sudden cold spell--what to do with musk melons?

My musk melons were coming along nicely during the summer heat. We had more than a week of 30C+ temps and though I despise heat, my musk melons seemed to appreciate it. Unfortunately, all good things must come to an end, and the temps suddenly fell to below 20C. It doesn't look like it will warm up to much beyond 20C anytime soon.
AFAIK, musk melons grow best in hot weather. Now that I no longer have hot weather, what is the prognosis for my little melons? Is there anything I can do to help them continue to grow and then ripen? They aren't that big, yet. The largest one is about 4 or 5 inches long and maybe 3-ish inches in diameter so they still have a ways to go.
I'm in Zone 3a, by US standards, 2b by Canadian standards (I think).
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