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PMS 437

Fuel Moisture Sampling

  1. Online Fuel Moisture Sampling History
  2. Fuel Moisture Sampling Procedures

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

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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 or 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 uncompacted 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:
Fuel moisture sampling and estimation. This table provides means for tracking sample weights and calculating gravimetric fuel moisture.

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Questions? 
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NWCG is excited to announce that Quarter Three materials for the 2025/2026 Wildland Fire Leadership Campaign are now available. This annual initiative offers all students of leadership and wildland fire management an opportunity to engage with essential leadership skills and knowledge needed to lead effectively in dynamic environments.

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2025/2026 NWCG Leadership Campaign - Leadership Levels

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Date:  March 23, 2026
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The 2026 Core Components Module Package for RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR) and the 2025 Fire Year in Review are now available on the NWCG website. The 2026 Core Components Module Package provides all content needed to deliver RT-130.

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2026 Core Components Module Package

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NWCG is pleased to announce that the new S-490, Advanced Fire Behavior Calculations (Blended), 2026 course is now available.

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Paul Gleason Lead By Example Award

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