The Volts resumed yesterday on 162 for three with Jesse Ryder on 52 and Ryan Duffy on 12 and looking to push on past Wellington's first-innings total of 297.
But with more time lost during the match, Otago opted to declare at 251 for eight. Wellington reached 70 for one when poor weather forced the players from the field again.
The Firebirds lead by 116 runs with nine second-innings wickets in hand.
Unless there is dramatic collapse this morning, the match will most likely end in a draw.
Earlier, Ryder added a further six runs to his overnight total and Duffy (20) could not get re-established at the crease either.
Derek de Boorder was bowled for a duck but a valuable 26 from Mark Craig helped Otago get past 250 and bank a batting bonus point.
Matt McEwan took three for 70 and the experienced pair of Brent Arnel and Andy McKay picked up two wickets apiece.
In Whangarei, Northern Districts beat Central Districts by 43 runs in a tense finish to a keenly contested fixture.
Set 348 for victory, Central resumed day four yesterday on 23 for one.
Greg Hay made 98 and Will Young (56) and Kruger van Wyk (62) notched half-centuries as well.
But spinners Anton Devcich (a career-best four for 46) and Mitchell Santner (three for 70) grabbed seven wickets between them to help secure the win which has lifted Northern into first place with 66 points from six games.
At Colin Maiden Park in Aucland, Canterbury posted 340 in reply to Auckland's first-innings total of 294.
Henry Nicholls (102) scored his second first-class century and Neil Broom (46) and Matt Henry (39) were the other major contributors.
At stumps on day two, Auckland was 29 without loss and trails Canterbury by 17 runs in what promises to be a fascinating match.
