Climate data from NOAA/NWS Co-op Network stations are complied in Table 4.2-1 and the locations are shown on Figure 4.2-3.  Figure 4.2-3 also shows precipitation data from the Spatial Climate Analysis Service (SCAS) at Oregon State University.  The Bill Williams Basin does not contain Evaporation Pan, AZMET and SNOTEL/Snowcourse stations.  More detailed information on climate in the planning area is found in Section 4.0.3.  A description of the climate data sources and methods is found in Volume 1, Appendix A.  For a link to the web site for each climate data source click its header.

NOAA/NWS Coop Network

• Refer to Table 4.2-1A   

• There are four NOAA/NWS Co-op network climate stations in the basin. The average monthly maximum temperature occurs in July and ranges between 78.3°F at Hillside 4 NNE and 92.5°F at Alamo Dam.  The average monthly minimum temperature occurs in January or December and ranges between 41.3°F at Bagdad 8 NE and 50.6°F at Alamo Dam.

• Highest average seasonal rainfall occurs in the winter (January - March), summer (July – September) or fall (October-December).   For the period of record used, the highest annual rainfall is 15.84 inches per year at the Hillside 4 NNE station and the lowest is 8.59 inches per year at Alamo Dam.

SCAS Precipitation Data

• See Figure 4.2-3

• Additional precipitation data shows rainfall as high as 24 inches northeast of Skull Valley approaching Granite Mountain, elevation 7,626 and as low as four inches in the western portion of the basin along the Bill Williams River.

• This basin contains the largest range of average annual rainfall in the planning area with 20 inches separating areas of highest and lowest precipitation.

Click for Figure 4.2-3 Bill Williams Basin Meteorological Stations and Annual Precipitation

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