The advice has come from South Western Railway (SWR) ahead of three days of industrial action.
SWR warned it would be run a ‘severely reduced timetable’ on Tuesday, Thursday and Saturday when the strikes are due to take place.
Trains will run between 7.15am and 6.30pm on some routes for those who have no choice but to travel.
It will see just two fast trains per hour in each direction between Waterloo and Southampton. The trains won’t stop at every railway station.
Other services between Waterloo and Windsor, via Hounslow, Waterloo and Basingstoke and Waterloo and Woking will also run a limited service.
All other services will be suspended, with SWR running a late-starting Sunday-level of service across the network on Wednesday, Friday and Sunday.
Claire Mann, SWR’s managing director, said: ‘The sheer scale of this planned industrial action severely limits the number of trains we can run and routes we can serve, which is reflected in the reduced timetable we have published today.
‘With this disruption set to be so considerable, I regretfully urge customers to only travel by rail if absolutely necessary between Tuesday and Sunday.
‘I am sorry these strikes will cause such disruption and am grateful to our customers for their patience and understanding as the rail industry works to bring this damaging nationwide action to an end.’
Island Line services, on the Isle of Wight, will not be affected by the industrial action.