In most of the country it lands between mid-September and late October. Nine things worth doing before it does, and the last one saves a burst pipe.
Frost forms when air at ground level touches 32F. Northern gardens see it by mid-September; the far South can wait until December. Your date sets everything else.
Tomatoes, peppers, basil, squash and cucumbers are finished at 32F, with no recovery afterwards. Clear the plants the afternoon before the first cold night.
Kale, carrots, parsnips and Brussels sprouts turn stored starch into sugar in the cold. They genuinely taste better after a frost, so let them keep standing.
Tropicals such as hibiscus and bougainvillea suffer long before frost, and most want to be indoors once nights drop below 45F. Check the leaves for pests first.
A cold frame, or a sheet draped all the way to the ground, traps heat rising from the soil and buys a few degrees. Edges must touch down. Uncover it by morning.
Damp soil holds far more heat than dry soil and releases it slowly overnight. A deep watering ahead of a frost night is the cheapest protection in the garden.
Mulching too early keeps soil warm and invites rodents in. Wait until the top inch has chilled, then spread two to four inches to stop roots heaving in freeze cycles.
Set cloves two inches deep and six inches apart, two to four weeks before the ground freezes. They root through autumn, wait out winter, and are ready by July.
Water expands about 9% as it freezes, which is enough to split a tap or a hose left full. Drain the hose, coil it dry, and close the outdoor valve for the season.
All nine steps are really one job: let the garden shut down on your schedule rather than the weather's. What goes in now is what comes up first in spring.