The NRL have adjusted kick-off times for the second week of the pre-season challenge on Saturday ahead of forecast extreme heat across New South Wales.

Saturday's games were originally set to kick-off at 3:30pm (AEDT) in Mudgee for the Charity Shield between the St George Illawarra Dragons and South Sydney Rabbitohs, before heading to Penrith for the World Club Challenge at 6pm (AEDT) between the Penrith Panthers and St Helens.

The forecast for Mudgee and Penrith on Saturday is set to see the mercury rise to a forecast top of 37 and 38 degrees respectively, according to the Bureau of Meteorology.

The day was set to wind up on the Sunshine Coast - where the temperature is forecast to be a much cooler 29 degrees - as the Broncos clash with the Cowboys.

The NRL have made the call to move all three games back by 50 minutes though in an attempt to beat the heat.

The new schedule for Saturday is as follows:

4:20pm — Dragons v Rabbitohs at Glen Willow Oval, Mudgee
6:50pm — Panthers v St Helens at Bluebet Stadium, Penrith
8:55pm (7:55pm local) — Broncos v Cowboys at Sunshine Coast Stadium

RELATED: Pre-season challenge Week 2 team lists

The NRL thanked all clubs and broadcasters for their flexibility in a statement released to confirm the changes to the three matches on Saturday.

At one point, Sunday's games in Sydney - a double-header during the afternoon at Belmore - were also set to be played in conditions of up to 35 degrees, however, that forecast has now eased with the Bureau now forecasting a top of 29 degrees in Bankstown on Sunday.

The Wests Tigers will play the Canberra Raiders in the first game of that double-header at 2:55pm (AEDT), before the Canterbury Bulldogs clash with the Cronulla Sharks at 5pm (AEDT).

SEE MORE: Pre-season challenge ladder

The other two games on Sunday will see the Melbourne Storm head to Christchurch to play the New Zealand Warriors, and the Dolphins play the Gold Coast Titans in the final game of the weekend at Redcliffe.

The Friday night double-header in Gosford gets underway at 5:55pm (AEDT) as the Newcastle Knights play the Parramatta Eels, before the Sydney Roosters clash with the Manly Sea Eagles in the second game of the night.