It is a series of data points, which doesn't prove anything.

You might however suggest the hypothesis that the letter u prevents rain. The scientific test of your hypothesis would be whether it rains in February, June or July. If it doesn't, then you are on the track of something interesting. A lot of science is about investigating apparent anomalies: why does it sometimes rain in March? Anything to do with leap years? What is the complete annual rainfall distribution? Any other "sometimes"? Time for some experimental investigation: if we taught the population to speak French, pleuvrait-il en janvier?

Scientific proof is pretty much the inverse of mathematical proof. In maths, QED means absolutely and always, but scientific proof is further from the Latin probare (certify, testify...) and closer to the German Prufung (test, examination). Scientific knowledge is the residue of explanatory and predictive hypotheses that have not been disproved.