Here Addie the new nurse walks into the show as a regular cast member, but in the next episode she and Zoe introduce themselves as if they're meeting for the first time.
When Addie walks in to the practice, Zoe introduces herself to Addie, and then Addie introduces herself to Zoe. Addie and Zoe worked together in the practice in the previous episode and clearly knew each other then as they called each other by name.
One of the plot points is a heat wave. In the preceding Gumbo & Glory (2011), which aired a week earlier, Zoe commented it was October 10 (coincidentally the air date). In the South, the hottest weather has subsided by then. The type of weather depicted takes place in July or August.
The basis of the story is that it is hot and everyone is suffering in the sweltering heat. However, even in southern Alabama, essentially everyone has air-conditioning.