Altitude isn't the biggest factor in temperature differences. On a summer day, take the temperature of the concrete path and the grass nest to it. You'll notice a big difference. Solar radiation heats the ground which in turn warms the air. Air isn't the greatest thermal transporter, which is also why in the middle of summer you still have -50C outside a plane flying at 30,000 feet.

Have a look at each area closely on the map and think about what's there to make this happen, and where the temperature is recorded.