In America the Rankine and Fahrenheit scales are appropriate.
Everywhere else in the world it is Kelvin and Celsius.
On a freezing cold day the temperature may be about 492 degrees Rankine (32F), on a nice warm day 542 degrees Rankine (82F) say fifty degrees hotter or very roughly ten percent.
So the ambient temperature does not make as big a difference as you might expect to compression readings. But it will make some difference.
The problem with all of this is that you cannot reliably predict from theory, what all the variables and unknowns are going to produce in the way of an actual cranking pressure reading. Some of the cheaper gauges are not that accurate either.
You just need to know from experience if what you are reading on your compression gauge is fairly normal for that particular type of engine, tested in the way you normally do compression testing..
In a way it is a bit like leak down testing.
You measure a fresh built engine. You measure again once the engine has been fired and broken in. And you measure again after some high mileage. The actual figures don't matter that much, but what you are looking for are changes, and cylinder to cylinder variations that can indicate problems.