It was the young Scarlets who played the conditions better, their forwards retaining the ball and winning the collisions.
The front row of Javan Sebastian, Torin Myhill and Bradley Davies were particularly effective and set the platform for the game with their dominance in the scrum.
Playing into a strong wind, the half backs Maynard and Gareth Rees worked the ball well and made sure they went into half time 13-8 up courtesy of a try from Adams.
The second half saw the Blues struggle to clear their lines in the strong winds. Maynard took advantage by adding two penalties and from there on in, they didn't relinquish the lead.
More pressure on the Blues amounted to a try for Evans who pounced on a loose pass to score.And although the Blues threw everything at them to get back into the game, the Scarlets held on.
Blues Academy Manager Richard Hodges said after the match
"Obviously we are hugely disappointed to have lost the game today but I'm sure once the dust settles we can take pride in our performances over the season.
"Today isn't the right result for us but we have gone unbeaten all season but lost one game by one point, which was the final.
"We had a few injuries during the week leading up to the game but all credit to the Scarlets they deserved the win.
"We came flying out of the blocks in the first half with the wind at our backs and scored 10 unanswered points and if we'd have scored once more it may have broken them.
"However, the Scarlets did well to come back strongly and dominated the opening quarter of the second half and get some points.
"Some errors in the poor conditions cost us and we found it difficult to get any territory."
"Next season we will come back strongly as seven of the boys who were in the starting XV today will be playing for us next year and will learn from this experience."
Scarlets Academy Manager Kevin George believes his young players have the ability to emulate the likes of Rhys Priestland and George North after they were crowned on Sunday.
"Things go in cycles but this is the best group of boys I've had through," he said.
"A few years ago we had the likes of Rhys Priestland, George North and more recently Sampson Lee come through and this group measures up to that.
"We think things are going right for us at the moment and hopefully we can get another breed of internationals coming through."