I am not a meteorologist, but I’ve got a pretty good background in mathematics. Having taught the calculus sequence for many years, I can tell you that most students do not find the concepts of calculus that difficult. However, the algebra required to manipulate expressions so that the calculus can be applied is where they get tripped up. My suggestion: really brush up on your algebra skills. Practice, practice, practice with your ability to factor complex polynomial, rational, and transcendental expressions. If you can do that well, you won’t have much difficulty with taking derivatives and integrals.
Best wishes with wherever you decide to pursue your degree in meteorology. Don’t be afraid to talk to your professors and seek their help outside of class. Most will actually appreciate that you are interested in learning and are willing to apply yourself.