Extreme heat palpations or afib ?

If you feel some thumps every few beats, it is called 'premature atrial contractions', or PACs. Could also be PVCs, premature ventricular contractions. Just feel your carotid pulse, gently, don't press hard, try to relax, and feel for the extra strong pulses. They are generally benign, but they can be intrusive, and of course worrying. It is only when you get several thousand of them in a day (your heart beats about 85K times each day) that they have an excessive 'burden' as it is called and an electrophysiologist would probably offer to do a catheter ablation for you.

If you feel your wrist or carotid pulse, again, just enough pressure to get a feel for the pulse, and you don't feel much of anything or it's erratic, that is probably atrial fibrillation. Again, generally benign in its earliest stages and when it comes and goes on its own. It is when your heart rate is measured at 100 or more BPM and it goes on for 24 hours that you should go to Emerg and get it looked at.

This is almost certainly NOT a lethal arrhythmia, but you should still get seen by a nurse or a doctor very soon if the arrhythmia continues without a break....24 hours or more, get to Emerg.