Cold equipment

Your French press is sitting on a cold counter. You pour in hot water, and it immediately cools. The glass or steel absorbs heat. Solution: preheat your press with hot tap water before you start. Swirl it around, dump it, then add your coffee and water.

Coarse grind

You've been using the same grind setting all year. In summer, it works. In winter, it's too coarse. The water isn't hot enough to extract through big chunks. Solution: go one or two clicks finer on your grinder. Not espresso fine, just slightly finer than your usual coarse.

Rushed steep

You're in a hurry, or you're used to 4 minutes. But cold air slows extraction. Solution: extend your steep to 4.5 or even 5 minutes. Watch the clock, don't guess.