Water boils at 212F, period.
Okay, that's a half-truth. It's true for pure water at sea level. Higher elevation means lower boiling point (at 3500' where I live, it's about 209F I think). Conversely, dissolving stuff - like sugars - in water generally raises the boiling point. But when it boils, it doesn't really get any hotter except maybe in some local spots within the vessel.
The key isn't temperature, it's the boil itself. Is it rolling? Percolating doesn't count. It should be turning itself over pretty well. Here's an example:
. . . though if you're low on head space in your boil kettle that might be a bit scary for you. The real danger is at the beginning when you get the hot break, as the foam really piles up until it starts to roll and really settle in.
Anyway, don't watch the thermometer. It's not a magic temperature, it's a function of how vigorously the liquid is boiling. In Denver, that might happen at 208F, in Seattle that might be 211F.