38F = 3½C
57F = 14C
Not sure why you used Farenheit, but I live in the north too and it's colder and warmer than that. Currently 22C (61F) here in rainy Manchester.
First, I'm not in Manchester, considerably more northern, so why try to compare?
Secondly, Manchester's average temperature in August is close to 16C (https://en.wikipedia.org/wiki/Manchester#Climate).
Thirdly what is strange about the temperature on a given day being higher than the average?
People from Europe likely already have a vague idea of what the temp is like in northern parts of it, and 45% of HN is from US according to https://news.ycombinator.com/item?id=3298905