About Weather Data from the Fire Environment Mapping Service (FEMS)

Fire Environment Mapping Service (FEMS) is the official system for applying the National Fire Danger Rating System (NFDRS), providing access to fire environment datasets and online analysis tools in support of wildland fire preparedness and operational decision-making.

FEMS datasets include:

• The full history of archived observations from the legacy live fuel moisture database.

• Fire Danger outputs for the Period of Record for RAWS, through October 31, 2025.

• Historical and current observations, and forecasts for weather and fire danger rating.

• Data from a limited number of ASOS and Mesonet stations.

Fuel Moisture Estimates

For those familiar with fuel moisture estimates calculated using the old Fosberg and Deeming (1971) method, it should be noted that FEMS uses the newer Nelson (2000) method. The Nelson method tends to predict higher 1-hour fuel moistures compared to the Fosberg method. See the table below for a quick summary of the differences.

Comparison of Fosberg and Deeming (1971) with Nelson (2000) fuel moisture estimation methods.

Estimation Details	Fosberg and Deeming (1971)	Nelson (2000)
Calculated using:	One daily set of weather values	Hourly weather values
Overall predictions tend to be:	static	dynamic, better capturing changes driven by precipitation, humidity, and & sunlight
1-hour fuel predictions tend to:	underestimate compared to drying and weighing fuel.	overestimate compared to drying and weighing fuel.
1000-hour fuel predictions tend to:	overestimate compared to drying and weighing fuel.

Additional Information

• Fire Environment Mapping System (FEMS) .

• FEMS Help Page

• FEMS RAWS Data List

• FEMS 'Whats New' Page