First, it’s fantastic that as a student you are excited about saving and even thinking about the differences between short and long-term savings. The distinction is huge because how you choose to build your savings will differ depending upon when you will spend the money. Shorter term money is best left in interest-bearing accounts–such as savings accounts, CDs, and money market accounts–to help offset inflation. Longer term funds (especially retirement funds) are the ones that you want to be taking more investment risk with while you’re in your 20s or 30s.
One small nuance in your question that I want to highlight: you say you have: (a) savings accounts, (b) investments in stocks, and (c) an IRA. An IRA is like a big backpack–really useful as you carry it through life, so you need to choose wisely what you put in it. If your stock investments are within your IRA “backpack,” you are right on track. I highlight this because there is another way for you to own stocks — and that’s in a taxable brokerage account. At your age, my advice is to keep it simple and use your IRA for your long-term retirement savings and investments, and use those other interest-bearing accounts for your shorter term needs.
Now let’s get to the heart of your question!
While you are in college, my number one wish for you is that you accumulate no credit card debt. So I’d rather see you err on the side of saving for the short term over contributing to your IRA so that your money is more accessible to you, in case you need it. Keep in mind also that you can only contribute earned income to your IRA, so however much income you generate through whatever job you work–whether it’s babysitting or bartending–is the maximum you can put toward your IRA.
The IRS will allow you to make IRA contributions for the prior year up until March 15th of the subsequent year. (So you have until March 15th, 2012 to make a contribution for the 2011 calendar year). Knowing this, you could put all your savings during the year into short term funds, and at the end of the year after you’ve determined how much you’ve earned (and thus are eligible to contribute to your IRA) you can take the leftover savings and turn that into an IRA contribution for the prior year. That way, you’ll ensure that you’re not tying up too much of your money in a way that could hurt more than help your efforts to save.
Once you are out in the regular work force, I’d recommend setting a monthly amount that you contribute to a 401k or IRA. Ideally in your 20s and 30s, I’d love to see you put 10% annually of your income into your IRA or 401k and set 10% aside for nearer term needs–which at that stage can include things like paying for graduate school, a down payment on a home, paying for a wedding, and so on. But while you are still in school, I think using the IRS clause that enables you to contribute in arrears may be just thing to help you manage that cash flow issue more effectively.