Downpour: How much rain fell on Whanganui's rainiest day?

Parts of Whanganui were under low cloud on Tuesday. Photo / Bevan Conley

Whanganui got some of the heaviest rain of the year on Tuesday - and it's needed to boost our water tables, Kauangaroa farmer Mike Cranstone says.

The weather station at Whanganui Airport recorded 23.6mm of rain that day, and 24mm was recorded at Cranstone's farm.

The subsoils there are still dry, he said, and the rain will soak in.

The heaviest falls were in the early afternoon, when 11.4mm fell in an hour.

Anything over 10mm an hour is considered heavy in an urban situation, MetService meteorologist Tahlia Crabtree said.

She said 2020 is tracking a little drier than 2019.

Across June and July 2019 there was 384mm of rain. So far this year the airport weather station has recorded 311mm.

A day with more than 5mm of rain is called a "rain day". In June this year there were 16 rain days.

So far July 2020 has had 12 rain days and could yet reach the month's average of 15. Whanganui has had a total of 76mm of rain this month - the average for July is 91mm.

After a hot summer and a long dry autumn the rain is so welcome, Cranstone said.

"We need to get wet in winter if we are going to have water in the water table to get us through next summer."

A lot of the region's farmers were short of feed going into winter, but that has eased. This winter's rain and mild temperatures have kept grass growing and most have enough feed to keep their stock until spring.

The winter has had some cold snaps, but they have been short and the weather has generally swung back to the northerly quarter and warmed up, Cranstone said.

The coldest day in June was June 9, with 2C, Crabtree said. The coldest day this month was July 14 which hit a low of 1C.

A southerly change is now predicted, with more showers, possibly heavy. Then the weather will shift back to a westerly flow, with a few showers, Crabtree said.

After that it will "fine up quite nicely" in time for the weekend, she said.