Wouldn't it be wonderful if we could rely on the weather, it would take all these difficult decisions away from us!
May & September - can be lovely in PP but of course the weather is unpredictable during these months and the local people always refer to September as the rainy month (although I spent 2 weeks there this year and not a spot of rain). May is normally lovely, we have had superb weather in past years but this year was the exception, raining almost every day.
January, February, March & April - are also beautiful, with the natural beauty of PP able to be seen without the distractions of bars, shops, sunbeds & parasols on the front. There are, however, still some shops bars and restaurants open in the town of Puerto Pollensa. The bars, shops etc. on the front start re-opening gradually about the end of February. The sea would be cold though at this time of year if you have children. The sun still shines in January & February and if you can find a nice sheltered spot you can still take a tan home. We went in April this year and had lovely weather.
Note: the sight of the almond blossom in January is spectacular.
June, July & August

- you can usually guarantee the sun but it gets very hot, sometimes too hot to go out. Air-con is needed to get a good nights sleep. The bars & restaurants are busy and there is plenty of hustle and bustle. The buses are on the summer timetable so run very frequently to the old town and up and down to Cae'n Picafort, also every hour to Palma with other buses running daily to other destinations.
October, November - We were in PP last year in October and had good weather with plenty of warm sunshine until a storm (which only lasted a day) arrived, the heavens opened (I have never seen rain so heavy) it was reported to be a mini hurricane. We are going this year in November (we are counting the days

) so cannot comment yet, but watch this space.
December - Never been, but would love to experience Christmas amd New Year in our favourite place. Next year perhaps.
We cannot guarantee the weather anywhere but Puerto Pollensa would always be better than Britain and although there are short days in the winter months they are not dull, miserable and gloomy. My favourite time of year though has to be Spring (April, May) when everywhere is fresh and clean and nature is looking it's best