Extreme heat, fires and wiring and signal problems have caused major train delays throughout Sydney this afternoon.
In an announcement on their website, CityRail said trains across their network, except for the Eastern Suburbs & Illawarra Line, are delayed up to 40 minutes due to overhead wiring and signal problems and the extreme heat.
A grass fire is the cause for delays between Campbelltown and Moss Vale on the Southern Highlands Line.
Train tickets can be used to catch Sydney Buses and Sydney Ferries services instead.