Fuel Moisture

The Rancho Santa Fe Fire Protection District samples vegetation and produces a live fuel moisture report for the district. Fuel moisture content describes the moisture content within the vegetation/fuel. Moisture content is the single most important factor that determines how much of the total fuel is available for burning, and ultimately, how much is consumed. Fuel moisture determines if certain fuels will burn, how quickly and completely they will burn, and what phases of combustion the fuels will support. Fuels with a higher moisture content will not ignite or burn as quickly as they would if they had a lower moisture content.

Below you will find a chart indicating current live fuel moisture levels for coastal chaparral fuel types found within our district, Chamise and Ceanothus. Samples are taken at two locations within the district, the 7600 block of Artesian Road (site 1) and at the Olivenhain reclaimed water tank at the end of Alva Road (site #2). For comparison, a chart indicating the fuel moisture levels for the same fuel types sampled at Rainbow Camp is also shown. During the fire season, samples are taken every two weeks within the district and weekly at Rainbow Camp. When we are out of fire season, sampling is done monthly. The red 60% line on the chart indicates the level below which the fuel moisture is considered critical and will promote rapid fire growth.