It's autumn and temperatures are still soaring across many parts of New South Wales.

Over the past week, a new record was set for the hottest Sydney day in April, and Dubbo recorded its longest stretch of days above 30 degrees, according to the Bureau of Meteorology.

Sydney also saw its longest running hot spell for April, with nine consecutive days of temperatures reaching 25C or above.

The temperature on Observatory Hill on Monday was 35.4C, beating last year's record of 34.2C, and although it might not sound like a lot, one degree of difference is quite significant, meteorologists say.

By 2:00pm today, temperatures on Observatory Hill hit 34.2C and Sydney Airport was only slightly higher at 34.8C. In the west, Penrith hit 34.9C and Campbelltown 34.1C.

The higher April temperatures are making for more idyllic beach days, but are having an effect on the world around us with plants "confused", animals sluggish and delays in hazard burning.

Manchurian pear trees are so confused by the unseasonably hot weather that they are flowering in autumn instead of spring. ( Supplied )

Plants 'think it's spring'

Crepe myrtles, Manchurian pear trees, bougainvilleas, magnolias and frangipanis should be shedding their leaves.

But Tim Pickles, from Tim's Garden Centre in Campbelltown, said he had seen them all flower again due to a bout of rain in the area.

"The trees are just very confused at the moment — they think it's spring again," he said.

And winter seedlings are struggling too.

Tim Pickles from Tim's Garden Centre in Campbelltown says the hot weather is delaying broccoli growth. ( Supplied )

"I've planted cabbage seedlings and broccoli, they like the colder weather, and they're just sitting there sulking," he said.

"Winter vegetables are just going to sit there and sulk until temperatures cool down."

He added mango tree sales have spiked, with more tropical trees thriving in the region.

"We're selling 100 mango trees a year — in Campbelltown!

"Thirty years ago if someone said 'I want to grow a mango tree', I would have said they will die from frost in winter, but now we are selling so many."

Sprinklers keep penguins cool

Some animals seem to be more resilient, albeit a little more sluggish.

"With our seals, they're not as hungry and a bit more lethargic on a warmer day," Andrew Irvine from the Marine Mammal Department at Taronga Conservation Society said.

But he said they were pretty good at mitigating the heat.

"Seals when they raise their flippers into the breeze, they're cooling down," he said.

"They use counter-current heat exchange where the warmest blood is going past the coolest blood so there's always an exchange of temperature, we use it in refrigeration.

"So [it's] a remarkable adaptation to cope with different temperatures."

It's easy to regulate temperatures for penguins, Taronga zoo says. ( Rick Stevens: AAP, file )

Seals also immerse themselves in rock pools to help cool off when the mercury soars.

Mr Irvine said it was easy to regulate the air temperature for animals like the little penguins.

"With these elevated temperatures, by putting the sprinklers on we can bring the temperatures down, so we tend to react to the hotter day before the animals do."

He said the penguins had finished their moult and were not due to breed until August or September.

"If we've got sustained hot weather around breeding and moulting, that is more of a concern, but those spikes we can manage fairly well."

Increased bushfire risk 'unusual'

The bushfire season has been extended and hazard reduction burns delayed due to the hot temperatures. ( ABC News: Elena de Bruijne )

The hot April has meant an extended bushfire season and delays in hazard reduction burning, according to the New South Wales Rural Fire Service.

RFS spokesman Inspector Ben Shepherd said there had been more heightened fire danger ratings than normal for autumn.

"To see places like Sydney especially, move into the 'severe fire danger' range is unusual for this time of the year," he said.

Some parts of the Greater Sydney Metropolitan area also tipped into "severe fire danger" level, and an number of areas amped up to "very high" in the Greater Hunter and Southern Ranges.

Surf livesavers are seeing more people on the beaches this autumn.

And there's been no respite for lifesavers across the state.

Liam Howitt from Surf Lifesaving New South Wales said it looked like they were heading towards one of their busiest Aprils on record.

"In many ways, it's been like summer and certainly keeping our lifesavers busy … Certainly with the number of rescues and first aid treatment," he said.

But Bruce Hopkins, head lifeguard Bondi Beach said it had mostly been business-as-usual at one of Australia's busiest beaches.

"No need to put more people on, we've had probably a lot more people hanging around into April than what we usually do, but the impact hasn't been significant."

Farmers adapting

Dr Zvi Hochman from CSIRO Agriculture and Food said wheat farmers were sowing their yields earlier to avoid losing crops.

"In the last 28 years, the trend has been a stagnant yield," Dr Hochman said.

Previously, wheat yields increased year by year in a 90-year trend before stagnation.

While yield potential has gone down, "the only reason we're not seeing lower yields is because of the adaptations farmers have made to cope with those changes," he said.

"Farmers are sowing their wheat earlier to avoid that hot and dry period in spring which is becoming more and more common in some but not all growing areas."