Dust is the #1 killer of fan bearings. The power supply, case fan, or CPU fan(s) could all be at risk in a dusty environment. If you have pets or dry skin/scalp it is very likely you haven't been keeping the guts of the machine safe from dust.
If it actually is the temperature in the room, you may have a fan casing that warps out of shape when the CPU temperature increases. I had one that did that. Took forever to fogure it out. Eventually the fan started locking up completely, but it wasn't a bearing issue...except that the bearings were getting pinched by the casing. You could let the thing cool down, take the fan off, boot up and the fan would never have an issue. Put it in place and run it a while and the noise/locking invariably happened.
The path to peace is one of change, grasshopper. Change the fan.