Hourly Forecast Detailed. 1  0am:The Bossier City, LA forecast for Apr 20 is 73 degrees and Clear. There is 72 percentage chance of rain and 7 mph winds from the South. 2  3am:The Bossier City, LA forecast for Apr 20 is 70 degrees and Mist. There is 83 percentage chance of rain and 5 mph winds from the South. 6am:The Bossier City, LA forecast for Apr 20 is 67 degrees and Fog. There is 90 percentage chance of rain and 5 mph winds from the South.