State Precipitation & Temperature Update for Arizona

Conditions through July 2011

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. The percentiles have shifted to reflect the percentile categories used in the National Drought Monitor. Current update is 8/22/2011. The data are preliminary.

Precipitation Percentiles by Watershed (through July 2011)

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Temperature Percentiles by Climate Division (through July 2011)

SHORT TERM CONDITIONS: 1-6 MONTHS

July was a relatively wet month, except for the counties that need it most, in the southeast. The monsoon activity began July 3^rd, and was fairly constant through the month, but the thunderstorms here highly localized. Some locations were quite wet, while nearby areas were completely dry. Northern Arizona and the higher elevations along the Mogollon Rim fared well, as did the southwestern watersheds. Santa Cruz and San Simon watersheds missed out on most of the rainfall. July temperatures were near average in the northeast, and much warmer than average in the southwest. The three month period remains the wettest short term interval, with seven watersheds near or wetter than average. In the south, all watersheds except the San Pedro are below the 20^th percentile. Temperatures in the 3-month period were very near average, except Coconino, Apache and Navajo counties, which were cooler than average. The six-month period also continues to be the driest short-term interval with ten watersheds below the 25^th percentile. Five watersheds in the southeast corner of the state are below the 8^th percentile, only a slight improvement from last month. Only the Upper Colorado watershed is wetter than average. Six month temperatures were slightly warmer than average in four western counties, slightly cooler than average in three northeast counties (Coconino, Apache and Navajo) and above the 78^th percentile in the seven southeast counties.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	85.00	CD1	78.63
Upper Colorado	85.37	CD2	58.97
Little Colorado	68.29	CD3	74.36
Verde	53.66	CD4	56.84
Bill Williams	43.90	CD5	86.32
Agua Fria	43.90	CD6	89.74
Lower Gila	68.29	CD7	71.79
Salt	80.49
Lower Colorado	82.93
Upper Gila	46.34
Santa Cruz	21.95
San Pedro	80.49
Willcox Playa	48.78
San Simon	9.76
White Water Draw	35.00

JULY 2011: 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	75.00	CD1	59.91
Upper Colorado	73.17	CD2	37.61
Little Colorado	48.78	CD3	50.85
Verde	36.59	CD4	60.68
Bill Williams	29.27	CD5	59.40
Agua Fria	31.71	CD6	65.38
Lower Gila	56.10	CD7	56.41
Salt	68.29
Lower Colorado	68.29
Upper Gila	29.27
Santa Cruz	9.76
San Pedro	60.98
Willcox Playa	19.51
San Simon	4.88
White Water Draw	20.00

MAY 2011 - JULY 2011 (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	27.50	CD1	52.59
Upper Colorado	73.17	CD2	35.47
Little Colorado	34.15	CD3	56.41
Verde	24.39	CD4	71.79
Bill Williams	17.07	CD5	56.84
Agua Fria	12.20	CD6	65.81
Lower Gila	31.71	CD7	78.63
Salt	21.95
Lower Colorado	46.34
Upper Gila	7.32
Santa Cruz	2.44
San Pedro	17.07
Willcox Playa	5.00
San Simon	2.44
White Water Draw	5.00

FEBRUARY 2011 – JULY 2011 (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 has only one watershed wetter than average, six between the 27^th and 35^th percentiles, one at the 20^th percentile, and seven at or below the 10^th percentile. San Simon and Santa Cruz are at the 2.5^th percentile. Temperatures were warmer than average, with three climate divisions in northern Arizona below the 73^rd percentile, and the other four climate divisions between the 75^th and 88^th percentiles.

The 24-month period is the wettest long-term period with the Upper Colorado at the 69^th percentile, three other watersheds above the 43^rd percentile, eleven watersheds drier than average with six of those below the 21^st percentile. Temperatures in Coconino, Apache and Navajo counties were near average while the rest of the counties were all above the 62^nd percentile. The seven southeastern counties were at the 82^nd percentile, while Maricopa and Pinal counties were at the 84^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	32.43	CD1	62.07
Upper Colorado	75.00	CD2	56.03
Little Colorado	32.50	CD3	72.41
Verde	35.00	CD4	82.76
Bill Williams	35.00	CD5	75.86
Agua Fria	10.00	CD6	84.91
Lower Gila	20.00	CD7	87.93
Salt	30.00
Lower Colorado	27.50
Upper Gila	7.50
Santa Cruz	2.50
San Pedro	10.00
Willcox Playa	5.13
San Simon	2.50
White Water Draw	7.50

AUGUST 2010 – JULY 2011 (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	37.84	CD1	62.61
Upper Colorado	69.23	CD2	43.48
Little Colorado	33.33	CD3	72.17
Verde	30.77	CD4	71.30
Bill Williams	20.51	CD5	69.57
Agua Fria	17.95	CD6	84.35
Lower Gila	53.85	CD7	81.74
Salt	43.59
Lower Colorado	53.85
Upper Gila	25.64
Santa Cruz	5.13
San Pedro	28.21
Willcox Playa	12.82
San Simon	7.69
White Water Draw	17.95

AUGUST 2009 – JULY 2011 (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 driest long-term interval, with four watersheds near or slightly wetter than average, the other eleven watersheds below the 23^rd percentile, and five of those below the 14^th percentile. Temperatures for the three year period were warmer than average with five counties between the 66^th and 71^st percentiles, the eight counties in the southeast between the 78^th and 84^th percentiles, and Maricopa and Pinal counties above the 95^th percentile.

