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Fuel Moisture Sampling

Online Fuel Moisture Sampling History

Fuel moisture sampling can provide useful insight to current conditions if it is done consistently throughout each fire season.  Results from sampling efforts around the United States are stored in the National Fuel Moisture Database:

http://wfas.net/index.php/national-fuel-moisture-database-moisture-drought-103

Results for sampling history of both live and dead fuels are available for locations around the United States. 

Fuel Moisture Sampling Procedures

General Guidelines

  • Record site name, date, time, observer name, observed weather, general site description
  • DO NOT collect samples if water drops or dew are present on samples
  • Keep samples in a cool and dry location
  • Seal containers with tape that will not leave residue

Live Fuel Samples

  • Only collect foliage (needles) and very small twigs remove flowers, seeds, nuts, or berries
  • Pack containers loosely to avoid spillage but ensure container is full
  • Include stems of herbaceous plants
  • Replace lid on container immediately after collecting sample

Dead Fuel Samples

  • Samples should not be attached to live trees or shrubs
  • Avoid decayed samples that crumble or splinter when rubbed
  • Collect samples from several different plants
  • Ensure container is full or about 20 grams
  • Do not collect buried samples
  • Pick samples of different size within the time lag class
  • Recently fallen material should be avoided
  • Remove all lichen, moss, and very loose bark from sample

Duff and Soil Samples

  • Remove all soil and live tree or plant roots from sample
  • Avoid any soil particles in duff samples and vice versa

Litter Samples

  • Collect only un-compacted dry litter from both sunny and shady areas

Handling and Measuring Samples

  • Preheat drying oven between 60°C (140°F) – 100°C (212°F). Be sure to note temp used.
  • Place sample cans with closed lids on scale and record “wet” weights
  • Remove lid just prior to placing in oven. If material is lost, re-weigh sample
  • Dry sample for 24 hours (very wet samples 48 hours)
  • Replace Lids immediately after sample is removed from oven and weigh
  • Calculate fuel moisture using worksheet provided here: