State Precipitation & Temperature Update for Arizona

Conditions through November 2010

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 12/22/2010. The data are preliminary.

Precipitation Percentiles by Watershed (through November 2010)

Temperature Percentiles by Climate Division (through November 2010)

SHORT TERM CONDITIONS: 1-6 MONTHS

November was slightly drier than normal across the northern half of the state, but was extremely dry across the southern half. Only a few storms moved through the state and they tracked across the north. November temperatures were near average in Mohave, Maricopa and Pinal counties, warmer than average in Yuma and La Paz counties, and colder than average in the other counties. The cold air from the cold fronts penetrated to the southern border, but the moisture remained in the northern half of Arizona. The three month period was similar to November, with much drier than average conditions across the southern watersheds. The upper Colorado and Verde basins were wetter than average, Bill Williams and Salt River basins were near average, and the Little Colorado was again drier than average. Temperatures in the three-month period were warmer than average in all counties, but the most unseasonably warm temperatures were along the lower Colorado River in western Arizona, and in Maricopa and Pinal counties. The six-month period, which includes the monsoon, was wetter than average in the northern half of the state and near average or drier than average across southern Arizona. The driest basins included the San Simon, Santa Cruz, Agua Fria and Bill Williams, all below the 25^th percentile. Six month temperatures were extremely warm, above the 75^th percentile in all counties, and above the 85^th percentile over the southern half of Arizona.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	20.51	CD1	59.91
Upper Colorado	27.50	CD2	33.19
Little Colorado	30.00	CD3	37.50
Verde	40.00	CD4	51.29
Bill Williams	35.00	CD5	60.34
Agua Fria	30.00	CD6	42.67
Lower Gila	20.00	CD7	28.02
Salt	27.50
Lower Colorado	11.25
Upper Gila	10.00
Santa Cruz	12.50
San Pedro	6.25
Willcox Playa	12.82
San Simon	15.00
White Water Draw	12.50

NOVEMBER 2010: 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	63.16	CD1	85.22
Upper Colorado	70.00	CD2	75.00
Little Colorado	40.00	CD3	62.93
Verde	62.50	CD4	82.33
Bill Williams	50.00	CD5	85.34
Agua Fria	15.00	CD6	85.78
Lower Gila	22.50	CD7	68.10
Salt	47.50
Lower Colorado	25.00
Upper Gila	22.50
Santa Cruz	25.00
San Pedro	15.00
Willcox Playa	28.21
San Simon	22.50
White Water Draw	22.50

SEPTEMBER 2010 - NOVEMBER 2010 (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	39.47	CD1	78.26
Upper Colorado	80.00	CD2	84.48
Little Colorado	82.50	CD3	75.43
Verde	60.00	CD4	79.74
Bill Williams	20.00	CD5	87.07
Agua Fria	17.50	CD6	93.10
Lower Gila	60.00	CD7	91.38
Salt	67.50
Lower Colorado	50.00
Upper Gila	55.00
Santa Cruz	17.50
San Pedro	50.00
Willcox Playa	46.15
San Simon	2.50
White Water Draw	51.28

JUNE 2010 – NOVEMBER 2010 (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 12-month period remains the wettest interval with 12 watersheds above the 64^th percentile, eight watersheds above the 76^th percentile, and the upper Colorado still above the 92^nd percentile. The wet conditions still reflect the wet El Niño winter last year and the relatively wet monsoon. Temperatures are generally near average, slightly warmer in some counties and slightly cooler in others. Only Maricopa and Pinal counties are above the 75^th percentile.

The 24-month period still has significant variability from basin to basin. Three basins, the upper Colorado, Salt and lower Gila are wetter than average; two basins, the San Simon and Santa Cruz, are much drier than average; two basins, the Little Colorado and lower Colorado, are near average and the other eight are slightly drier than average. Temperatures for the 24-month period continue to be warmer than average in all counties, but the warmest temperatures are in the southern half of the state, particularly Maricopa and Pinal counties.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	59.46	CD1	66.96
Upper Colorado	92.31	CD2	38.70
Little Colorado	82.05	CD3	50.87
Verde	76.92	CD4	55.22
Bill Williams	64.10	CD5	65.22
Agua Fria	71.79	CD6	75.65
Lower Gila	82.05	CD7	58.26
Salt	87.18
Lower Colorado	79.49
Upper Gila	76.92
Santa Cruz	51.28
San Pedro	82.05
Willcox Playa	66.67
San Simon	41.03
White Water Draw	64.10

DECEMBER 2010 – NOVEMBER 2010 (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	27.78	CD1	69.30
Upper Colorado	73.68	CD2	61.40
Little Colorado	47.37	CD3	77.19
Verde	34.21	CD4	69.30
Bill Williams	28.95	CD5	80.70
Agua Fria	31.58	CD6	92.11
Lower Gila	68.42	CD7	82.89
Salt	71.05
Lower Colorado	52.63
Upper Gila	34.21
Santa Cruz	18.42
San Pedro	39.47
Willcox Playa	31.58
San Simon	15.79
White Water Draw	26.32

DECEMBER 2009 – NOVEMBER 2010 (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 period is now the wettest long-term interval, with four watersheds wetter than average, four drier than average and seven near average. The driest watersheds are the Virgin at the 23^rd percentile, and the Santa Cruz, Willcox Playa and White Water Draw between the 32^nd and 36^th percentiles. The wettest watershed is the lower Gila at the 81^st percentile. Temperatures for the three year period continue to be warmer than average, with the northern counties between the 66^th and 68^th percentiles, and the central and southern counties above the 76^th percentile.

