Occy
I can't recall that happening to me. As for the temperature, I enter the average ISA deviation between the CRZ level (as in PROG 2/4), halfway through the descent from the OFP and destination. Just a rough estimate, and usually only if the ISA deviation is warmer. Better be slightly low than high. The effect of temperature is not as big as barometric setting. FMC U14 should bring some improvements about temperature correction.
If during descent you notice that the wind is different from the forecasted descent winds, you can always recycle the WPT on top and VNAV will recalculate the descent profile with the actual wind.