William Flack, 15, was metres behind the couple, on his way to a friend's house after his NCEA science exam. "I saw the man and his wife ahead and I was walking faster than they were, so I was catching them up when the branch came crashing down onto them."
William ran to the man - he had been struck a heavy blow but was conscious and gave his cellphone to the teen to call 111.
Greytown fire chief Harry Howard said: "By the time we got there, there were about a dozen people helping out and had got them out from under the branch."
The couple were taken to Wairarapa Hospital - the man with serious head injuries and the woman with a fractured leg, a St John Ambulance spokesman said.
Wairarapa Hospital spokeswoman Jan McLaren said the man and his wife were both in a serious condition, but stable.
Mr Howard said the couple were lucky to have survived.
"It was extremely unlucky for the couple to have a big hunk of tree land on them, but they were also extremely lucky that they weren't killed because it was a very big branch."
Strong winds also battered the top of the North Island and fanned a large scrub fire at Horeke, near Kaikohe.
Fire Service spokeswoman Megan Ruru said five helicopters and two ground crews worked to put the blaze out. They would return at first light today.
In the South Island, a woman and her baby stranded in their car were plucked to safety by a railway work crew at Totara Flat after the Grey River breached the stopbank upstream at Ikamatua.
And earlier in the day, a 70-year-old farmer nearly drowned near Greymouth while trying to rescue his sheep from floodwaters.
He was rescued after a passerby saw him struggling in the water.
Last night, Civil Defence was on standby in Greymouth as the swollen Grey River continued to rise. Grey District Mayor Tony Kokshoorn said the river was at its highest level since 1997.
Floodwater barriers were being set up yesterday to prevent waters reaching suburban Greymouth.
Slips forced the closure of the Arthurs Pass and the Lewis Pass, so the only road route to the West Coast was via Nelson.
Further north, the MetService reported wind gusts of 130km/h in central Wellington, where northwesterlies uprooted trees and damaged houses.
Air New Zealand said the pilot of a jet twice tried to land at Wellington Airport, but had to turn back to Auckland. Passenger Marguerite Christophers of Wellington said there were "a lot of white knuckles" and one person needed oxygen as the plane tried to land. "I've never experienced a bumpier ride."
Off Tauranga, salvors battled winds of up to 75km/h to remove a further 15 containers from the stranded cargo vessel Rena, bringing the total salvaged to 64.
While parts of South Island shivered in single-digit temperatures yesterday, parts of the North Island were above 26C.
MetService weather ambassador Bob McDavitt said the dry, warm spell in Auckland was likely to end on Thursday as strong southwesterlies hit most of the country, bringing snow to highlands in the South Island and cold rain to the North Island.
additional reporting: APNZ, Herald Online
