The alternate freezing and thawing, along with intermittent wetting and drying of the soil on a bent grass putting green during the winter months is detrimental in many ways. These conditions produce a soil of a crumb structure, when this happens contraction and expansion take place. The resulting pressure separates the soil particles and fills the top layer of the surface with numerous pore spaces.
The paragraph above states an agronomic explanation which probably doesn't make a lot of sense to the golfer or someone who is not a golf course superintendent. So the question to be answered here is this. How does winter play affect the course conditions, so that ideal conditions may not be achieved when the spring season arrives?
The answer to this question in simple terms is this. The foot traffic of players over a small area such as a putting green develops surface compaction when the top layer is not frozen solid like the remainder of the soil is. A compacted surface layer of soil prevents the easy flow of food, water, and air into the lower soil regions where roots normally grow. When the growing season arrives in spring, the roots of the plants will not grow in soils where the natural channels and voids that have been destroyed by the compressing and crushing action of foot traffic on the thawed top layer of soil. Where there is no air there are no plant roots and thus there can be no turf.
The obvious reasons that most people understand are that ball marks on greens at this time make terrible scars and provide bumpy putting conditions as well as the indention from footprints. The underlying reasons of what was discussed above is that compaction and good golf turf just don't go together. However, let it be known that if the entire soil profile including the top layer is completely frozen no damage can occur, and in these conditions the course will be open for the brave souls who want to take on the cold temperatures while playing.
So when the course is temporarily closed during the winter it is done with the future in mind. If the course is not closed during the unfavorable conditions, the greens will be injured to the point where it will be impossible to provide good playing conditions for the remainder of the playing season. So why should the wishes of a few golfers wanting to play during the cold winter months interfere with the conditions for many golfers later on in the season? The answer to this question should be something to keep in mind.
"* USGA Journal and Turf Management source cited."