"There's likely to be thunder [overnight last night], and [today] there's a possibility of hail in Northland. There was hail [yesterday] in Auckland and there's a chance that will spread north," he said.
"There will be showers, some of them heavy, [today] and into Friday before things clear up for Saturday. The wind will be severe at times, before easing up for the weekend."
Mr Adams said daily highs in Northland between now and the weekend will be around 13C to 14C while overnight lows would get down as low as 4C, making hail a possibility.
"That wind won't make you feel that you are warmer, but it's certainly a lot warmer than the rest of the country."