They beat rivals Northfields 3-0 taking the sets 15-9, and 15-12 with a fine performance.
Coach Tom O'Jasso said: "We were always in control and the scoreline makes it look a lot closer than it actually was.
"It was good to finish the season with an important win and now we have a few friendly tournaments before starting in the league again in October".
On Saturday Riga were involved in a friendly tournament at Cathorpe near Rugby.
They reached the semi-final but were knocked out by Sefton of Liverpool.
In the final Coventry District beat Sefton to take the title while the ladies' champions were West German touring side Cologne who beat Birmingham Athletic Institute.
