Hi, pear trees normally flower in mid to late spring, but as you only planted it in march, it's upset the normal process, it's just decided to flower now because it has probably settled down enough to try and produce fruit, but it's far too late in the season, that and the changeable weather, has made the plant think it's spring, it should flower as normal next year, Derek.

I would remove any fruit that may form, though, to put the energy where it belongs: strong roots and branches.