Warm and dry conditions are expected to sweep across the Hunter during December, thanks to a little known weather event dubbed “SAM” by meteorologists.
It comes with temperatures expected to climb to 37 degrees at Maitland on Friday and a total fire ban declared for the region.
The Southern Annular Mode (SAM) will see a belt of high pressure systems move further north than usual, bringing below-average rainfall and and above-average temperatures to large parts of New South Wales.
“For December, we’re seeing quite a strong chance of above normal temperatures in the Hunter and that’s likely to continue into January,” Bureau of Meteorology climatologist Felicity Gamble said.
She said this time of year typically saw a run of humid, muggy days, but it was likely to be a dryer heat than usual because of the prevailing conditions.
“SAM will see that really dry air blown over the continent and into New South Wales,” she said.
Ms Gamble said SAM was on a “much shorter cycle” than other weather events like an El Nino or a La Nina, which can last for up to 12 months.
“We’d only expect to the see the influence for weeks or a couple of months before we come back to normal,” she said.
It comes off the back of a big wet during spring in the Upper Hunter, with Murrurundi recording its highest September rainfall in 143 years of records.
The town was drenched with 203 millimetres of rain, close to four times the average for the month.
It was also cooler than average in inland areas, with Scone experiencing its coldest average for spring nights in more than 20 years of records.
“That’s quite significant given we’ve had a long term warming trend,” Ms Gamble said.
But closer to the coast, it was warmer and dryer over spring. The average daytime temperature in Newcastle was 22.6 degrees, marginally above the long-term average of 22 degrees.
Norah Head had its highest average daytime spring temperatures in 20 years of records, with an average of a balmy 25.5 degrees.
Ms Gamble said inland areas were now at the highest risk heading into the bushfire season, because a wet spring followed by a dry spell could often prove a dangerous combination.
“You get a lot of growth in the spring and it only takes a few really hot days for it to dry out,” she said.
Thursday afternoon saw spectacular forks of lightening over Maitland as thunderstorms rolled through the Hunter but Ms Gamble said it could be a more subdued storm season than usual.