Perth at that time of the year can either be very good or absolutely rotten. Its late spring through late summer and can be very hot and unsettled. Early morning is a good time to get out, especially if there is no easterly wind blowing, but the afternoons can get VERY blowy making for some rough flying.
I actually enjoy this time of year for flying in Perth. If it is not raining (and according to everyone we're heading for a drought
), then the conditions are excellent. Smooth, clear sky. This can hold right through to the end of August / beginning of September.
Hope this helps and if you would like some more info, drop me a line.
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