Heavy rain, severe thunderstorm possible in Northland today

The MetService has issued two weather watches for Northland this afternoon - one for heavy rain and the other for thunderstorms

Northland has two weather watches issued by MetService today, with one saying heavy rain is likely across much of the region and the other pointing to localised severe thunderstorms that will also bring plenty of rain.

Rain is expected to become widespread in Northland this afternoon, with embedded thunderstorms, which could continue through to early Tuesday morning.

There is a moderate risk that one or two of these thunderstorms could become severe producing localised downpours of 25 to 40mm per hour.

Rainfall of this intensity can cause surface and/or flash flooding and may lead to slips and hazardous driving conditions.

Northland has had three heavy rain watches in the past two weeks, but much of the heavy rain predicted — in one case up to 100mm in 24 hours - did not eventuate to those levels.

MetService Meteorologist Tom Adams said a weather watch is effectively a 'head's up' that the kind of rainfalls, etcetera contained in the weather watch, could happen. A warning is the MetService saying that the conditions in the warning are almost sure to happen.

''We issue a watch first then once we get pretty much sure it's going to happen we then issue a warning - they are two different things.''

Mr Adams said today's thunderstorm watch would likely see very localised outbreaks of thunderstorms that would also bring rain.

''Sometimes those thunderstorms only cover several hundred metres or a few kilometres so are very localised.''

The thunderstorm watch will run until 6am tomorrow while the heavy rain watch will run until 9am tomorrow.

Mr Adams said for the most accurate and up-to-date weather information, including any weather watches or warnings people can go to www.metservice.com or to their Twitter feed @metservicewarn .