State Precipitation & Temperature Update for Arizona

Conditions through June 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 7/29/2011. The data are preliminary.

Precipitation Percentiles by Watershed (through June 2011)

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Temperature Percentiles by Climate Division (through June 2011)

SHORT TERM CONDITIONS: 1-6 MONTHS

June was a very dry month statewide, with 11 watersheds below the 24^th percentile. Only the lower Colorado was wetter than average, at the 71^st percentile. June temperatures were slightly warmer than average in 7 counties, and much warmer than average in 5 counties. The dry and relatively cool weather was due to the subtropical high pressure system remaining in place east of New Mexico. The three month period is now the wettest short term interval, with four watersheds near or wetter than average. Temperatures in the 3-month period were near average in seven counties and slightly warmer than average in three others. Even the southeastern counties were below the 77^th percentile. The six-month period is now the driest short term interval with thirteen watersheds below the 18^th percentile. Five watersheds in the southeast corner of the state are below the 5^th percentile. The six month period includes the winter and spring, both of which were exceptionally dry in the southern and southeastern parts of the state. Six month temperatures were only slightly warmer than average in nine counties and near average in six counties. The relatively cool temperatures are a result of numerous cold fronts that moved through the state. Unfortunately, most of the fronts had no moisture to generate precipitation.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	13.75	CD1	63.25
Upper Colorado	3.66	CD2	64.10
Little Colorado	12.20	CD3	66.24
Verde	7.32	CD4	79.49
Bill Williams	18.29	CD5	65.81
Agua Fria	19.51	CD6	77.78
Lower Gila	20.73	CD7	88.03
Salt	17.07
Lower Colorado	70.73
Upper Gila	36.59
Santa Cruz	9.76
San Pedro	23.17
Willcox Playa	34.15
San Simon	20.73
White Water Draw	31.71

JUNE 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	15.00	CD1	59.48
Upper Colorado	58.54	CD2	42.74
Little Colorado	29.27	CD3	48.29
Verde	29.27	CD4	72.65
Bill Williams	39.02	CD5	56.41
Agua Fria	31.71	CD6	65.81
Lower Gila	60.98	CD7	76.92
Salt	31.71
Lower Colorado	59.76
Upper Gila	31.71
Santa Cruz	17.07
San Pedro	7.32
Willcox Playa	4.88
San Simon	53.66
White Water Draw	9.76

APRIL 2011 - JUNE 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	14.10	CD1	61.21
Upper Colorado	41.46	CD2	48.72
Little Colorado	7.50	CD3	46.58
Verde	17.07	CD4	68.38
Bill Williams	14.63	CD5	52.56
Agua Fria	14.63	CD6	67.52
Lower Gila	12.20	CD7	69.23
Salt	12.20
Lower Colorado	34.15
Upper Gila	4.88
Santa Cruz	4.88
San Pedro	2.44
Willcox Playa	2.50
San Simon	12.20
White Water Draw	2.50

JANUARY 2011 – JUNE 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 two watersheds near or wetter than average, four slightly drier than normal and nine much drier than normal, at or below the 25^th percentile. San Simon is at the 5^th percentile. Temperatures were much warmer than average, between the 71^st and 88^th percentile in all counties.

The 24-month period is the driest long-term period with six watersheds slightly drier than normal, below the 34^th percentile and six others much drier than normal, below the 18^th percentile. The seven northern and western counties were slightly warmer than normal and the southern and eastern counties were much warmer than normal, especially Maricopa and Pinal counties, above the 87^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	28.95	CD1	71.55
Upper Colorado	70.00	CD2	75.00
Little Colorado	55.00	CD3	73.28
Verde	40.00	CD4	81.90
Bill Williams	25.00	CD5	76.72
Agua Fria	12.50	CD6	86.21
Lower Gila	25.00	CD7	87.93
Salt	35.00
Lower Colorado	32.50
Upper Gila	20.00
Santa Cruz	7.50
San Pedro	10.00
Willcox Playa	12.82
San Simon	5.00
White Water Draw	17.95

JULY 2010 – JUNE 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	29.73	CD1	66.96
Upper Colorado	69.23	CD2	55.65
Little Colorado	25.64	CD3	71.30
Verde	25.64	CD4	75.65
Bill Williams	25.64	CD5	73.91
Agua Fria	17.95	CD6	87.83
Lower Gila	58.97	CD7	84.35
Salt	33.33
Lower Colorado	46.15
Upper Gila	25.64
Santa Cruz	15.38
San Pedro	17.95
Willcox Playa	12.82
San Simon	7.69
White Water Draw	12.82

JULY 2009 – JUNE 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 still mixed with three northern and central watersheds near average, six northern and central watersheds drier than average, and six southern watersheds much drier than average. Temperatures for the three year period were warmer than average with five counties just above the 74^th percentile, eight counties between the 76^th and 84^th percentiles, and Maricopa and Pinal counties above the 97^th percentile.

