You might have to experiment to find out, since, by the calendar, it's several weeks too late to sow grass seed in Maryland, even though real-world weather impacts might extend the season a bit. However, an important factor in plant growth, daylength, is of course not weather-dependent, and once the days get too short, grass will pause growth, so even seedlings that don't freeze because of a warm spell might not establish well, or with enough vigor. What percentage of them that successfully germinate and survive the winter will be hard to predict. Therefore, if the nights look frost-free for at least two weeks, you can try sowing seed, but be prepared to reseed again in spring to fill-in sparse areas. Or, just delay seeding until spring if erosion isn't a big risk; it's not the ideal season (that window was mid-Sept to mid-Oct), but it's the second-best timeframe. For bare areas needing patching, sod will establish faster than seed because it has a head start, but both will need regular monitoring for watering needs, as they can't dry out as they establish. If a hose were to freeze overnight and you needed to water seedlings or sod, that might make irrigation more of a hassle.

As far as what seed to look for, varieties of tall fescue that are listed in the recommended cultivars publication (see link), a report of locally-tested proven performers, is the ideal choice. That said, it can be hard to find a seed blend that uses more than one of those varieties; still, one is better than none. You're probably more likely to find them included in locally-bagged seed (say, companies based in the Chesapeake watershed) than nation-wide brands that don't customize seed variety blends to specific areas; the mid-Atlantic has challenging conditions that aren't shared by other turf-growing regions. Extension doesn't collect information on what retailers are stocking and what area brands are offering, and we don't make recommendations for particular businesses. So while we don't have a list of suppliers to share for you to check with, we would presume that locally-owned, independent garden centers or possibly farm supply stores would have more options overlapping with that recommended varieties list than a hardware store or nationwide turf brand would, but you may have to just see what's available. This late in the season, seed supplies in general might be pretty light, as the stores probably stocked-up with fresh seed around Labor Day.

Other useful information can be found in the pages grouped in our Lawn Care and Maintenance web resources, including about soil testing, fertilization (the legal cutoff date in Maryland is Nov. 15), liming (when needed), core aeration, and watering after seeding.

Miri