Driving home today probably 40deg out. Sitting in traffic noticed gauge quickly climbing almost to red zone, I gave it a little gas and it came down. Once I got moving I noticed the gauge would climb up to around 220 them drop instantly to 160 and continue doing this constantly. Seemed to be dropping when I accelerated too.

Car has been fine until today no cooling issues in fact rarely above 220 ever! Never behaved like this before.

Would low coolant levels cause erratic behaviour like this?

 

That sounds like an air bubble.

do you have an electric fan or clutch/mechanical fan?

Low coolant would cause the car to run hot, as there isn't enough coolant to do the job properly.