The home side enjoyed the better of what action there was, but more too much Welsh rain means the game is likely to end in a draw.
Figures of four for 18 from Andrew Salter helped Glamorgan dismiss Northants for 215, although the home county only needed to take nine wickets with Gareth Berg absent hurt.
Glamorgan’s reply reached 52 for two when the second rain shower of the day delivered a fatal blow to the afternoon’s action.
Rain meant only 44.5 overs were possible on day one and day two started half an hour late, but the County saw Berg suffer an ankle injury warming up.
It was a big blow to the visitors.
Overnight batsman Charlie Thurston and Saif Zaib resumed with the score 128 for four and while both played and missed on occasion, the pair were relatively untroubled.
Zaib went to 50 from 92 balls, but both batsmen were then dismissed in quick succession.
First, Thurston was caught by Billy Root from the bowling of Michael Hogan.
Then, Zaib drove Salter to Marnus Labuschagne at short cover for 50.
Salter also dismissed Simon Kerrigan for a 22-ball duck, caught by Timm van der Gugten at mid-on.
Ben Sanderson went lbw to Salter with Northants 197 for eight at lunch, and Salter’s fifth ended the innings nine down after the break.
Jack White was caught by Van der Gugten and Berg was unable to bat.
Glamorgan opener Joe Cooke survived a run out scare but was then caught at first slip by Northants skipper Ricardo Vasconcelos as Sanderson got one to move away off the seam.
Vasconcelos then grabbed David Lloyd too with Luke Procter the bowler this time.
A sharp downpour forced the players from the field at half past three with Glamorgan 48 for two and an early tea was taken.
Labuschagne and Root returned to the field but were able to add only four more runs before more wet weather intervened.
The second shower of the day was far heavier than the first and play was abandoned at five past five.
Labuschagne (17 not out) and Root (6no) will restart on Tuesday morning, but Glamorgan will have to bypass their opponents quickly if they are to try and force a win.
Australian Test star Labuschagne – who didn’t look totally convincing with a couple of boundaries to third man – will hold the key to their fortunes.