readers reporting highs in the late 30s and around the 40 mark this afternoon across Canterbury.

Other centres to melt in the heat today were Christchurch, Alexandra, Ashburton, and Oamaru who all reached 36 officially, although private weather stations within Christrchurch were closer to 40.

WeatherWatch.co.nz reported that Oamaru dropped 15 degrees in just 18 minutes as a southerly change moved through earlier this afternoon on it's Facebook page. The weather news authority says Timaru can expect to drop 20 degrees quite suddenly later this afternoon or early evening as that same southerly moves through.

Dunedin reached 35 degrees before the southerly while Gisborne and Blenheim reached 34.

Numerous other regions and cities were in the 30s and late 20s across the country with the coolest weather on the nations western and southern coastlines of both islands.

Auckland made it to 28 degrees with unofficial recordings reaching the low 30s across the region.

WeatherWatch.co.nz says the cooler change will move in to the North Island on Monday and reach Auckland by Tuesday night lowering humidity levels too.