There's no reason that your garage floor should look anything less than showroom condition!
#FastTipTuesday - Winter Warm-up!
When you paint in the winter, the surface you are painting may be colder than the ambient temperature. So be sure to give the areas like exterior concrete time to warm up to 3C above dew point before you paint and avoid painting during a cold snap.
Check your tin for drying times between coats - it will e longer in colder weather. Plan your painting for the middle of the day and finish early enough to allow the last coat time to dry before it gets too cold.