A few drops of lighter fluid and the new plug is a big help. Even here when it gets into the 30s or high 20s mine are harder to start. That's when I quit using my clip on glow driver and go to my power panel with the juice turned up. I have a few of the .91s and for some reason they are very cold blooded?? Sometimes when it goes into the 20s {high 20s} I roll the engine over with my starter and have someone put there finger over the muffler hole too, sort of a close and open thing until it starts. I leave the driver on the plug and run my engine up to about 4000rpm for about a half minute or so then it's good to go.