Makgabutlane said Whanganui was experiencing similar weather conditions to the rest of the country, brought on by a high-pressure system over the Tasman Sea.
"When there is a high sitting over the Tasman it causes a low in the adjacent area and that will last until a new low comes and pushes it off."
Temperatures are set to stay low with a high of 16C and an overnight low of 9C on Monday.
The wet weather is forecast to ease off to occasional showers over the next two days as temperatures continue to fall with a high of 14C and an overnight low of 3C forecast for Wednesday.
A northwesterly change will bring warmer weather on Thursday which is forecast to have a fine start and likely to become cloudy with light rain or drizzle possible from the evening.
Friday is likely to be the best day of the week with fine, settled weather and a high of 17C followed by an overnight low of 11C.
The temperature is forecast to climb to a high of 19C for both days on the weekend as northwesterlies continue.
A cloudy day is forecast for Saturday with an overnight low temperature of 11C and the rain is set to return on Sunday continuing throughout the day.