Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (1.1 MB)

Title: Differences in fire danger with altitude, aspect, and time of day

Author: Hayes, G. L.;

Date: 1942

Source: Journal of Forestry. 40(4): 318-323.

Publication Series: Scientific Journal (JRNL)

Description: The measurement of fire danger has progressed remarkably since the early days of measuring humidity alone, or humidity and wind, or humidity, wind, and rain at a few valley bottom stations scattered widely apart over a forest of a million acres or more. Measuring the moisture content of the fuels directly is now known to be more accurate than measuring humidity and rain and then estimating the fuel moisture and inflammability. Other factors, such as the shade of timber canopies of different densities, north-versus south-facing slopes, valley bottom versus ridge top or mountain top exposure, the greenness of vegetation, etc., are also now being recognized as significant. Obviously, all significant factors deserve careful consideration if danger ratings of any kind are to be used most effectively by field men. The hope or dream of one single, simple factor to be measured only once or twice each day at one station as a criterion of fire danger over a large area has now been completely abandoned in most forest regions. Forest fire danger is "not that simple." Furthermore, the protection of our forest resources from fire is now recognized to be of great enough importance to warrant much more than one measurement per day at one or two stations per million acres to determine what measures must be applied to safeguard them from destruction.

Keywords: fire danger, measurement, fuel moisture, inflammability

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.



Hayes, G. L. 1942. Differences in fire danger with altitude, aspect, and time of day. Journal of Forestry. 40(4): 318-323.


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.