Residents of the Coromandel are being urged to be alert for severe thunderstorm warnings, rapidly rising river levels and surface flooding as heavy rain hits the region today and overnight.

Waikato Civil Defence and Emergency Management group controller Scott Fowlds says Civil Defence and Environment Waikato council staff are monitoring the impact of the rain on waterways.

"People on the Coromandel need to stay alert for problems such as rapidly rising river levels, surface flooding and greasy roads. They should keep up to date with news reports and MetService warnings in case the situation changes."

Mr Fowlds said EW had an extensive flood management system in place.

"EW will be ready to implement tried and true flood management procedures should they become necessary."

His comments came after MetService alerted EW to a slow moving system over the Coromandel Peninsula.

Heaviest rain is expected later in the afternoon and overnight, and there are expected to be accompanying thunderstorms.

Severe thunderstorm warnings are in place for north of the Waikato region and EW is monitoring the situation to see if a similar warning is required in its area.

Mr Fowlds said Waikato Civil Defence group is being kept up to date on developments by MetService and EW so that it can swing into action if necessary in response to the wet weather.

Auckland Civil Defence is urging Aucklanders to be on high alert due to the severe thurderstorm warning to the north of the Waikato, pointing to the potential for hazards such as flash flooding, dangerous driving conditions and fallen power lines and trees.

Mr Fowlds said a similar warning would be issued if necessary if it looked like the severe thunderstorms were heading down to the Waikato.