We compiled observations of 116 nesting events by 37 female Blanding's turtles between 2013 and 2017 for a population located along the western shore of Lake Michigan, USA, to identify triggers of nesting activity. Across years, nesting dates were negatively related to average daily temperature during April and May, such that each degree increase in average temperature during April–May was associated with a 7-d-long shift earlier in nesting (defined as the date by which 90% of females had nested). Within years, nesting was more likely to occur when mean daily temperatures were > 18.9°C, the moon was in its brightest phase, and wind emanated from the east or south. These thresholds may be useful for timing interventions to protect nests and nesting female Blanding's turtles, although they may differ among populations across the species' range.