Leaden skies brought spells of rain, while there was no breath of wind to blow along the clouds.
After a frustrating few hours spent twiddling thumbs, conditions improved for a 24 overs-a-side game starting at 3.15.
In stark contrast to the weather, Yorkshire won an exciting contest by two wickets with one ball to spare, climbing to second in the North Group, one point behind leaders Worcestershire having played a game more.
After the visitors won the toss, Derbyshire scored 189-6, opener Ben Slater striking an unbeaten 109 from 82 balls with 13 fours and a six, his fourth one-day hundred.
David Willey, making his first appearance of the season after returning from the Indian Premier League, took 4-47 from four overs, his best figures for Yorkshire in any format, eclipsing his 3-34 in the quarter-final of this competition against Kent at Canterbury in 2016.
Although the England all-rounder, batting at No 3, was dismissed for a third-ball duck in the chase, top-edging a pull to mid-wicket, the visitors were indebted to Tom Kohler-Cadmore, who top-scored with 81 from 63 balls with five fours and four sixes.
But it was pace bowler Matthew Fisher who won it at the end, the No 10 striking an unbeaten 24 from eight balls with three fours and a six, showing a composure beyond his 20 years.
In muggy conditions, and before a crowd of about 500, Yorkshire made one change to the side that beat Leicestershire by nine wickets on Sunday, teenage batsman Harry Brook left out to accommodate Willey.
Initially, Willey struggled, conceding 21 from his first over – the second of the innings – as Yorkshire failed to find the right lines and lengths.
There were four boundaries in the over as Willey, bowling from the City End, was pulled by Billy Godleman before Slater then flicked him off his pads, off-drove him and pulled him emphatically to the damp boundary rope.
On a pitch that offered good bounce and carry, Yorkshire, in those early stages, bowled much too short, Slater also feasting on a couple of half-trackers from Fisher, one of which flew for six towards the pavilion to raise the 50 stand for the first wicket from just 30 balls.
Having reached 52-0 from the first five overs, which constituted the powerplay, Derbyshire gradually fell away like someone who has fallen in with the wrong crowd.
Yorkshire pulled it back well, Tim Bresnan impressive on his way to 1-19 from four overs with just one boundary conceded, Slater the only batsman to pass 21.
At the halfway stage, Derbyshire were 97-1 and threatening a total well over 200.
Adil Rashid played his part in stymieing the run-rate, and he also got rid of Slater’s opening partner, Godleman, the Derbyshire captain well caught at deep mid-wicket by Bresnan.
Bresnan’s wicket arrived when Wayne Madsen hooked him to Cheteshwar Pujara down at long-leg.
Luis Reece was forced to retire hurt with a nasty-looking foot injury, sustained running between the wickets, before Willey nipped in with his four-wicket burst.
Gary Wilson was bowled as he attempted to paddle, Matt Critchley was caught behind as he tried to flick to leg, Alex Hughes was taken at deep mid-wicket and Daryn Smit caught slicing to cover.
After Yorkshire’s reply began with a maiden from off-spinner Madsen, Adam Lyth and Kohler-Cadmore injected impetus with four sixes in five balls, striking two apiece.
Lyth skied to mid-on in the fifth over before Willey was dismissed, and Yorkshire slipped to 71-3 in the ninth when Pujara was adjudged lbw to leg-spinner Critchley. There was a pivotal moment in the 13th over with the score standing at 87-3.
Gary Ballance, on 11, was badly dropped by substitute fielder Callum Brodrick at deep cover off Critchley, a reprieve that came back to bite the hosts.
Yorkshire added another 45 before Ballance was dismissed, bowled trying to scoop Duanne Olivier.
It triggered a mini-collapse, Yorkshire falling to 133-5 when Bresnan nibbled at one from Rampaul and was caught behind, and to 135-6 when Jonny Tattersall went lbw to the same bowler three balls later.
Rashid then edged Rampaul behind and Kohler-Cadmore struck him into the hands of deep mid-wicket, the West Indian finishing with a career-best 5-48.
It was anybody’s game at that point, but Fisher held his nerve, proving – as if proof were needed – that he is a young cricketer of the highest stamp.
Willey said: “We didn’t play to our potential but we got across the line. We were probably down by five, 10 per cent in all three departments which made for a tighter game than we would have liked.
“In my first over I bowled too short and got hit square of the wicket. So on a personal level, disappointed with my performance but we got across the line which is the main thing.”