The 48-month period is the wettest long term period with three watersheds wetter than average and two near average. Four others are slightly drier than average and six are below the 19^th percentile. Temperatures for the four year period were much warmer than average in all counties, with Maricopa and Pinal counties above the 98^th percentile. Only Mohave and Gila counties are below the 79^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	13.89	CD1	70.18
Upper Colorado	57.89	CD2	73.68
Little Colorado	31.58	CD3	76.32
Verde	26.32	CD4	67.54
Bill Williams	26.32	CD5	83.33
Agua Fria	18.42	CD6	97.37
Lower Gila	68.42	CD7	82.46
Salt	50.00
Lower Colorado	50.00
Upper Gila	31.58
Santa Cruz	10.53
San Pedro	28.95
Willcox Playa	21.05
San Simon	15.79
White Water Draw	18.42

JULY 2008 – JUNE 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	8.57	CD1	67.11
Upper Colorado	67.57	CD2	79.65
Little Colorado	40.54	CD3	80.53
Verde	27.03	CD4	71.68
Bill Williams	27.03	CD5	82.30
Agua Fria	18.92	CD6	98.23
Lower Gila	75.68	CD7	90.27
Salt	64.86
Lower Colorado	43.24
Upper Gila	35.14
Santa Cruz	16.22
San Pedro	16.22
Willcox Playa	16.22
San Simon	32.43
White Water Draw	21.62

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

July 2011 Arizona Drought Update (based on precipitation data through June 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

June was a very dry month statewide, with 11 watersheds below the 24^th percentile. Only the lower Colorado was wetter than average, at the 71^st percentile. June temperatures were slightly warmer than average in 7 counties, and much warmer than average in 5 counties. The dry and relatively cool weather was due to the subtropical high pressure system remaining in place east of New Mexico.

The 3-month period period is now the wettest short term interval, with four watersheds near or wetter than average. Temperatures in the 3-month period were near average in seven counties and slightly warmer than average in three others. Even the southeastern counties were below the 77^th percentile. The six-month period is now the driest short term interval with thirteen watersheds below the 18^th percentile. Five watersheds in the southeast corner of the state are below the 5^th percentile.

The 6-month period includes the winter and spring, both of which were exceptionally dry in the southern and southeastern parts of the state. Six month temperatures were only slightly warmer than average in nine counties and near average in six counties. The relatively cool temperatures are a result of numerous cold fronts that moved through the state. Unfortunately, most of the fronts had no moisture to generate precipitation.

The 12-month period has only two watersheds near or wetter than average, four slightly drier than normal and nine much drier than normal, at or below the 25^th percentile. San Simon is at the 5^th percentile. Temperatures were much warmer than average, between the 71^st and 88^th percentile in all counties.

The 24-month period is the driest long-term period with six watersheds slightly drier than normal, below the 34^th percentile and six others much drier than normal, below the 18^th percentile. The seven northern and western counties were slightly warmer than normal and the southern and eastern counties were much warmer than normal, especially Maricopa and Pinal counties, above the 87^th percentile.

The 36-month period is still mixed with three northern and central watersheds near average, six northern and central watersheds drier than average, and six southern watersheds much drier than average. Temperatures for the three year period were warmer than average with five counties just above the 74^th percentile, eight counties between the 76^th and 84^th percentiles, and Maricopa and Pinal counties above the 97^th percentile.

The 48-month period is the wettest long term period with three watersheds wetter than average and two near average. Four others are slightly drier than average and six are below the 19^th percentile. Temperatures for the four year period were much warmer than average in all counties, with Maricopa and Pinal counties above the 98^th percentile. Only Mohave and Gila counties are below the 79^th percentile.