Travelers at that altitude can expect a comfortable pressure of one Earth atmosphere, and their thermometers will register a balmy 59 degrees Fahrenheit, or about 15 degrees Celsius, not too shabby.
When I take the thermometer out of the water, the temperature is going to go down, but it's not going to go down as much because the water evaporating off the thermometer doesn't have any place to go.
Shortly after, the mercury in the thermometer would descend below freezing and stay there until April or May, when the snow would begin to melt and the rivers would rush with the clear turquoise of super-oxygenated ice.
So this shows the global average surface temperature reconstruction from all the thermometers on the planet and proxies going back to 1880 to the present day.