James (Jim) Rodger Fleming was born on May 28, 1949, in Windber, Pennsylvania. He is the son of James and Ellen Fleming. After graduating from high school, Fleming attended The Pennsylvania State University, earning his Bachelor of Science degree in Astronomy in 1971. He then proceeded to earn a Master of Science degree in Atmospheric Science from Colorado State University in 1973. At that point in his life, he began his professional career as a meteorologist at the National Center for Atmospheric Research, followed by stints at the University of Washington and as a private consulting meteorologist until 1982. That year brought great changes to Fleming's life: he married Miyoko Yamato in July (the couple has two children) and he returned to graduate school at Princeton University, where he earned a Master of Arts degree in 1984 and a Ph.D. in History in 1988.

Following his doctoral degree, Fleming received an appointment as an assistant professor at Colby College. He was later appointed Director of the Science, Technology, and Society (STS) program at that institution.As he has begun to profess the discipline of STS, he has said that "my teaching is dedicated to bringing the sciences and humanities closer together. My research involves the history of science in America and the history of the geophysical sciences, especially meteorology." To that end, Fleming has not only spent his academic life at Colby College, but he has been a visiting professor and guest lecturer at universities throughout the country and the world.

Fleming's first major publication was the 1990 book Meteorology in America, 1800-1870. He describes the work as "a case study of complex change, cooperative institution building, and scientific controversies in early-national, Jacksonian, and Civil War America." In the book he details both the early stages of the science of meteorology, as well as the methods by which every-day people recorded the weather and climate. Reviewer Gale E. Christianson in the American Historical Review praised it as "an original contribution to the history of nineteenth-century science."

Fleming's second book was 1998's Historical Perspectives on Climate Change. That book, he writes, "addresses our concern over global warming, which has led to a rapid expansion in the literature on climate change...little work, however, has been done on the history of climate change itself." Isis reviewer Mark Monmonier praises the timeliness of the book's "comprehensive exploration of attempts to detect, explain, predict, and warn of salient trends in atmospheric temperature." Monmonier also lauds "Fleming's accessible prose and well-documented research" that makes for a "delightfully engaging volume." In addition to these two books, Fleming has edited a number of volumes of essays. He also edited the memoirs of Sverre Petterssen, the weather forecaster largely responsible for the choice of June 6, 1944, to be the date of the Allied invasion of Europe in World War II.

From 1990 to 1996, Fleming served as the history editor for EOS: Transactions of the American Geophysical Union, as well as guest editor for special issues. He has also completed a biographical work on the life of Guy Stewart Callendar, one of the leading figures in twentieth century climate studies, and his latest books include: Toxic Airs: Body, Place, Planet in Historical Perspective (2014) and Inventing Atmospheric Science: Bjerknes, Rossby, Wexler, and the Foundations of Modern Meteorology (2016). Fleming is currently a Charles A. Dana Professor and Director of Science, Technology, and Society (STS) at Colby College in Maine and was elected to chair the societal impacts of science and engineering section of the American Association for the Advancement of Science (AAAS) in 2014-2015.