Figure 1 : Frost timing spatial patterns.

From: Observed variations in U.S. frost timing linked to atmospheric circulation patterns

Figure 1

(a) Time-average day of year with last spring frost. (b) Time-average day of year with first fall frost. (c) Objective clustering of stations into four regions based on day of year with last spring frost. (d) Objective clustering of stations into four regions based on day of year with first fall frost. In all panels, black dots indicate the locations of the 523 GHCN sites.