"People should keep an eye on the forecast in case there are any severe weather warnings issued and plan accordingly," Little said.
Monday morning had a low of 6.9C, slightly above the average temperature of 6.2C for this time of year.
Little said Monday would have a high of 18C.
"Monday is a great day to get out and about during lunchtime and have a little stroll around, because unfortunately the rest of the week won't be as sunny," he said.
Overnight temperatures this week will reach lows of between 8C and 9C, and drop to 5C early on Thursday morning.
"There is a clearance on Wednesday as the wet weather moves up the country but, unfortunately, the wet weather slides down again, so Thursday and Friday will see more rain in Whanganui," Little said.
The highs during the week sit around 15C to 16C, increasing to 19C on Friday.
Little said this was above the average temperature for this time of year, which generally sits between 13C and 14C.
"If you've got any washing you need dry, it's probably one of those weeks you'll want to check the forecast and plan accordingly," Little said.