X-Plane 10.40 includes the capability to download as well as create your own weather and winds. Real-world weather is provided by hourly METAR reports that cover the entire world, while real world winds are available only in the United States with data provided by NOAA.
To use real-world weather, you can check the “use Real-Weather and Winds-Aloft” from the Quick Flight screen, or you can select it from the Weather screen, an option found under the Environment menu. There, select the large radio button at the top of the window labeled grab real weather from the net. Check the box labeled Download Real Weather files from the net. X-Plane will automatically download the weather METAR and winds aloft file, and will set a timer to re-download in one hour. If you want to download weather at some other time, you can always come back to this window and press the Download right now button.
If you would like to add in your own custom weather, add lines to the METAR.rwx file that list the reporting station name as MDEG. Then add the longitude, latitude, and elevation. Next, enter the METAR report you want to apply at that location.
For example, if we wanted to change the weather for the South Carolina area, we would specify the area in the METAR.rwx file as:
MDEG -81.235425 34.5647 80.0
After that we’d enter:
24031KT 2SM CLR 10/M10 A3011
for our weather.
If you would like to manually specify the wind at any location, open the winds.rwx file. Start a new line at the end of the file with “DEG,” then enter the latitude and longitude for the location. Each of numbers after the latitude represent the direction, speed and temperature. Each column of wind information corresponds to a specific altitude: 3000, 6000, 9000, 12000, 18000, 24000, 30000, 34000, and 39,000 feet. Note that you may leave a lower altitude column blank if the location is already above that altitude.
DEG -82.235 34.345 2910 3117+14 2925+08 2934+04 2924-07 2836-20 284436 284946
Let’s parse the first few items in our example above. Note that X-Plane uses longitude first, then latitude; thus the location is 82.235 degrees West, 34.345 degrees North. At 3000 feet, the wind direction is 290, with a speed of 10 knots. At 6000 feet, the wind direction is 310, speed 17 knots, and a temperature of +14 degrees Celsius. Continue on in this manner when you are adding custom winds or interpreting the report.