After continual torrential rain overnight Sunday and into early Monday, several Dannevirke streets were flooded when gutters and culverts couldn't cope.

Just after 6am the surface flooding had encroached on the Thyra St intersection and there was further flooding along Christian St.

After the rain came the low mist and then the steaming heat, with the temperature hitting 32C - made worse by the high 99 per cent humidity.

So far this month the district has had more than 50mm of rain, with Norsewood weather-watcher Lyn McConchie recording 10mm overnight Sunday, and another 11mm during a thunderstorm late Tuesday afternoon, giving her area 65mm.

"With no wind and the high humidity, it has all sunk in and done us some good," she said.

"We've only had one day in the month when we haven't had any rain at all."

Overnight Monday, lightning strikes lit up the sky over Dannevirke and Tuesday's temperature soared, again with exceptionally high humidity, before an early evening thunderstorm dumped 10mm of rain.