How much does temperature and/or humidity change affect point of impact?

[NYH1]

I was at the range today shooting my Remington 700 308 Win. (and a few other non-precision hunting rifles). It shot great, nice sub-MOA groups as always. However, my groups were all .5" to .75" higher then usual.

I last adjusted my zero in mid June when I switched from FGMM 168 gr. to FGMM 175 gr. It was around 65° with no real noticeable humidity or dew point (not that humidity/dew points are too noticeable with 65° temps.). Today it was about 85° with 68% humidity with dew points in the upper 50's with no wind to speak of.

Would the extra 20 degrees with a little more humidity and higher dew points make the rifle shoot a tad higher?

Thanks, NYH1.