A quick pilot analysis was done for this proposal to estimate the magnitude of change in frost free dates. NOAA Daily Climate Normal data set from 1951-2010 was used to analyze the frost-free dates at 5,134 stations where frost occurred every year. This data differs from the more accurate data set used for calculating the NOAA climate normals. That data set applied homogeneity correction to account for systemic changes (urbanization, station moves etc.).The frost free date climate normals are not simple means but are calculated by a bootstrapping approach that samples across years and before and after the observed frost free date. This is a state-of-the-art method but it is designed to calculate the mean and variance of the frost free dates assuming the data are not trended. Key findings from the preliminary data are: ## Preliminary findings 1. **There is a strong regional difference in the timing of frost free dates, with the east showing earlier spring dates and later fall dates (see maps below).** 2. The average station is predicted to have frost free dates 3 days earlier in the spring and and 6 days later the fall of 2020 than it did on average over the period 1981-2020 with local station changes as large as 2-3 weeks. 3. Increased variability in frost free dates has been was hypothesized, but that was not a common occurrence in most regions. 4. Aggregated national trends mask these changes because a shortened western growing season offsets a lengthened eastern growing season.