As a beginning skier you will probably be falling down a lot.
This means that you are likely to end up covered in snow even if the weather is nice.
If you are wearing a soft shell, the snow melting from your body heat is more likely to penetrate the shell and make you cold and uncomfortable.
Depending on the local climate, you may also have to worry about sitting in icy puddles on the ski lifts.
I'd definitely recommend wearing a hard shell as your outer layer.
outdoors.stackexchange.com/users/4030/Charles E. Grant
tl;dr
I don't think you need spent big money on a new jacket just to go skiing if you have a serviceable soft shell.
You can wear anything you want.
I know when the ski season is coming to a close some people go skiing in little more than bathing suits on warmer days, and there are competitions where people try to cross/jump over pools of ice water.
I skied nearly every day in Jackson Hole, Wyoming one season and my go to jacket was a soft shell with a wind proof membrane.
I chose that jacket because I would use the lifts and then hike out in the side country (out of bounds areas to the side of the patrolled areas).
When I hike I tend to heat up significantly so my soft shell allowed me to dump the excess heat.
I only used a regular hard shell ski jacket during the coldest of days.
In general for beginning skiers/snowboarders I'd recommend they wear something that is warm, has really good water resistance, and will keep the snow out.
Hard-shell skiing jackets generally accomplish all of these things.
Soft-shell jackets that I've used tend to be a bit shorter in the torso
so it is easier for snow to get up underneath your jacket.
Depending on how you fall and what type of snow you fall into the snow will be driven underneath your jacket.
This is why some ski jackets have a "powder skirt" built into them.
If you're wearing pants this is a bigger deal than if you're wearing overalls aka bibs because the snow has a better chance with pants to directly contact your skin.
Keep in mind you're probably going to be falling a lot as a first timer so bigger, bulkier clothing is going to keep you warmer and cushion your falls a tad too.
The long and the short of it is I'd recommend a big hard-shell jacket, and bibs.
If you're learning to snowboard and happen to have a set of hockey breezers I'd recommend you wear those too.
However, anything you have, like a soft shell, that will keep you warm and dry is probably okay even if it isn't optimal.
This is especially true if you are going skiing at a ski area since the lodge is close and will allow you to warm up.
As an aside don't discount the psychological benefits of a warm drink.
I almost always bring a small thermos full of hot tea with me while skiing.
The tea is always nice, but it is a real lifesaver when you're wet, tired, and feeling miserable.
outdoors.stackexchange.com/users/7995/Erik
If I go skiing during sunny weather conditions, is it still recommended to use hard shells or could I get away with an insulated/soft shell jacket and pants?
Yes you get away without hardshells in those conditions.
Your main enemy will be relative wind speed (also because of your speed while skiing) and the cold.
It can be could in sunny (dry) conditions of course.
So you need good insulation which you should be careful of.
The main reason for hardshells are wet conditions.
Softshells ( regarding a typical definition ) are resistant to some degree of humidity like decent rain over limited time or e.g. sitting in snow for limited time.
Still for intense rain/snowfall you won't stay dry in softshells.
So I recommend that you have at least a windproof softshell (e.g. Windstopper) and decent insulation.
All above is valid for upper and lower body.
outdoors.stackexchange.com/users/2653/Wills
The question is really what you mean by sunny weather conditions ?
Does it means the weather is hot or does it means the sun is shinning ?
Because in winter, you can have a beautiful sunny sky and extremely low temperatures altogether.
For instance in winter you can have 40°F in the resort and 0°F at high altitude.
In my opinion the relevant question is wether it will be hot or cold !
If the weather is cold then you definitely need warm clothes, and as other members have already said, hardshell is really useful against the cold wind.
Don't forget that a significant part of your time will be spent doing nothing on the skilift, exposed to wind and cold seats.
If the weather is hot then this is becoming problematic, because you'll be very hot doing a sport with a hardshell in these conditions.
I have ever skied in April under hot conditions, and clearly shorts and T-shirt were sufficient.
But there are 2 issues when it is hot: snow is wet, if not small ponds everywhere falling onto bare skin hurts a lot
So as a beginner, I assume you'll fall quite a few times, and get very wet
, so water-resistant clothes are definitely a plus (if you wear jeans for instance, they will be wet quickly and will keep this way all day long).
Also to avoid being burnt or tear your clothes apart when falling it is better to have clothes made with solid tissue.
The ideal would be to have some hardshell clothes without warm padding.
outdoors.stackexchange.com/users/11911/pilko
Since you get a lot of wind skiing you need to break the wind.
And you don't need as much breath-ability.
But in sunny conditions you can get away with a bit.
You are not going to have a lot of speed
your first time skiing.
I just saw you live in Houston.
If you just have a soft shell for local weather then get a hard shell.
At like Academy or an army surplus you can decent shell / rain jacket for $80.
A pair heavy wool pants will work fine.
outdoors.stackexchange.com/users/6728/paparazzo
I'm going skiing for the first time. From what I've read, most everyone uses hard shell jackets and pants for skiing. However, they usually mention something about skiing in bad weather, frigid cold temperatures, long hours in the back country, etc.  If I go skiing during sunny weather conditions, is it still recommended to use hard shells or could I get away with an insulated/soft shell jacket and pants?
Do I need a hard shell to ski in sunny weather conditions?
outdoors.stackexchange.com
<clothing><winter><skiing><sun>
outdoors.stackexchange.com/questions/14615
outdoors.stackexchange.com/users/3066/Chris Mendez
 The ideal would be to have some hardshell clothes. However, you don't need spent big money on a new jacket just to go skiing if you have a serviceable soft shell and decent insulation.   You can wear whatever you want, though hardshell is best followed by windproof softshell.
Hardshell is best, though windproof softshell can also work. You can wear whatever you want.