Hastings graduated magna cum laude with a Bachelor of Science in marine science and chemistry from the University of Miami, Coral Gables in 1998. After her undergraduate she did a research internship at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory in Princeton, NJ. She credits this position to her interest in atmospheric chemistry. By 2004 Hastings had completed her Ph.D. in the Princeton University department of Geosciences. Her thesis studied reactive nitrogen using measurements of stable isotopes and was titled "Studies of Reactive Nitrogen in the Atmosphere Using Global Modeling and Stable Isotope Measurements".