The Scotstoun side's record-breaking run of six straight PRO12 wins came to an end against Leinster on a stormy night in Glasgow and Townsend wants to see his team get back to winning ways against Munster.
Speaking to www.glasgowwarriors.org, Townsend said: "We know how tough it's going to be at Thomond Park, they've only been beaten there once in the past twelve months.
"They are a more expansive side than they once were and they will be looking to extend that fantastic home record. We've got to able to match them physically if we are to have a chance of winning over there.
"I'm delighted that we can put out a strong side this weekend though and, with a number of our Scotland boys back in the team, we'll be doing everything we can to come back from Ireland with that elusive positive result."
As well as Weir returning to the stand-off berth, Henry Pyrgos, who made his debut during the November international series, returns to scrum-half.
Stuart Hogg starts in the centre alongside Peter Horne, with Peter Murchie filling the full-back position. Sean Lamont is also restored to the line up on his return from Scotland duty with DTH van der Merwe on the opposite wing.
In the pack, John Barclay replaces Chris Fusaro at open-side flanker with Fusaro having picked up a knock against Leinster. Barclay teams up with Rob Harley and Ryan Wilson in an all-action back row.
Warriors skipper Al Kellock is also restored, partnering Tim Swinson in the boiler room with Ryan Grant, Dougie Hall and Mike Cusack at the sharp end of a heavyweight pack.
Townsend said: "We've got a huge amount of competition for places in the squad and it leaves me with difficult, but ultimately good decisions to have to make.
"It's great to have Duncan back in the team, as he's been itching to play again since returning to full fitness after an unfortunate training injury a couple of months ago."
"Moving Stuart to 13 alongside Peter Horne will allow us to have other options at first receiver and gives us another dimension to our attacking threat."
"Gordon Reid has done tremendously well for us over the past few weeks and he was unlucky to miss out on first Scotland cap last week but Ryan is probably the outstanding loose-head prop in the country right now and it's great he's fit and ready to play."
"It's also great to be able to call on Dougie (Hall), John (Barclay) and Al (Kellock) who can bring to bear all their experience on what should be an absorbing contest."
GLASGOW WARRIORS TEAM TO PLAY MUNSTER IN THE RABODIRECT PRO12, THOMOND PARK, SATURDAY 1 DECEMBER, KICK OFF 7.45pm.
15. Peter Murchie
14. Sean Lamont
13. Stuart Hogg
12. Peter Horne
11. DTH Van Der Merwe
10. Duncan Weir
9. Henry Pyrgos
1. Ryan Grant
2. Dougie Hall
3. Mike Cusack
4. Tim Swinson
5. Al Kellock (Capt)
6. Rob Harley
7. John Barclay
8. Ryan Wilson
16. Pat MacArthur
17. Moray Low
18. Gordon Reid
19. Josh Strauss
20. James Eddie
21. Niko Matawalu
22. Scott Wight
23. Byron McGuigan
Not available for selection due to injury: Chris Cusiter (shoulder), Alex Dunbar (ankle), Ofa Fainga'anuku (shoulder), Chris Fusaro (groin), Ed Kalman (back), Rory Lamont (leg), Angus MacDonald (neck), Graeme Morrison (knee), Jon Welsh (shoulder).