State Precipitation & Temperature Update for Arizona

Conditions through June 2006

Precipitation is monitored for the state of Arizona across the 15 major watersheds (see map left). From the stations within each watershed, mean values of precipitation for the watershed as a whole are computed. These mean values are ranked against the monthly mean values for the period of 1971-present. The rankings are then divided by the number of years of data and multiplied by 100% to create percentiles.

Here, precipitation percentile values for the most recent month, along with previous 3-, 6-, 12-, 24-, 36-, and 48-month total are shown for each watershed. Low percentile values (brown shading) indicate dry conditions while high values (green shading) indicate wet conditions. For example, a precipitation total that falls at the 100^th percentile means that it is the highest precipitation total for the 1971-present period.

Temperature is monitored for the state of Arizona across 7 climate divisions (see map left). From the stations within each climate division, mean values of temperature for the climate division as a whole are computed. These mean values are ranked against the monthly mean values for the period of 1895-present. The rankings are then divided by the number of years of data and multiplied by 100% to create percentiles.

Here, temperature percentile values for the most recent month, along with previous 3-, 6-, 12-, 24-, 36-, and 48-month averages are shown for each climate division. Low percentile values (blue shading) indicate cool conditions while high values (orange/red shading) indicate hot conditions. For example, a temperature that falls at the 100^th percentile means that it is the highest average temperature for the 1895-present period.

The maps of the 7 periods for precipitation and temperature are shown below, with tables of the percentile values and descriptive text following the maps. Values of -99 and grey shading indicate missing data. When the data are available, this product will be updated. Current update is 08/01/2006.

Precipitation Percentiles by Watershed (through June 2006)

Temperature Percentiles by Climate Division (through June 2006)

SHORT TERM CONDITIONS: 1-6 MONTHS

The month of June was characterized by above average precipitation across the entire state, although this should not imply a “wet” month, as normal precipitation for June is low. All watersheds except the Salt and Upper Gila were well above normal precipitation for the month. The Salt and Upper Gila were nearly normal. The month of June, 2006 was above the 98^th percentile for divisions 4, 5, and 6 across central Arizona, indicating that this past June was among the hottest Junes in the past 112 years. The Virgin River in the Northwest, the Lower Gila in the Southwest an the White Water Draw in the Southeast had nearly normal precipitation for the 3month period from April through June, while the Lower Colorado to the west and the San Simon River in the southwest had above normal precipitation for the past 3 months. All the other watersheds had well below normal precipitation from April through June. Temperatures were above the 95^th percentile in the Northeast, southeast and south-central portions of the state during the previous 3 months, and the rest of the state also had unusually high temperatures. The extremely dry winter is seen clearly in the precipitation percentiles for the past 6-month period, with all below the 20^th percentile except the Virgin River in the Arizona Strip. Temperatures for the winter were well above normal everywhere, with the northeast climate division on the Colorado Plateau being the highest above normal.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	78.57	CD1	92.86%
Upper Colorado	75.00	CD2	96.43%
Little Colorado	69.44	CD3	95.54%
Verde	72.22	CD4	98.21%
Bill Williams	86.11	CD5	99.11%
Agua Fria	75.00	CD6	98.21%
Lower Gila	94.44	CD7	93.75%
Salt	47.22
Lower Colorado	94.44
Upper Gila	47.22
Santa Cruz	-99
San Pedro	89.89
Willcox Playa	-99
San Simon	94.44
White Water Draw	63.89

JUNE 2006: percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	45.71	CD1	87.50%
Upper Colorado	30.56	CD2	98.21%
Little Colorado	30.56	CD3	93.75%
Verde	27.78	CD4	93.75%
Bill Williams	38.89	CD5	93.75%
Agua Fria	19.44	CD6	97.32%
Lower Gila	44.44	CD7	95.54%
Salt	27.78
Lower Colorado	72.22
Upper Gila	16.67
Santa Cruz	-99
San Pedro	33.33
Willcox Playa	-99
San Simon	66.67
White Water Draw	44.44

APRIL 2006 - JUNE 2006 (3-month): percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	55.88	CD1	78.57%
Upper Colorado	19.44	CD2	95.54%
Little Colorado	14.29	CD3	89.29%
Verde	16.67	CD4	93.75%
Bill Williams	11.11	CD5	84.82%
Agua Fria	13.89	CD6	94.64%
Lower Gila	16.67	CD7	94.64%
Salt	19.44
Lower Colorado	16.67
Upper Gila	13.89
Santa Cruz	-99
San Pedro	11.11
Willcox Playa	-99
San Simon	16.67
White Water Draw	11.43

JANUARY 2005 – JUNE 2006 (6-month): percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

INTERMEDIATE TERM CONDITIONS: 12-24 MONTHS

The intermediate time periods of 1- and 2-years show the importance of the historical context of drought. The 1-year period precipitation has been below the 15^th percentile for all watersheds except the 3 along our western border. The corresponding temperatures for the 1-year period have been among the highest ever, particularly in the southeast and south central climate divisions.

In stark contrast, the 2-year period shows very little evidence of drought across the western and central portions of the state, with precipitation totals well above normal. The Little Colorado and the southeastern watersheds show precipitation totals below the 30% percentile, with the driest watershed being the San Pedro. This 2-year period includes the extremely wet winter of 2005. Except for climate division 1 in the northwest, temperatures for the 2-year period were all at or above the 80^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	48.48	CD1	78.38%
Upper Colorado	11.43	CD2	91.89%
Little Colorado	11.43	CD3	91.89%
Verde	11.43	CD4	94.59%
Bill Williams	14.29	CD5	86.49%
Agua Fria	8.57	CD6	95.50%
Lower Gila	20.00	CD7	98.20%
Salt	8.57
Lower Colorado	31.43
Upper Gila	8.57
Santa Cruz	-99
San Pedro	5.71
Willcox Playa	-99
San Simon	5.71
White Water Draw	14.71

JULY 2005 – JUNE 2006 (12-month): percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	96.88	CD1	72.73%
Upper Colorado	82.35	CD2	89.09%
Little Colorado	23.53	CD3	88.18%
Verde	70.59	CD4	92.73%
Bill Williams	73.53