digestion issue

I fed my boa's last night and now 18 hours later we are having a power outage due to high winds.

Can they continue to digest without their heat source and if so, for how long

Technically yes - the digestion process is accelerated by the effects of heat including faster enzymatic rates. Interestingly, snakes have actually been found to raise their own body temperature from 1-4C depending on the species during digestion.

Functionally, unfortunately, the answer is not so much. It depends on the temperature of their enclosures without the heat, but it's likely that they will not be able to digest at a safe rate. A regurge at best is likely if the temperature is too low for too long. If you have or can get any of the handwarmer packs, you can likely wrap them in a towel or similar until the surface is a safe temperature and place them under the enclosure as a temporary heat pad.

I ended up starting a generator and getting my boy's thru a 20 hour power outage. They seem fine and has been 36 hours since they ate and no regurgitation. Thank god.