Climate Matters is a localized climate change reporting resources program developed to support TV weathercasters across the United States. Developed as a pilot test in one media market in 2010, it launched nationwide in 2013; in the Fall of 2019 more than 797 weathercasters were participating in the program. In this paper we present evidence of the impact of the Climate Matters program on American’s science-based understanding of climate change. We analyzed three sets of data in a multi-level model: 20 nationally-representative surveys of American adults conducted bi-annually since 2010 (n=23,635); data on when and how frequently Climate Matters stories were aired in each US media market; and data describing the demographic, economic and climatic conditions in each media market. We hypothesized that: (1) Reporting about climate change by TV weathercasters will increase science-based public understanding of climate change; and (2) this effect will be stronger for people who pay more attention to local weather forecasts. Our results partially support the first hypothesis: controlling for market-level factors (population size, temperature, political ideology, and economic prosperity) and individual-level factors (age, education, income, gender, and political ideology), there is a significant positive association between the amount of Climate Matters reporting and some key indicators of science-based understanding (including that climate change is occurring, primarily human caused, and causes harm). However, there was not evidence for the second hypothesis. These findings suggest that climate reporting by TV weathercasters, as enabled by the Climate Matters program, may be increasing the climate literacy the American people.