While the rest of the 11-strong discus field sprinted off the ground when the heavens opened Hall stayed his ground and threw a personal-best distance with his third and last throw.
Having unleashed his throw, Hall (22) bent over to shelter from the rain as the discus sailed 51.84m.
It was a personal-best distance by 31cm.
Hall, the New Zealand senior men's discus champion for the past two years, continued the form that won him a gold medal at the Oceania Championships in Cairns late last month.
His goal for the season is to throw 57m to qualify for next year's World Student Games.
If he does this he will break the senior men's record of 56.86m, held by Robin Tait (Ariki) since 1966.
Hall threw 46.54m and 47.30m with his first two throws and was scheduled to have another four throws until the heavy rain spoilt the plan.
"I wanted a personal-best throw at the start of the season," he said.
"The hard work I've done over the winter has paid dividends."
He has worked hard at the Academy of Sport gymnasium, lifted weights, and trained outdoors in the cold.
Hall was kept on his mettle by club-mate Kieran Fowler who won the silver medal behind him at the New Zealand championships at Christchurch in March.
Fowler (21), who started training after his club rugby season with the Pirates premier team finished in July, has a personal-best throw of 49.28m.
His first throw of 46.55m took him into the lead but he had time for only one more throw before the rain flooded the ground and ended the event.
Hall and Fowler have both represented New Zealand and are coached by Raylene Bates who is a coach with the New Zealand athletics team at the Commonwealth Games in Delhi.
They were pitted against another former New Zealand representative in Matt Dallow (38), who has a personal-best throw of 51m.
Dallow set a New Zealand junior decathlon record of 7478pts in 1991 before spending the next 15 years in the United States.
He has helped coach New Zealand Commonwealth Games discus thrower Beatrice Faumuina for the past three years.
Dallow won the masters men's aged-over-35 event with a throw of 41.12m.
An significant throw in the event came from former English schoolboy rugby representative Hamish Clapp (22), who finished third in the senior men's event with 39.59m, while Matthew Aitken (Hill City) won the men's aged 17 to 19 event with 24.53m.
Nicole Bradley (Caversham) won the junior girls hammer throw with 36.25m and Hamish Finnie (Hill City) the junior boys event with 40.06m.
Daniel Balchin (Caversham) dropped club-mate Bevan Stevens on the fourth-last lap and then battled through the heavy rain to win the men's 3000m in 8min 55.78sec.
The Wilson family dominated the women's sprints with Lauren winning the junior girls 100m in 12.28sec and the 200m in 25.21sec.
Her mother, Liz, won the masters women's over 35 100m in 13.60sec.
Brent Cheshire (Ariki) jumped close to his best when he won the men's aged 15 and 16 high jump with 1.80m.
