The National Weather Service issues Red Flag Warnings & Fire Weather Watches to alert fire departments of the onset, or possible onset, of critical weather and dry conditions that could lead to rapid or dramatic increases in wildfire activity. 
A Red Flag Warning is issued for weather events which may result in extreme fire behavior that will occur within 24 hours. A Fire Weather Watch is issued when weather conditions could exist in the next 12-72 hours. A Red Flag Warning is the highest alert. During these times extreme caution is urged by all residents, because a simple spark can cause a major wildfire. A Fire Weather Watch is one level below a warning, but fire danger is still high. 
The type of weather patterns that can cause a watch or warning include low relative humidity, strong winds, dry fuels, the possibility of dry lightning strikes, or any combination of the above.

During heightened fire danger, CAL FIRE will place additional firefighters on duty, staff more fire engines and keep more equipment on 24 hours a day to be able to respond to any new fires. CAL FIRE urges Californians to be extremely cautious, especially during periods of high fire danger. It's important all residents and vistors take steps to prevent wildfires. One less spark could mean one less wildfire.