Wales, beaten only twice in 19 internationals at this level, were never headed after taking command with the wind at their backs in the first half.
They piled up 13 points in the first period and Ireland never looked like coming back.
Wales scored the only tries of the match, centre Gareth Thomas getting the first after eight minutes and fellow centre Richard Jones scored the other just before half-time. All the other points came from the boot, fly-half Arwel Thomas kicking two penalties for Wales and full-back Brian Begley a hat-trick of penalties for Ireland.
The mud and howling gale made sure the match would never be a great spectacle but the Welsh pack did enough to earn their side victory with virtually all the handling rugby coming from the home side.
In the provincial Super Ten competition, full-back Matthew Pini scored three tries as Queensland beat Tonga 32-20 on Friday and extended their unbeaten record. Queensland, who strengthened their grip at the top of Pool B with their third consecutive win, raced to a 22-0 lead at half- time against the Pacific islanders.
Tonga reduced the deficit to five points through tries by forwards Falamani Mafi and Ipolito Fenukitau and accurate kicking from full-back Sateki Tu'ipulotu, who landed two conversions and two penalties.
The Australia Test flanker Ilie Tabua sealed Queensland's victory when he surged past four Tongan defenders to score a try six minutes from time. The Queensland forward John Eales was successful with three conversions and two penalties.
The Scottish international full-back Michael Dods has followed the same route into the Courage League taken by his Gala team-mate Gregor Townsend by signing for Northampton.
Dods, capped twice on the tour to Argentina last year, has registered with the Saints for next season, just days after Townsend signalled his intention to move to Northampton.
Dods will take the number of Scots at Franklins Gardens up to five, with the capped flanker Peter Walton, the provisional World Cup squad scrum- half Brett Taylor and centre Rob MacNaughton already at the club.
The Ireland three-quarter Jonathan Bell has also signed to play for the Saints next season, but the club's director of rugby Ian McGeechan has defended the influx of non-Englsih players.
McGeechan, the former Scotland and Lions coach, said: "It is no different than it was 20 years ago. If you have got players moving to England for jobs it would be crazy to deny them the chance to play rugby."Reuse content