I live in foothills of a lower range of hills (European Jura), and it has numerous effects. The air is normally blowing down the mountains towards us in the evening (katabatic wind), so it doesn't matter how hot the day was, evenings are pleasantly cool and night gets colder than expected. This wind also cools hot surfaces pretty effectively.

Even just entering a dense natural forest during the day, one can sense drop in temperature around 3-4C during summer, and increase in humidity during dry periods.