The name "Eismitte" means Ice-Center in German language, and the campsite was located  from the coast at an estimated altitude of 3,010 meters (9,875 feet).  The coldest temperature recorded during the expedition was −64.8 °C (−84.6 °F) on March 20, 1931, while the warmest temperature noted was −1.8 °C (28.8 °F) on July 9, 1931.  For the 12-month period beginning August 1, 1930 and ending August 5, 1931, the warmest month, July, had a mean monthly temperature of −12.2 °C (10 °F), while the coldest month, February, averaged −47.2 °C (−53 °F).  Over the same period a total of 110 millimeters (4.33 inches) of water-equivalent precipitation (meteorology) was recorded, with most of it, rather surprisingly, being received in winter.  At the latitude of the camp, the sun midnight sun between May 13 and July 30 each year, and polar night between November 23 and January 20.
Question: When was the last month of sun midnight sun?
Answer: 30 July