If you are not planning on planting in that area until spring, you could put down layers of newspaper or cardboard, then mulch on top of it. If anything germinates, it will probably not be able to get through the paper (nut sedge aside) and will die under there. After a fall and winter of rotting, the paper will be mostly gone in the spring and you can garden away.

Laying newspaper or cardboard on soil keeps any plant under that mulch material from getting the sunlight plants need to grow and when you deprive a plant of the sunlight it needs that plant dies. Covering the paper mulch with another mulch material both hides the paper and helps hold it in place.
I have not seen either Yellow Nutsedge or Quackgrass grow through newspaper until the paper is fairly well digested by the soil bacteria, as long as the thickness is adequate.

It depends on the weeds and what you are going to do with the area. Some of annual seeds may germinate this fall, but will probably then winterkill if you do nothing. If the weeds were mustards, then many of them are likely to germinate and start growing this fall, go dormant for the winter, then go to seed next year, so heavy mulch or trifluralin would be beneficial to apply now to prevent them from growing.

Before you put down trifluralin, what will you use the site for next year? It could carryover into next year for weed control and if you plant susceptible seeds there, they won't grow.

Also, unless the weeds are fall annuals, most of the seeds will not germinate until next spring and that is when your bigger weed control problem will be.

There is really very little known about the long term affects trifluralin has one humans just as there is very little known about most synthetic poisons. it is knonw that failry low levels of th9is stuff is toxic to rabbits.

Here is a link that might be useful: trifluralin