Its not the next couple of cold (frost ?) nights but the chance of late frosts in say 2 or 3 weeks time when the tops are emerging - knocks them back a bit.
Early potatoes aren't necessarily named for early planting but for the shorter length to harvest.
Quick yay or nay - Plant early potatoes in pots today with a couple of -2 nights ahead?
Never done pots before so not really sure.