The City Definitions command is used to create and define environmental conditions for cities that can be used in projects. A default list of US cities, grouped by state, is included. The temperature numbers are the 1% numbers taken from ASHRAE Weather Data Viewer 2.1.
To view and modify the city list, go to
Ribbon: DMH: Customization->Master & Standards Customization-> 
City Definitions
Pulldown Menu: DM HVAC->Building Definition->Schedules->City Definitions
City List Dialog Box
See the Common Schedule Dialog Box Features section for more information about how this dialog box works. This section describes the Rename, Find, Previous, Next, New, Copy, Save, and Delete buttons.
Current City Group: The active city group is listed here. All of the glass types that are created and modified will be associated with this group. The default customization defines each state as a separate group.
Select City Group: Press this button to open the City Groups dialog box. The group selected will become the current group. See the Common Groups Dialog Box Features section for more information.
City: The name of the city.
Latitude: The latitude at which the city is located.
Elevation: The elevation at which the city is located.
Outside Air Temperatures
All temperatures are in degrees Fahrenheit.
OSA Low Temperature Dry Bulb: The temperature used when calculating heating loads.
OSA Daily Range: The temperature range during the day used when calculating cooling loads.
January, February, March, April, May, June, July, August, September, October, November, December: The outside air high temperatures used when calculating cooling loads for each month.
OSA High Dry: The outside air dry-bulb temperature for the specified month used when calculating cooling loads.
OSA High Wet: The outside air wet-bulb temperature for the specified month used when calculating cooling loads.