Table 3. — Rainfall intensity classes by number of days per month 



(Av. 1950-58) 



Weather Month 



station May June July 





Normal 



0.0- 



0.01 - 





Normal 



0.0- 



01 - 





Normal 



0.0- 



0.01 - 







ppt. 



trace 



0.25 



0.26 + 



ppt. 



trace 



25 



0.26 + 



ppt. 



trace 



0.25 



26 + 



Anchorage 



0.51 



26.6 



4.0 



0.3 



0.89 



21 .3 



7.9 



0.8 



1 .55 



1 8.9 



9.4 



2.7 



Bethel 



.89 



18.6 



9.6 



.8 



1 .20 



18.1 



10.8 



1.1 



2.29 



15.5 



13.0 



2.4 



Fairbanks 



.74 



25.2 



5.3 



.5 



1 .37 



20.7 



7.8 



1 .5 



1 .92 



16.3 



8.6 



2.1 



Fort Yukon 



.32 



28.0 



2.8 



.2 



.71 



23.8 



5.7 



.5 



.96 



25.3 



5.4 



.3 



Galena 



.63 



24.5 



6.1 



.4 



1 .69 



21 .4 



7.7 



.9 



2.69 



19.4 



9.4 



2.2 



McGrath 



.94 



23.8 



6.5 



.7 



2.06 



19.6 



9.1 



1 .3 



2.32 



17.8 



9.8 



3.4 



Northway 



.72 



23.0 



6.9 



1.1 



2.00 



19.5 



8.7 



1.8 



2.89 



18.4 



10.6 



2.0 



radiation and the surrounding air mass. Both 

 exposure and arrangement of fuel particles bear 

 on the actual temperature the fuel attains. Air 

 temperature also affects the rate of moisture loss 

 following a period of wetting by rain or dew. 



Temperatures are higher in the Interior Basin 

 than in any other zone. Nowhere do they stay 

 above 80° F. for extended periods (table 4), but 

 the sustained level over a period of 18 hours 

 decidedly affects fuel moisture and fuel tempera- 

 ture. 



Table 4. — Average daily air temperature classes {degrees F.J by number of days 



in each temperature class per month 

 [Av. 1950-58) 



Fort Yukon receives slightly less than 2 

 inches of rainfall during the May-July period; 

 77 days are rain free, and more than one-fourth 

 inch will fall on only 1 day during the 3 months. 



TEMPERATURE 



Observation and knowledge of air tempera- 

 ture are important in studying fire behavior. 

 Their main value lies in the relation between 

 temperature and its effects on equilibrium mois- 

 ture content and on ambient air stability condi- 

 tions. Fuel temperature is affected by solar 



Weather Month 



station 









June 













July 









30-39 



40-49 



50-59 



60-69 



70-79 



80-89 



30-39 



40-49 



50-59 



60-69 



70-79 



80-89 



Anchorage 



0.1 



5.2 



15.9 



7.5 



1 .2 



0.1 







1 .3 



14.9 



1 2.1 



2.6 



0.1 



Bethel 



.9 



9.8 



1 2.4 



5.8 



1.1 











4.7 



1 6.8 



7.6 



1 .8 



.1 



Fairbanks 



.2 



2.3 



8.9 



1 1 .3 



6.1 



1 .2 







1 .6 



9.0 



1 1 .6 



7.0 



1 .8 



Fort Yukon 



.3 



3.0 



8.6 



1 1 .4 



6.3 



.4 



.2 



1 .4 



7.1 



1 2.3 



8.4 



1 .6 



Galena 



.2 



3.2 



1 1 .4 



10.6 



4.1 



.5 







1 .4 



1 1 .9 



1 1 .3 



5.4 



1.0 



McGrath 



.5 



4.3 



1 1 .3 



9.9 



3.5 



.5 



.1 



2.8 



1 3.0 



9.8 



4.2 



1.1 



Northway 



.3 



5.2 



10.5 



10.2 



3.5 



.3 



.1 



3.2 



10.9 



10.8 



5.3 



.7 



Afternoon temperature affects the plans for 

 control of fires. As the long day progresses, 

 fuel moistures reach or approach equilibrium 

 moisture content. This in turn increases flamma- 



bility. More days have higher afternoon tem- 

 peratures at Fairbanks than at Anchorage (table 

 5). This fact may be directly related to the greater 

 fire problem in the Fairbanks area. 



27 



