My cereus peruvianis has some little brown patches near the spines which just popped up, I'm not sure what they could be

looks like sunburn?
i know 44+ degrees will do that.
or did it appear more recently like in the past few days?

No it might have been the last couple of weeks, this one is around the side of the house at the moment, sunburn sounds likely with the weather we've been having. Poor thing

yeah.
is it potted or in the ground?
if it's the former try to move it to a more shaded location.
they are astonishingly hardy though.
pretty darn hard to kill actually lol.

Potted, I have already brought it around to a shadier spot so I can keep an eye on it (and it's about to flower)
Thanks Lewis

yep, looks like sunburn to me too. Minor scars, no sweat.

Summer is over