Once you've got the basics dialed, there are a few extras that make cold-weather espresso less of a guessing game.

• A portafilter heater. Some machines have them built in, but if yours doesn't, you can put the portafilter on top of the group head to warm it while the machine heats. Or just run a shot of hot water through it.
• A small towel that's dry and clean. Keep it on your work surface to rest tools on—cold counters steal heat fast.
• A cup warmer or just warm your cup with hot water before pulling the shot. A cold cup can drop the espresso's temperature by 10 degrees before you even taste it, and that changes the flavor.
• A thermos or insulated mug if you're drinking outside. Winter shots die fast in cold air.