lots of good posts here! weather and other things do affect the bees temperament. also, if the hive is queenless, they will not be happy. no nectar/pollen coming in, cranky. many variables as to why a hive is snarky.
like g3 said bees are curious, and they will crawl wherever and explore, and they do find the crevice to get in the veil, up the sleeve, up the pants legs, etc....
but if you have bees nailing your veil or your hands/gloves when you open (use a smoker) this would indicate something else going on.
also, as iddee said, when we are new beeks, the bees can 'sense' so dress comfortably as you can to work them.
it's possible as chip mentioned that you have a queen that needs to be replaced.
i wear full gear, only because i am allergic, makes it hard when handling frames with gloves on, but i manage. whether i was allergic or not, i have always worn a veil and used the smoker. don't like the stings to the face.
i am sort of wondering about your queen. when you open the hive, do they immediately fly and start nailing your veil and hands?