The long weekend will bring beach weather and the start of daylight saving, but the outlook for the rest of the year is wetter than usual.

The signs of spring are everywhere: waratahs and wattle in bloom, surf lifesavers on patrol at beaches, swooping magpies and a frenzy of insect life.

In this long-exposure photo, you can see the flight pattern of seagulls as they gorge themselves on moths.

Dr Andrew Mitchell, an entomologist at the Australian Museum specialising in butterflies and moths, said there were 22,000 described species of moth in Australia and probably about 1000 in Sydney alone. Caterpillars hatched in late winter or early spring and many species would be emerging from their pupal stage now.

“It’s the normal spring breakout,” Mitchell said. “But the numbers of insects and moths are heading down and any sort of seasonal surge in numbers is pretty muted compared with years ago. I remember as a kid going on road trips and having to stop at a servo and wash the windscreen every 100ks because it was just full of moths.”

Mitchell said Australia did not have good data, and people often only paid attention to charismatic species such as bogong moths and Christmas beetles.

However, he said there were solid long-term data sets in Europe because of a strong tradition of citizen science. This showed, for some species, an 80 per cent decline in insect populations mainly because of habitat loss, but also pesticides drifting from farms, and climate change.

The weather bureau predicts a surge of hot weather across NSW for the October long weekend – Sydney will see tops of 27-28 degrees across Saturday, Sunday and the public holiday Monday.