Once you get down to changes for weather and location you are into fine-tuning, this requires experimentation and good note taking. At this point the fine-tuning is as individual as the rifle its self what works with one may not work with another rifle of the same make and caliber. Keep careful notes by location and temperature. If you are shooting black I would add humidity to the mix. This all comes under the heading of learning your rifle.

40 Rod

When I  shot HP Silhouette at Raton with a 7mm08 sight settings were a few moa different than in Virginia at Sea Level.  This due to thinner air.

As far as changing loads due to ambient temperature. With 32/40's that are  just going sub sonic at 200 yards cold day takes more clicks on the powder measure. It's real obvious when holes on the paper look oblong due to velocity lower than on warm days.

Does a "sweet spot" powder charge change according to weather ? I doubt if you could tell the difference with a rifle fired outdoors, hand held rested under normal match rules.

Small stuff takes a enclosed tunnel and mechanical rest to sort out.  Charlie Dell determined he could not test small load changes outdoors with a hand held rifle and come to any conclusions. He  built a enclosed tunnel out of his basement shop with return to battery rail gun fixed point of impact.  That sorted out the good from the not so good.  Shoot off a bench outdoors little changes in temperature can’t be proven is my opinion.

Boats

[quote author=1A3F383E0F1C3F253923500 So typicaly when the temp is low the moisture is up 
JLouis [/quote]

Generally cold air holds less moisture and geographic locations experience drier air during their cool or cold season.