It all finished with the two running laps of 2.5km around Kowhai Park and back.
Jackson-Grammer's official recorded time of 58.79 minutes was pleasing for the Manawatu Triathlon Club member, who is looking towards the ITU World Triathlon Grand Final in London in September.
Competing every fortnight through the recent drought, he was also pleased to have some overcast conditions and a little precipitation to ease the journey.
"It was better, it's been hot lately.
"It's a good course. The swim was quite hard with the current - I was pushing up to the side and it was pushing me out."
Jackson-Grammer came back from an eight-month injury last year, just starting with his running before getting back on the bike and into the water.
The fastest woman home was local Margaret Tyson in one hour, 11.45 minutes.
Quickest men's team of Gareth Wright and Tom Osbourne were only 24 seconds over the hour. Best mixed team was Kim Whyte, Simon Becket and Grant McLeod in 1.06.50.