There are four diffrent lines in this diagram, it shows the average tempearatures for each month in one year. Each of the four cities were having the highest temperatures during summer time, and the lowest temperatures during winter time.
In these four lines, Tokyo has the highest average temperatures in one year compared with other three cities, for the line of Tokyo, the lowest temperature in January is nearest ten degree, and the highest temperature in Augest is near thirty degree. Compare with New York and Tokyo, Berlin and London have the lowest average temperature in one year, the lowest temperature in Berlin is in January, it is under zero degree, it also the lowest tempearture amount these four cities, for the highest temperature in a year, Berlin and London are the lowest compara with other two cities, there are only nearst twenty degree, but Tokyo and New York are above twenty degree. In these four lines, the unique one is New York, New York has very low temperature during winter time, but the summer temperature is very high.
In conclusion, Tokyo has the highest average temperature, but London and Berlin have the lowest average temperatures, New York is the unique one, winter is very cold, and the summer is very hot, the temperature changes are very obvious.