Most of our native orchids grow throughout the summer and are dormant during the autumn and winter months and these can be repotted at anytime while they are dormant, a period of several months. Our winter green species, of which Pyramidal Orchids and Green Winged Orchids are two examples, are different in having a very short dormancy in late summer before growing leaves which will spend the winter flat against the ground waiting for spring. This means that repotting has to be clearly timed to avoid damaging the actively growing parts of the plant.
So if you have orchids in pots that you want to rehouse, now is a good time to do it, the winter dormant species have more or less stopped growing and the winter green species have not restarted growing yet. Grab your John Innes number 2 and enjoy the late summer sun.