The title is actually a joke. Marco always says The Netherlands receives two days of summer each year. And those days seem to be today and tomorrow.
The image is in Fahrenheit, though to be honest I have gotten used to telling the temperature in Celsius these days.
86F = 30C
71F = 21.5C
61F = 16C
All you really need to know is 20C = 68F. That can get you through most of the summer, anyway.
The one thing I haven’t quite mastered yet is the 24 hour clock. All clocks here are in military time, and even the tv shows are listed in military time. A 7:15PM show is listed as 19:15.
…Yes, shows can start at 15 after the hour, or 20 after the hour (etc). This is partially because there aren’t as many commercial breaks here (though the breaks they do have are longer), so it’s not as forced by advertisements. I do miss the more structured American method, though.