The 48-month period is still the driest interval with two watersheds, the upper Colorado and lower Gila, wetter than average, and two watersheds, Salt and upper Gila near average. Eleven watersheds are below the 37^th percentile, and six of those are below the 25th percentile. The Virgin and Bill Williams basins are below the 14^th percentile. The 48-month temperatures are still the warmest interval with the southern counties above the 85^th percentile, and the northern counties above the 73^rd percentile. Maricopa and Pinal counties are at the 98^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	22.86	CD1	68.14
Upper Colorado	72.97	CD2	66.37
Little Colorado	54.05	CD3	76.99
Verde	45.95	CD4	52.65
Bill Williams	43.24	CD5	83.19
Agua Fria	43.24	CD6	93.81
Lower Gila	81.08	CD7	77.43
Salt	67.57
Lower Colorado	56.76
Upper Gila	62.16
Santa Cruz	35.14
San Pedro	51.35
Willcox Playa	32.43
San Simon	45.95
White Water Draw	32.43

DECEMBER 2008 – NOVEMBER 2010 (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	6.06	CD1	73.21
Upper Colorado	61.11	CD2	81.70
Little Colorado	36.11	CD3	83.04
Verde	19.44	CD4	74.11
Bill Williams	13.89	CD5	86.61
Agua Fria	19.44	CD6	98.21
Lower Gila	75.00	CD7	85.27
Salt	58.33
Lower Colorado	30.56
Upper Gila	41.67
Santa Cruz	16.67
San Pedro	36.11
Willcox Playa	30.56
San Simon	25.00
White Water Draw	36.11

DECEMBER 2007 – NOVEMBER 2010 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

December 2010 Arizona Drought Update (based on precipitation data through November 2010)

The following summary describes the heat and dryness across the state for the 1-, 3-, 6-, 12-, 24-, 36-, and 48-month periods.

SUMMARY

November was slightly drier than normal across the northern half of the state, but was extremely dry across the southern half. Only a few storms moved through the state and they tracked across the north. November temperatures were near average in Mohave, Maricopa and Pinal counties, warmer than average in Yuma and La Paz counties, and colder than average in the other counties. The cold air from the cold fronts penetrated to the southern border, but the moisture remained in the northern half of Arizona.

The 3-month period was similar to November, with much drier than average conditions across the southern watersheds. The upper Colorado and Verde basins were wetter than average, Bill Williams and Salt River basins were near average, and the Little Colorado was again drier than average. Temperatures in the three-month period were warmer than average in all counties, but the most unseasonably warm temperatures were along the lower Colorado River in western Arizona, and in Maricopa and Pinal counties.

The 6-month period, which includes the monsoon, was wetter than average in the northern half of the state and near average or drier than average across southern Arizona. The driest basins included the San Simon, Santa Cruz, Agua Fria and Bill Williams, all below the 25^th percentile. Six month temperatures were extremely warm, above the 75^th percentile in all counties, and above the 85^th percentile over the southern half of Arizona.

The 12-month period remains the wettest interval with 12 watersheds above the 64^th percentile, eight watersheds above the 76^th percentile, and the upper Colorado still above the 92^nd percentile. The wet conditions still reflect the wet El Niño winter last year and the relatively wet monsoon. Temperatures are generally near average, slightly warmer in some counties and slightly cooler in others. Only Maricopa and Pinal counties are above the 75^th percentile.

The 24-month period still has significant variability from basin to basin. Three basins, the upper Colorado, Salt and lower Gila are wetter than average; two basins, the San Simon and Santa Cruz, are much drier than average; two basins, the Little Colorado and lower Colorado, are near average and the other eight are slightly drier than average. Temperatures for the 24-month period continue to be warmer than average in all counties, but the warmest temperatures are in the southern half of the state, particularly Maricopa and Pinal counties.

The 36-month period is now the wettest long-term interval, with four watersheds wetter than average, four drier than average and seven near average. The driest watersheds are the Virgin at the 23^rd percentile, and the Santa Cruz, Willcox Playa and White Water Draw between the 32^nd and 36^th percentiles. The wettest watershed is the lower Gila at the 81^st percentile. Temperatures for the three year period continue to be warmer than average, with the northern counties between the 66^th and 68^th percentiles, and the central and southern counties above the 76^th percentile.

The 48-month period is still the driest interval with two watersheds, the upper Colorado and lower Gila, wetter than average, and two watersheds, Salt and upper Gila near average. Eleven watersheds are below the 37^th percentile, and six of those are below the 25th percentile. The Virgin and Bill Williams basins are below the 14^th percentile. The 48-month temperatures are still the warmest interval with the southern counties above the 85^th percentile, and the northern counties above the 73^rd percentile. Maricopa and Pinal counties are at the 98^th percentile.