You check oil level after the engine has been shut down for a few hours and oil can drain back into the sump .
I have a temperature indicating dipstick, I realize that I am at the high extreme due to the average temps here in the northern Sonoran desert .
But when I lived in the Chicago area I would normally see temps in the 240 F. (116 C) area .
I'm not sure how accurate the indication is, due to I'm sure the dipstick isn't sitting in oil, it's just getting 'splashed' by oil being thrown about in the crankcase .
In our typical summer temps here in the 110-115 F (43-46 C.), the normal oil temp is 275 F. (135 C) and this is with an oil cooler installed.
If I get up to highway speeds, I'm speed limited, to keep the oil temp below 300 F (150 C).