Eve Thomas placed second to also qualify for worlds with Caitlin Deans in third.
There were huge celebrations in the men’s version of the same event with Fairweather’s training partner Zac Reid locking in his World Championship spot.
The 23-year-old powered home over the last 100m to take the win in a time of 3:47.87s.
Reid had missed out on qualification in the 800m and was ecstatic on seeing he’d qualified in the 400m, slapping the water in celebration before his good mate Clareburt swam over to give him a hug.
“That was fantastic, I was so emotional,” said Reid.
“It’s been a long journey to get back to this point after surgery so I’m just so happy to make it to worlds.”
Reid had hip surgery after representing New Zealand at the Tokyo Olympic Games. This is the first time he has qualified for the New Zealand team since then.
Lewis Clareburt was second and Louis Clark third.
In the men’s 400m freestyle multi-class event another New Zealand record fell with David Beck (Mt Eden) swimming home in a time of 4:44.18s. Jack Bugler (Blenheim) was second, with James Haydon (Parnell) third.
In the 400m freestyle women’s multi class Gaby Smith (S10) qualified for the World Para Swimming Championships with a time of 4:58.44s.
“It’ll be my second World Champs which is a pretty big achievement for me, I’m really happy to be going and it looks like we’re going to have a great team this year which is a great motivation.”
On the night where he was crowed the 2022 International Para Swimmer of the Year, Cameron Leslie won the men’s 50m backstroke multi class in 42.64s. Fellow Paralympian Jesse Reynolds claimed the silver in a S9 New Zealand Record with a time of 30.74s. Guy Harrison rounded out the podium for third.
Andrew Jeffcoat locked in his second qualification for the upcoming World Championships, swimming a 24.85s in the 50m backstroke. Zac Dell was second and Finn Harland set an age group record (17 years) 25.67s to place third.
The closest swim of the meet then came in the men’s 100m fly with Clareburt beating Cameron Gray by one-hundredth of a second in an epic battle.
Clareburt came from behind to win in a time of 52.54s with Gray posting 52.55s.
“That was a great battle,” said Clareburt. “He smoked me at the start but I somehow managed to hang in there.”
Christopher Elson was third.
Asher Smith-Franklin then set another New Zealand record in the men’s 100m fly multi class, with a time of 1:02.35s.