A cars engine begins to overheat when the temperature rises above 220 F but even at 300 F the engine may be perfectly safe.
But if your engines temperature keeps climbing you need to pull over and allow the engine to cool off and check the coolant level.
A vehicles normal engine operating temperature is between 195 F to 220 F and when the vehicles engine temperature gauge goes above 220 F then it's getting to where it's overheating.
When it goes to 300 F or above then your engine is overheating and it should be shut off to avoid engine damage.
Some cars and vehicles don't have an actual temperature reading on the engine temperature gauge but instead they have markings for cold and hot on the edges of the gauge and a normal range in the middle.
The temperature should be running about middle ways of the gauge and if it climbs above that then the engine is overheating.
When your engine temperature gets too high you should pull over when it's safe to do so and shut the engine off to avoid engine damage.
Let the engine cool down for 30 minutes to an hour and then open the coolant cap and check for low coolant and if it has low coolant you need to add some.
I always carry extra coolant for myself and in case someone on the side of the road is low on coolant and needs some.
I don't charge anything to add some coolant to someone's car if they run low on coolant on the side of the road because it's not that costly.
But you should always carry an extra jug or two of coolant in case you need it.
If your car is still overheating or rapidly losing coolant then you should have the car towed to avoid damaging the engine any further.
Also turning on your heater to full blast can also help to cool the engine down as well when it's overheating.