State Precipitation & Temperature Update for Arizona

Conditions through December 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 seven 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 seven periods for precipitation and temperature are shown below, with tables of the percentile values and descriptive text following the maps. Current update is 1/24/2007. The data are preliminary, and there are some missing precipitation data in the San Pedro watershed.

Precipitation Percentiles by Watershed (through December 2006)

Temperature Percentiles by Climate Division (through December 2006)

SHORT TERM CONDITIONS: 1-6 MONTHS

December precipitation was near or below average everywhere in the state except in the Upper Colorado, Willcox and White Water Draw watersheds. Precipitation in the Bill Williams and San Simon watersheds was at or below the 25^th percentile. Temperatures were near average in the northwest and southeast, slightly above average on the Colorado Plateau, and below average in Maricopa and Pinal counties and the Lower Colorado River. The 3-month period of October through December was also much drier than average, with the driest watersheds across the southern half of the state. Temperatures over the 3-month period were slightly above average for most of the state, and above the 75^th percentile in Maricopa and Pinal counties. The 6-month period, July through December, which includes the wet monsoon, is still above average for the eastern half of the state, and near or below average for the western half of the state. The extreme monsoon moisture in the San Pedro and Willcox basins pushed them up above the 79^th percentile for this period. Temperatures were above average everywhere in the state for the past six months and above the 75^th percentile for the far western and central climate divisions.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	77.78	CD1	55.80
Upper Colorado	52.78	CD2	63.84
Little Colorado	38.89	CD3	56.25
Verde	37.14	CD4	46.43
Bill Williams	19.44	CD5	20.09
Agua Fria	27.78	CD6	26.34
Lower Gila	36.11	CD7	45.09
Salt	27.78
Lower Colorado	33.33
Upper Gila	36.11
Santa Cruz	36.11
San Pedro	38.24
Willcox Playa	43.06
San Simon	25.00
White Water Draw	41.67

DECEMBER 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	51.43	CD1	73.66
Upper Colorado	66.67	CD2	73.21
Little Colorado	44.44	CD3	70.09
Verde	34.29	CD4	67.86
Bill Williams	30.56	CD5	68.30
Agua Fria	16.67	CD6	79.02
Lower Gila	13.89	CD7	70.09
Salt	30.56
Lower Colorado	38.89
Upper Gila	22.22
Santa Cruz	11.11
San Pedro	20.59
Willcox Playa	20.00
San Simon	5.56
White Water Draw	27.78

OCTOBER 2006 - DECEMBER 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	32.35	CD1	76.79
Upper Colorado	55.56	CD2	60.71
Little Colorado	58.33	CD3	69.20
Verde	48.57	CD4	54.02
Bill Williams	22.22	CD5	83.04
Agua Fria	38.89	CD6	78.13
Lower Gila	30.56	CD7	54.46
Salt	44.44
Lower Colorado	55.56
Upper Gila	58.33
Santa Cruz	61.11
San Pedro	79.41
Willcox Playa	85.71
San Simon	27.78
White Water Draw	65.71

JULY 2006 – DECEMBER 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

Precipitation in the 12-month period is well below average across most of the state, except for the southeast watersheds which benefited from an extremely wet monsoon. The southeast and south central division is still the hottest, above the 96^th percentile, and the rest of the state remains above the 77^th percentile.

The two-year period shows only the Upper and Lower Colorado and Virgin River watersheds still above the 50^th percentile. The Santa Cruz and San Simon watersheds in the south central part of the state are extremely dry, below the 20th percentile. For temperature, the southeast climate division remained above the 99^th percentile and most of the state was above the 87^th percentile, while the northwest was the cool spot, in the 75^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	47.06	CD1	77.48
Upper Colorado	19.44	CD2	85.14
Little Colorado	25.00	CD3	88.29
Verde	11.11	CD4	90.99
Bill Williams	5.56	CD5	91.89
Agua Fria	11.11	CD6	93.69
Lower Gila	13.89	CD7	98.20
Salt	11.11
Lower Colorado	19.44
Upper Gila	41.67
Santa Cruz	30.56
San Pedro	47.22
Willcox Playa	55.56
San Simon	5.56
White Water Draw	47.22

JANUARY 2006 – DECEMBER 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	81.82	CD1	75.45
Upper Colorado	54.29	CD2	91.82
Little Colorado	34.29	CD3	88.18
Verde	40.00	CD4	91.82
Bill Williams	25.71	CD5	87.27
Agua Fria	34.29	CD6	93.64
Lower Gila	42.86	CD7	99.09
Salt	34.29
Lower Colorado	60.00
Upper Gila	42.86
Santa Cruz	17.14
San Pedro	37.14
Willcox Playa	42.86
San Simon	11.43
White Water Draw	45.71

JANUARY 2005 – DECEMBER 2006 (24-month): percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

LONG TERM CONDITIONS: 36-48 MONTHS

The 36-month precipitation is well above average in the northern and western watersheds and below average in the south central watersheds and the Colorado Plateau. The rest of the state is near or above average. The Santa Cruz and San Simon watersheds continue to be the driest. Gila county moved up above the 95^th percentile for temperature, and the coolest area is still the northwest in the 76^th percentile.

The 48-month precipitation is still split across the state with the eastern half drier than average and the western half wetter than average. The central watersheds remain near normal. Temperatures are above the 97^th percentile for most of the southern half of the state. The Lower Colorado River divisions are slightly cooler than the central or eastern divisions, but all divisions remain above the 77^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	90.62	CD1	76.15
Upper Colorado	73.53	CD2	90.83
Little Colorado	38.24	CD3	88.99
Verde	55.88	CD4	95.41
Bill Williams	55.88	CD5	88.07
Agua Fria	47.06	CD6	92.66
Lower Gila	58.82	CD7	100.00
Salt	44.12
Lower Colorado	76.47
Upper Gila	44.12
Santa Cruz	8.82
San Pedro	44.12
Willcox Playa	47.06
San Simon	14.71
White Water Draw	50.00

JANUARY 2004 – DECEMBER 2006 (36-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	-99.99	CD1	77.78
Upper Colorado	69.70	CD2	92.59
Little Colorado	18.18	CD3	94.44
Verde	54.55	CD4	98.15
Bill Williams	51.52	CD5	91.20
Agua Fria	45.45	CD6	97.22
Lower Gila	60.61	CD7	100.00
Salt	36.36
Lower Colorado	69.70
Upper Gila	21.21
Santa Cruz	15.15
San Pedro