Meanwhile, a lower level status yellow wind warning will apply for the entire country for 24 hours from noon tomorrow.
"Falling onto already wet ground, 20-40mm of rainfall is expected quite widely with 50-60mm possible over higher ground in Cumbria".
The third storm of the year could bring wind gusts of up to 70mph and the charts show Northern Ireland will be the first area to be battered by the severe weather conditions.
"We've got bands of sleet and snow pushing eastwards through the morning, and this will clear to heavy showers through the day".
"Gusts of 50-55mph are likely inland and up to 65mph along western coasts." said Mr Gundersen.
This warning will be in place from Tuesday 12 March 2019 12:00 to Wednesday 13 March 2019 09:00.
Waves crash against the seafront and railway line in Dawlish Credit Getty
It will be dry in many parts with sunny spells; however, a few showers will occur, chiefly in parts of the west and north.
In addition to the strong winds, Storm Gareth will bring some heavy rain for parts of the United Kingdom overnight Monday into Tuesday, particularly across northern England where a yellow warning for rain is in place from midnight tonight to midday tomorrow (Tuesday).
This means the alerts are now in affect for large parts of Northern Ireland, most of England and southwest Scotland.
Lasting from 6pm today until 6am on Tuesday, 25mm of rain is expected to accumulate as heavy brain rain turns to squally showers.
As the weather becomes warmer in the afternoon, the snow and sleet with transform over to rain.