Further south, organisers of Wings over Wairarapa also face an anxious weather watch.
The opening day of the event was cancelled yesterday due to poor weather. Organisers said they will make a decision on the scheduled second day of the event this morning.
Adams said the showers looked set to continue in the region today.
"In the afternoon especially there's a chance one or two of them will be heavy, but hopefully not as bad as in Hamilton - the main thunderstorm risk is further north," he said.
"There's quite a moist air mass over the country, which is giving us the ingredients for these heavy showers and thunderstorms we've been seeing. That is set to continue [today]."
In Christchurch, where residents are crying out for rain to put out the hugely destructive fires in the Port Hills, there could be a few showers in the morning but it was mostly looking like a fine day.
"It looks like best chance of showers will be around Thursday," Adams said.
Next week would be "hit and miss" for the country, with some rain in the west, but mostly a dry week for the North Island. The South Island see another front moving in from Tuesday.