relative humidity and altitude typically play more into the need to rejet than does moderate temperature change. I know all 3 are interrelated, but a lot of people tend to look only at one and draw conclusions based on a single aspect. A barometer is your best friend for jetting. With my bird in the summer, i can start at the track in the morning and run into the night and not need to rejet if i start a little fat. helps that Island dragway is 15 minutes away with only 100 foot elevation drop. if i go to E-town or Atco, lower altitude and it needs more. Maple Grove runs the same setup as Island. Other times of the year, then it's just a guessing game throughout the day anticipating how much faster the car will go--i'll come down nearly a 1/2 to 3/4 second in my ETs sometimes. in the spring or fall, at any of the tracks it'll need at least one, possibly two rejets because the change in temps and air density is large enough to warrant it.
setting up the buggy here at home then racing it 800 feet higher, 30 miles north in a totally different geographical terrain with a different weather system is a real head scratcher. add to it that you're not allowed to do any prerunning/driving of race vehicles on the property other than firing up the engine to warm it up/work on it on trailer or campsite and it becomes a total crapshoot.
If you've every heard the term "cold crisp air" that's the point where you can have colder air (below 32 degrees) that is less dense because it's very dry air. around 33-35+ degrees, you have air that you can nearly drink and you know snow or rain is coming. big difference between the two which will actually require the opposite jetting than just basing it on temp ... I prefer to jet at this time of year to get a baseline setup that's about as rich as i'll ever need.
good morning .... just rambling ...
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