Stephen Peters' unbeaten 74 allied with Rob Newton's 40 not out put Northamptonshire in a good position in the LV= County Championship Division Two home match against Yorkshire.
Just 57.4 overs of play were possible at Wantage Road, where Northamptonshire closed on 175 for three.
They will take to the field on Friday just 74 runs behind Yorkshire's first-innings total.
Meanwhile, a final wicket partnership between Dean Cosker and Huw Waters sparked a dramatic Glamorgan recovery on the second day of their encounter against Gloucestershire at Swansea.
After resuming the day in real trouble at 64 for six in their first innings Cosker and Waters added 83 runs to take Glamorgan to 208 all out. In reply, Gloucestershire struggled and finished on 91 for seven, 117 adrift.
Openers Tom Westley and Jaik Mickleburgh both completed their centuries for Essex against Leicestershire at Chelmsford.
Mickleburgh was the first to reach three figures and went to make 126, with Westley one run less as Essex declared on 434 for three, while Leicestershire closed on 32 for two - David Masters taking both wickets against his former county.
Kent reached 238 for eight after being put in to bat on day one of their clash at Derbyshire.
- Huw Waters
- Dean Cosker