Your climate is similar to mine - they should be OK but might take longer - 3 days. If they take much longer than that you might want to consider culling them - not sure, never experienced it.
I currently have an out side spawn (not planned). My water is unstable so I'm on a break from breeding. These are siblings I missed moving (didn't feed them for at least 3 weeks - but I know some tubifex are in there). I never took the tub and plants (crammed with plants) apart. Then I see 5mm fry. I'm going to try OFL's method of leaving both male and female in. I have never seen any eggs but I'm guessing they're spawning every few weeks (I noticed fry because I was watching them spawn). Now the second batch is about 5mm (about 10 days). I'm guessing there are less than 20.
BTW I previously took out 2 5mm fry and left at least one (about) 3 day old fry (from free swimming). Though the big fry wasn't eating the small fry (I often saw them side by side), I didn't want to chance the latest batch. Mom and dad aren't eating them neither. The male is a bad daddy - no nest, no egg rearing .... but, unbelievably I have fry. Now I'm pouring a cup of daphnia in the tub weekly. No rain, no water changes (only topping every 2 weeks). But somehow they're breeding. I could never deliberately do this.
Sorry for getting off topic. Just thought I'd share this one outside spawn (all of my bettas are outside but under a roof - only 5 tubs get direct sun and rain)