From memory, 1980 summer was pretty average around these parts.
i was playing a bit of cricket at the time and remember a few weekend games being rained off.
it was probably similar to this year in fact with a few decent days followed by a wet spell although I don't remember much in the way of hot conditions.
the others I agree being as you said, 83 and 84 were belters, 83 with a hot July and for us was also a cracking hay making period, other than the sunburn I got one weekend, 84 for its dry, drought conditions.
then it was downhill into a few years of poor conditions and I don't remember much in the way of memorable heat until 1989 and 1990