Cold temperature

No don't harvest, until they're ready. They will cope with temperature changes, it might even help them finish up!

They look nice It is the roots that suffer before the foliage when it is cold The leaves and buds can survive frozen temperatures for a while It's the wet and damp that causes mold problems that is more an issue Plants growing directly in the ground are most likely to suffer because the ground temperature is very cold the roots can get damaged plants in pots outside can be raised up off the frozen ground to protect the roots I think they will survive a night or two without any problems If the ground is very cold you can water them with warm water and a wetting agent find something to cover them to stop them getting wet/damp or if the cold continues

If you're capable of covering them with a tarp or something, they should still survive -2C for one night. If it looks like the night temps are dropping now longterm and continue going below zero, I'd probably just harvest then because covering them often with a tarp especially if it's not followed by a sunny day will risk rot and mold issues.

Weed plants are very hardy. Just watch for bud rot and remove affected areas. My girls already had 3 frosts and my northern lights are still going strong...My buddy (rip) had a plant he grew up until xmas time. I watched this plant kick ice off her flowers when the sun hit them...

Chop them same morning after frost, aka drag as long as you can .... They needed a month for developing, but ... Even if it will be harsh , untasty after you dry and cure - you can anyway do bubble hash or butter for eatables ...