A Met Office yellow alert covering London began at 10am and runs through to 9pm, covering a large swathe of central, southern and eastern England, including London.
A number of train services, including some on London commuters lines, have been cancelled due to falling trees.
Here is a list trains that have already been cancelled or impacted on Friday:
Southern, Thameslink & Gatwick Express
Early on Friday, Southern Rail announced a lightning strike at Normans Bay prevented trains from stopping at the station.
Elsewhere, several fallen trees have affected services, including a number of commuter services to London.
A tree falling on the platform at Angmering earlier this morning is affecting services between Worthing and Angmering.
A tree blocking the railway at Moulsecoomb has affected services between Lewes and Brighton, and another at Uckfield earlier this morning has impacted services between Crowborough and Uckfield.
Many services are cancelled or delayed due to Storm Austen
Southern Railway
Services between Haywards Heath and Brighton have been affected by a tree on the line at Balcombe, and another at Swanwick earlier this morning has led to a reduced service between Southampton Central and Fareham.
CrossCountry
CrossCountry have made some amendments to their service until the end of Saturday due to Storm Austen.
There will be no CrossCountry services operating between Plymouth and Penzance on Friday, with further changes to services between Bristol, Plymouth and Penzance on both Friday and Saturday depending on the storm’s impact.
Great Western Railway will be accepting CrossCountry tickets between Cheltenham Spa and Penzance at no extra cost.
Great Western
Speed restrictions imposed on routes in Devon and Cornwall means that fewer Great Western Railway will be operating today.
Long distance services towards Devon and Cornwall will run between Reading and Plymouth only, with connections onto local services.
A number of early-morning services were also cancelled to allow teams to assess the impact of any damage in full daylight.
Rail replacement coaches are running between Exeter St Davids, Okehampton Interchange and Okehampton, in both directions.
Storm Austen has brought strong winds and heavy rain across much of southern England
AFP/Getty
Trains between Par and Newquay are suspended due to a tree on the line, with rail replacement taxis being requested.
Another tree on the line means that trains between Truro and Falmouth Docks are running at a reduced speed.
The route is running a reduced service, with trains from Truro leaving at 15 minutes past the hour, and trains from Falmouth Docks at 45 minutes past the hour.
Northern
All Hull to Halifax services will start and end at Bradford Interchange, while some Leeds to York via Harrogate services will be revised and will either not call at Weeton or Headingley, in both directions.
Some Leeds to Chester services will not call at Bramley, in this direction only, and some York to Blackpool North services will not call at New Pudsey.
Ashington to Newcastle services will not call at Northumberland Park, while some Blackburn to Headbolt Lane services will not call at Smithy Bridge.
South Western
A number of trees blocking the railway is causing havoc to many South Western services.
A tree blocking the railway between Branksome and Bournemouth means all lines are blocked, with trains running between Weymouth and Bournemouth delayed by up to 45 minutes.
Storm Austen weather warnings
PA Wire
Response teams are now on site to remove the tree from the line, but services between Weymouth, Poole, Bournemouth and London Waterloo will be subject to delay, alteration and cancellation today.
Trains for Brockenhurst - Lymington Pier services have also been suspended until further notice due to the incident.
Another tree blocking the railway at Horsley has disrupted service between Guildford and Effingham Junction.
The tree has now been removed but there are still cancellations and delays as service recovers.
A tree blocking the line between Swanwick and Fareham has also been removed, with continued delays affecting Southampton Central to Portsmouth & Southsea stopping services.