The temperature plummeted to a low of -6°C in the sleepy Irish hamlet of Templemore during Colin O'Riordan's return visit over the off-season.

The freezing conditions were more than enough to force the former resident to rug up for the entirety of his stay and wipe away what was left of the defender's Sydney tan.

On Monday, Sydney woke from a restless night's sleep after sweating through what was a sweltering summer's day with the mercury reaching 47°C in parts.

The morning threw up sticky and humid conditions, challenging for all Sydneysiders but especially the Sydney Swans playing group as they tackled their first session of the new year at Weigall Playing Fields.

And that extra bit challenging for O'Riordan, who only arrived back in Sydney a few days ago.

"It's a 40-degree difference," O'Riordan pointed out following the session.

"It's pretty tough at the start but once you get back into it and get used to it again, you acclimatise pretty quickly.

"But, yeah, there's a bit of a difference alright."

O'Riordan, luckily, as with the rest of his teammates, had an individualised running and fitness program to keep himself honest during the Christmas and New Year break.

The 22-year-old admitted though, no matter how much hard work is done over the break, little can be done to simulate the intensity and hard yakka of training.

"I don’t think you can ever get prepared for the first session back," he said.

"Obviously, doing the running program over the break helps an awful lot.

"Few boys were puffing… but most of them did it well.

"A few always look better than others."

O'Riordan, who's halfway through his third pre-season training, says the hard work is only just beginning now the new year has arrived.

At the time this story airs there will be only 53 days before the Sydney Swans take on Brisbane in the first of two JLT Community Series matches.

And only 75 days until the Swans' home-and-away season-opener against West Coast.

"Games come around pretty quickly, the season comes around pretty quickly, so the focus will be on getting through training over the next six or seven weeks," O'Riordan added.

"And then we have the pre-season comp and the season will be upon us before we know it...hopefully we have a big one."