If you did not notice we had very cold days this winter and my company was working 7 days a week 14+ hours a day with freeze ups and no heat calls and resetting the temperature control on shower body's and water heaters and tempering valves
The hottest month of the year in New York City is
summer, with an average high of 84°F and low of 71°F. The cold season lasts for 3.3 months, from December 3 to March 12, with an average daily high temperature below 48°F.
NYC gets its water supply from Reservoirs that have temperature fluctuations during each season (Ambient temperatures affect the water temperature) Warm water enters a tank the water is hotter on the discharge, cold water enters a tank the outlet will be cooler depending on usage
I was in Brooklyn Supreme court 3 months ago testifying about a scalding cases where the temperature was 22 DEG high then it was set on the thermostat (I call it an aqua stat) on the water heater and how stacking also causes erratic temperature fluctuations
Here is a chart to explain temperature differences