Today would bring a daytime high of 17C, with a overnight low expected to be 9C.
Things would improve on Sunday, Hines said.
"There could still be some showery weather to start off but there will be brighter skies for a lot of the day, with a mixture of sunshine and cloud for the second half.
"It will still be a little windy though.
"West to south-westerlies will be blowing with a bit of velocity throughout most of the weekend."
A high of 15C was expected for Sunday, with a low of 9C again overnight.
Hines said temperatures would drop for the start of next week.
"It will be fairly cloudy for Monday, Tuesday and maybe into Wednesday, with brief spots of rain.
"Those (daytime) highs are looking to be between 12C to 14C through most of next week, with overnight lows dropping as well, maybe 3C to 4C.
According to NIWA (National Institute of Water and Atmospheric Research), temperatures in the Whanganui region were very likely to be above average for the next three months (September to November).
More northeasterly winds and marine heatwave conditions may cause increased sunshine and warmer temperatures.
Rainfall totals were predicted to be near normal or below normal.
Fewer spring westerlies may increase the risk of dry spells.
Soil moisture levels and river flows were most likely to be near normal.
