A rail strike is reported starting evening of 25 January. Since the train won't be operating, how can I get to FCO for a noon flight? Thanks
You can take a taxi.
Strikes do not always happen on the projected date, so keep tabs on the situation.
Sometimes there is a settlement or the two sides agree to keep talking and the strike
action is deferred.
Secondly, trains are at some level required to run by law during rush hours, so
apart from the taxi, or also the bus, trains may run some of the time.
The standard airport website is a good place to start for researching stuff like this.
There are also buses. Here's some information, but it is not an official website: https://www.roma-airport.com/bus.php#google_vignette. And another website: https://fiumicinoairport.com/fiumicino-airport-transfers/bus/#/search.
Since the train won't be operating
Says who? Well, whoever is, he is wrong: https://www.trenitalia.com/content/dam/trenitalia/regionale/treni-garantiti-festivi/LAZIO-treni-garantiti-festivi.pdf