Would anyone know reasons why my Beverley Sills iris did not bloom this year? It bloomed wonderfully last year but nothing this year. The plants are very healthy looking. It has been hotter than usual this year and very scant rain so I wonder if this could be a reason for non blooming.

Iris Don't necessarily bloom every year,some do ,some don't.There are some that take several years between bloom.
Of course it could be other reasons,weather related,too much shade, needs dividing(every several years),weed encroachment.
Since it looks healthy, it will probably bloom for you again next year.

Probably overcrowded and in need of dividing. Otherwise my Beverly Sills blooms magnificently every years.

My Beverly Sills doesn't bloom every year. My guess is that in your zone 2b your growing season may not be long enough for the rhizomes to mature enough to bloom every year. Just a guess.