Paris flooding and train service interruption

Just off the top of my head, I think the St Michel RER B station is unaffected. It is the RER C station at St Michel-Notre Dame, which is along the banks of the Seine that is affected by the flooding. When I ask the RATP to get me from CDG to St Michel-Notre Dame tomorrow, it shows no disruption of service.
Edit - Here is the official announcement.

SEINE FLOOD: INTERRUPTED TRAFFIC ON LINE C OF THE RER BETWEEN JAVEL AND PARIS AUSTERLITZ, AVENUE HENRI MARTIN AND PARIS AUSTERLITZ AND BETWEEN VIROFLAY RIVE GAUCHE AND SAINT-QUENTIN EN YVELINES.
7 stations are closed at least until Friday, February 9th included: Saint-Michel Notre-Dame, Orsay Museum, Invalides, Alma Bridge, Champ de Mars, President Kennedy Avenue, Boulainvilliers.
Traffic is interrupted between Viroflay Rive Gauche and Saint-Quentin en Yvelines until Sunday 04 February included.

Note that the RER C platforms are totally separated from the RER B platforms. In fact, it is a bit of a walk between them.

Paris is not flooded. The RER B is not closed. The St. Michel station is not closed. The RER C is not running because its location makes it potentially vulnerable not because it is flooding. The Louvre has moved some art up as a precaution (we all remember what happened to Florence in 66 when a lot of their priceless Renaissance heritage was destroyed by flooding and valuables had not been moved to be saved) but there is also no flooding in the Louvre.

The main effect on tourists is that the Seine Cruises are not running because the boats can't get under the bridges and the concrete banks along the Seine in Paris are flooded; these are not the regular roads or sidewalks.

Sam and Janet are both correct. You should be fine on the RER B into St Michel.

Kim's most recent post on this thread indicates that the closure is extended through Feb 10. Click on the article she links to to see photo's of the issue. Water seeping up through the railroad bed is why they have shut down the trains along the river.
https://community.ricksteves.com/travel-forum/france/rer-c-stations-closed-within-paris-due-to-high-waters-of-the-seine

Hi Janie. I just took the RERB home from work last night from the south of Paris to St Michel and got off there. The train was still going further on to CDG. It's completely up and running. A portion of RERC is down that runs along the Seine, however, as it's exposed to the elements (not a tunnel) and runs near normal river level, so easily floodable. RERB runs through a tunnel under the Seine, so ok for now. Enjoy your stay in Paris and be sure to bring some thermal underwear. It's incredibly cold here and looks like possible snow when you arrive on the 9th which will make it even more beautiful! Dee Ann

The RER B has never been out of service during this current Seine flood event.

Thank you all for your responses. Coming from Florida the cool temps will be bracing so the tip about the thermals is appreciated. We have been following the weather and temps but hoped it would warm somewhat. We do love the city and will enjoy our trip.

I always travel with a set of silk long johns except in the middle of summer; when you are out and about and the weather is chilly they are a perfect extra layer and don't get hot and miserable in the overheated indoors. Right now thought the thermals sound also like a good idea. I live in Chicago and my silks were adequate to make my jeans wearable in the 4F weather this past week. The great thing about silks is that they take up no weight or space so you can throw them in without factoring in the space needs of extra stuff; once made Spain in late April in a cold snap more bearable with my tropical clothes on that trip.

Consider taking a taxi from CDG to your apartment. The set price to the left bank is 55 Eu and for two people that may seem reasonable.

It's extremely cold in Paris, temperatures are supposed to dip to - 4 C. Bundle up.
For that reason, I'd advise a taxi, which will take you door-to-door.

It has now been snowing for the last 2 nights and most of the weekend. Doesn't look like it will stop, either.
Sure is pretty, though - a veritable white-out.

Stay informed . . .a good site in English
https://www.thelocal.fr/

More specifically today
https://www.thelocal.fr/20180206/snow-and-ice-causes-travel-disruption-around-france

for weather
http://www.meteo-paris.com/ile-de-france/previsions.php