Even as the rain stopped, the tears began flowing.
Lowry, the 32-year-old Irishman with stout nerves and a soft touch around the greens, endured the worst weather of the week and the Sunday pressure of a sellout crowd cheering him along to win the British Open by six shots.
He closed with a 1-over 72, the first time since 1996 that winner was over par in the final round, and it was no less impressive. More difficult than the rain was wind strong enough to break an umbrella. Lowry began making bogeys on the back nine of Royal Portrush without losing ground.
Ultimately, the outcome was never in doubt. No one got closer than three shots all day.
And thousands who filled these links off the North Atlantic could sense it when Lowry, after his fourth bogey in seven holes, rolled in an 8-foot birdie putt on the 15th hole to stretch his lead to six shots over Tommy Fleetwood.
When his approach to the 18th was just on the fringe, he smiled broadly and stretched out his arms, hugging caddie Bo Martin. The loudest cheer of a noisy week was for a tap-in par that made Lowry a major champion.
Fleetwood had to settle for his second runner-up finish in a major. He closed with a 74. Conditions were so rugged that no one from the last 12 groups that teed off in the final round broke par.
Brooks Koepka, who started seven shots behind, began with four straight bogeys and shot 74 to tie for fourth.
Royal Portrush had to wait 68 years for another shot at hosting golf's oldest championship. Lowry made it worth the wait. So strong is support of the Irish golf community that Padraig Harrington of Ireland and Graeme McDowell waited for Lowry when he finished.