jump in snow, rain, mud, shows do not run only in the sunshine. How can a horse be expected to adjust to different enviromental conditions if he is only ridden in Sunshine or indoors on perfect footing??
One must practice saftey and common sense first and know the land.
Our OP may not have the experience needed for judging the climate or the solidity of the ground.
Jumping under a coach/instructor would be her safest option until she has gained some knowledge.
We also plow our one riding field.
Not with a field plow....but a snow plow for a tractor that has ridge setters to grade/fill in the tire tracks as well.
If one does not plow to the ground, leaving 6-8 inches of soft snow on top of a tiled sand ring.....you do not get ice unless a thaw of above 0 and a freeze again.
We use bioron/salt and sand to help with this.....I also rotate my riding pattern.
You know....we did not have arenas as a youngster like it is common tody.
Many of our Olympic riders trained outside...before there was a Florida winter curcuit.
It is only because we have become accustom to these luxeries that we forget horses can/ did and were "safely" trained and jumped outside.
It is a state of mentality....winter means stop riding outside for most people
...too bad....it is a lovely season to ride in
If horses can run, jump, buck, bolt, spin, play halters in the snow.....they can be balanced enough by the knowledgable rider to jump an obstacle
Sweden held Winter horse shows regularly.