RCAHMW said the east and north-east of Wales has been very dry since mid-May, while much of west and south Wales stayed fairly damp and green.
However, the series of heatwaves in late June scorched off grasslands across Wales.
It revealed “monuments ranging from prehistoric long barrows and forts to Roman buildings and even First World War practice trenches,” they said.
The national archive for the Welsh historic environment has released photographs of Driver’s discoveries following flights from Haverfordwest and Caernarfon airport in June and July.
“This year has been pretty windy across Wales, so some of the longer trips to record cropmarks have made for challenging flying,” Driver said.
“Sometimes the cropmarks are so clear they jump out as we orbit the aircraft around to photograph them. But some parts of Wales are now so dry that the cropmarks can be faint and pretty hard to see.”
He added: “In these cases we digitally rebalance the colour bands of the image, really making the archaeology ‘pop’ and reveal previously hidden details – these images appear as black and white”.