This article demonstrates how to change your design day weather conditions.
The weather data can be found under the Weather manager tab of Data Manager Ribbon.
The data for the site location you have selected for your building will be displayed by default. Here, you can specify the Cooling Design Day and Heating Design Day temperatures.
The design cooling day and Design heating day are the ideal conditions for assessing the energy efficiency of a building. There are certain conditions and standards prefixed for assessment, such as 0.4% cooling by ASHRAE or 1% cooling by ASHRAE etc:
The prefixed design day might not be the worst situation in your location, in that case you can change the design day temperatures according to your preference.
To do so, select User supplied data, and you will then be able to enter the required conditions directly:
Please note that custom weather data files can also be imported as shown in this wiki.