The 48-month period has two watersheds (Upper Colorado and Lower Gila) wetter than average and two (Little Colorado and Salt) near average. The Lower Colorado and Upper Gila are slightly drier than average, while the other nine watersheds are below the 25^th percentile. Temperatures for the four year period were warmer than average in all counties, with Maricopa and Pinal counties above the 98^th percentile. The seven southeastern counties are at the 83^rd percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	18.92	CD1	66.67
Upper Colorado	63.16	CD2	70.18
Little Colorado	23.68	CD3	78.95
Verde	21.05	CD4	66.67
Bill Williams	18.42	CD5	81.58
Agua Fria	15.79	CD6	95.61
Lower Gila	52.63	CD7	83.33
Salt	47.37
Lower Colorado	52.63
Upper Gila	15.79
Santa Cruz	2.63
San Pedro	13.16
Willcox Playa	7.89
San Simon	5.26
White Water Draw	10.53

AUGUST 2008 – JULY 2011 (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	11.43	CD1	66.67
Upper Colorado	70.27	CD2	71.24
Little Colorado	40.54	CD3	81.42
Verde	24.32	CD4	71.24
Bill Williams	21.62	CD5	82.30
Agua Fria	18.92	CD6	98.23
Lower Gila	67.57	CD7	88.50
Salt	56.76
Lower Colorado	35.14
Upper Gila	27.03
Santa Cruz	5.41
San Pedro	16.22
Willcox Playa	18.92
San Simon	13.51
White Water Draw	24.32

AUGUST 2007 – JULY 2011 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

August 2011 Arizona Drought Update (based on precipitation data through July 2011)

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

SUMMARY

July was a relatively wet month, except for the counties that need it most, in the southeast. The monsoon activity began July 3^rd, and was fairly constant through the month, but the thunderstorms here highly localized. Some locations were quite wet, while nearby areas were completely dry. Northern Arizona and the higher elevations along the Mogollon Rim fared well, as did the southwestern watersheds. Santa Cruz and San Simon watersheds missed out on most of the rainfall. July temperatures were near average in the northeast, and much warmer than average in the southwest.

The 3-month period remains the wettest short term interval, with seven watersheds near or wetter than average. In the south, all watersheds except the San Pedro are below the 20^th percentile. Temperatures in the 3-month period were very near average, except Coconino, Apache and Navajo counties, which were cooler than average.

The 6-month period also continues to be the driest short-term interval with ten watersheds below the 25^th percentile. Five watersheds in the southeast corner of the state are below the 8^th percentile, only a slight improvement from last month. Only the Upper Colorado watershed is wetter than average. Six month temperatures were slightly warmer than average in four western counties, slightly cooler than average in three northeast counties (Coconino, Apache and Navajo) and above the 78^th percentile in the seven southeast counties.

The 12-month period has only one watershed wetter than average, six between the 27^th and 35^th percentiles, one at the 20^th percentile, and seven at or below the 10^th percentile. San Simon and Santa Cruz are at the 2.5^th percentile. Temperatures were warmer than average, with three climate divisions in northern Arizona below the 73^rd percentile, and the other four climate divisions between the 75^th and 88^th percentiles.

The 24-month period is the wettest long-term period with the Upper Colorado at the 69^th percentile, three other watersheds above the 43^rd percentile, eleven watersheds drier than average with six of those below the 21^st percentile. Temperatures in Coconino, Apache and Navajo counties were near average while the rest of the counties were all above the 62^nd percentile. The seven southeastern counties were at the 82^nd percentile, while Maricopa and Pinal counties were at the 84^th percentile.

The 36-month period is now the driest long-term interval, with four watersheds near or slightly wetter than average, the other eleven watersheds below the 23^rd percentile, and five of those below the 14^th percentile. Temperatures for the three year period were warmer than average with five counties between the 66^th and 71^st percentiles, the eight counties in the southeast between the 78^th and 84^th percentiles, and Maricopa and Pinal counties above the 95^th percentile.

The 48-month period has two watersheds (Upper Colorado and Lower Gila) wetter than average and two (Little Colorado and Salt) near average. The Lower Colorado and Upper Gila are slightly drier than average, while the other nine watersheds are below the 25^th percentile. Temperatures for the four year period were warmer than average in all counties, with Maricopa and Pinal counties above the 98^th percentile. The seven southeastern counties are at the 83^rd percentile.