With the pressure on, a wayward return into the net from Griekspoor handed the Briton the opening set in 50 minutes.
With the second set tied at 1-1 and Evans 30-love up in the third game, play was suspended as rain began to fall. It proved, though, only a brief delay and the players did not leave the court before the match resumed.
However, Swedish umpire Mohamed Lahyani was soon again out of his chair as the drizzle continued – with Evans, leading 2-1, looking less than impressed as he sat under an umbrella for another few minutes before play was allowed to continue.
Griekspoor levelled things up on serve, but the players were forced off because of a lightning warning in the area.
Play was suspended again just before 6.30pm local time, this time looking set for a more lengthy delay and with spectators also having to leave the stadium.
The players and spectators finally returned to court more than 90 minutes later, where Evans resumed right where he left off.
He cruised through his remaining service games and dictated play on return, not facing a break point until his final game on serve.
But Evans held his nerve, saving four break point opportunities before claiming victory with a service winner.
Evans entered the event on a seven-match losing streak but won 10 straight sets en route to the title, eclipsing second seed Frances Tiafoe and fifth seed Grigor Dimitrov in the process.
It is Evans’s first ATP title since Melbourne in 2021.
