Not online , but you can get warning board info by calling :-
0845 988 1188 and when prompted, press 1 immediately followed by the quickdial number :-
011131
Although , checking it now , it was last updated on Tuesday 25th and it is saying that the only red boards out are at Marlow. Not sure what the lag on this service is ...
If you are interested in the reach from Teddington to Molesey , we have a 'River Status' page on our website www.teddington-lock.co.uk
We try to update it in real time , certainly within 12 hours of a board change.