Warm, wet and windy weather is expected for the rest of the week in the Whanganui region.
MetService meteorologist David Miller said light occasional rain could be expected across the region from Thursday to Sunday.
He also expected northerly winds of up to 90km/h in exposed areas on Thursday.
Those high winds were expected to begin to reduce on Friday and continue to calm down across the weekend, though occasional showers would continue throughout.
Miller said abnormally high temperatures for this time of the year in Whanganui were expected both in the daytime and at night for the rest of the week.
"We're looking at highs of 20 and 21 over the next few days ... which is pretty warm for August, and overnight lows of 15 and 16."
He said the high temperatures were being caused by a mass of warm, humid northerly air originating from the tropics which was affecting the entire country.
"Basically a big high to the east of the country is just sitting there for the next few days and that's directing a northerly flow onto the country."
The high-pressure system was causing humid winds to blow across New Zealand and was also causing the heavy rain on the West Coast of the South Island this week.