"And Sunday evening will get down to 9C."
Makgabutlane said Whanganui also had a record-breaking overnight temperature on Thursday, reaching the warmest minimum for August of 16.4C.
This was 2.6C higher than the previous record of 13.8C set in 2015.
"The average minimum temperature for August in Whanganui is 6.4C, so Thursday night reached 10C higher than the average.
"The cloudy weather will be adding to the warmer overnight temperatures."
Sunday reached a maximum temperature of 20.1C around 1pm.
"Which is still 6C warmer than the average August temperatures in Whanganui," Makgabutlane said.
She said Whanganui residents could expect possible showers into Monday.
"Then it looks like a couple of dryer days, until Thursday where there is another bout of rain going into the first part of Friday."
Temperatures would average between 16C and 18C for the start of the week, so it's starting to head back towards average August temperatures, Makgabutlane said.
She said the wind will have died down through the start of the week, but there is a shift expected from the northerlies experienced last week to southerlies around Friday.
