Extension, with its access to long-term volunteers, has the unique ability to teach citizen scientists about the connection between climate variability and the resulting effects on plants, animals, and thus, humans. The USA National Phenology Network's Nature's Notebook on-line program provides a science learning tool for Extension's Master Gardener, Master Naturalist, and Master Water Steward training programs, engaging volunteers to contribute to a scientifically rigorous data resource. We give examples of how Extension programs in Arizona, Florida, and Maine are currently incorporating Nature's Notebook, and encourage use of the program in other Extension locations.