For a long time now, Yahoo weather shows constantly incorrect temperature for Helsinki, Finland. Usually 5-10 celsius degrees lower than the actual numbers, especially in summer.

At the time of writing, Yahoo shows 16 °C in Helsinki, while the Finnish Meteorogical Institute reports 26,6 °C. It wouldn't matter much otherwise as you can choose a more reliable news outlet, but this is the source for the weather widget on Mac, which makes it really annoying.