In Moscow the average daily high for July is 24°C (75°F), so I would guess few people there have air conditioning. That summer had to be brutal. (I don't have A/C where I live, and would rarely need it anyway, which is good because I hate being in an air-conditioned building all day. I lived in Tempe, Arizona for a year and a half, and even with A/C the summers there are tough, with high temps around 115°F. You go outside at 10 at night and it's still 103 or so. One day it hit 122°F and they closed the Phoenix airport because planes aren't tested above 120°F. On the other hand, November through April there is idyllic.)
Grumm reviews that summer's blocking ridge in central Russia, but doesn't go into attribution. It's interesting reading.
By the way, wheat prices still haven't come down for that heat-wave induced spike. (Last year I estimated this rise cost the world $67B per year, and the U.S. $2.1B per year.)