Although that is chilly, it is nowhere near the lowest temperature ever recorded for Whanganui in July: -2.6degrees in 2001.
After a cold start to winter in June, the region was warmed by northwest and westerly winds that brought the rain.
There were huge variations in rainfall across New Zealand. Auckland and the Coromandel Peninsula had flooding on July 7, and massive rainfall on the South Island's West Coast caused slips and road closures on July 16.
The largest amount of rain to fall in one day was 246mm, in Milford Sound on July 6.
One of Whanganui's bands of rain, on July 8, came with strong winds that caused 500 power outages.
Most of New Zealand's west coast got average or above average rainfall, while Northland and the East Coast, Kaikōura and Canterbury were very dry.
Whanganui wasn't alone in being warmer than average.
New Zealand had the fifth warmest July on record, National Institute of Water and Atmospheric Research (Niwa) meteorologist Ben Noll said.
The other warmest Julys were all in the past 10 years: 1998, 2000, 2005 and 2013.
The average temperature across New Zealand last month was 8.9degess, which is 1.1degress warmer than the average for the past 30-40 years.
In the Manawatū/Whanganui region temperatures were 0.5degrees to 1.2degrees warmer than normal.
Surrounding towns Hawera, Palmerston North and New Plymouth recorded third and fourth highest ever average temperatures in July.
The highest temperature recorded in July was 22.3degrees in Kaikōura, and the lowest was -7.6degrees in Middlemarch.
The westerly rainfall pattern is expected to continue into August in Whanganui, with warmer than average temperatures for the first two weeks.