OK, so it has to be at least 65° or so for epoxy to cure properly.

Let's just say you spray it and it's borderline, perhaps a little colder, and the epoxy goes dormant shortly after you spray it, or at the very least just sits there and either doesn't cure or cures very slowly. But then a little while after spraying it, the temp goes up into the acceptable range. Is it too late or will the epoxy begin to cure at that point? If it is possible for the epoxy to begin to cure after having been sprayed in a colder than ideal temp, how much time do you have after spraying for the temp to go up before the epoxy simply dries and becomes worthless?

The reason I ask is, I need to epoxy my trunk repair, but today is in the mid-60s and raining, not ideal . It's supposed to be warmer tomorrow and warmer still on Sat and Sun. However, I'm leaving early in the morning tomorrow and won't be back until Sunday evening. Monday is supposed to be nice but I have to get ready for a road trip, lasting 6 weeks. I don't want to let my bare metal and filler work to sit exposed for that long. I was thinking shoot it tonight (low 65), and let it cure when the temp goes up tomorrow (around 70). Possible?

The temperature of the panel, the metal itself, is more critical than the ambient air temperature. Do you have a heater of some kind? Anything to rid the air of humidty will help.
Epoxy, once catalyzed is going harden without any problems down to about 55 degrees and if you're going to leave it for weeks, You'll be fine. It will be there when you return, hard as a rock ;)

Could you go to a rental and get a couple of electric heaters, warm it up good, then shut them down and spray.

You need to have that metal temp steady at around 60 degrees for a few hours after spraying epoxy.

Epoxy unlike urethane will go dormant, it stays dormant for a certain time frame it wont fully cure. I dont recall what SPI says about their epoxy as for time wise, but drop Barry an email.

Thanks guys. It was 60+ in there for sure.

Hmmm, six weeks, thats my window Brad, to get the jump on him.:yes: