State Precipitation & Temperature Update for Arizona

Conditions through November 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 1/23/2012. The data are preliminary.

Precipitation Percentiles by Watershed (through November 2011)

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Temperature Percentiles by Climate Division (through November 2011)

SHORT TERM CONDITIONS: 1-6 MONTHS

November was wetter than average in 12 watersheds, near average in 2, and drier than average in 1. The wettest were San Simon, Lower Colorado and Lower Gila, with 95%, 90% and 88% of average respectively, while the dry watershed was the Virgin at 32% of average precipitation. November is the first really wet month we have had since August. Temperatures were near average in most counties, with slightly colder than average temperatures in Yavapai County and slightly warmer than average in Maricopa and Pinal counties. The three month precipitation was wetter than average in the northern and southern watersheds, but near or slightly drier than average in the central watersheds. The upper Gila and Agua Fria were the driest at 36.5% of average. Three month temperatures were warmer than average in all counties, with the western and southern counties the warmest, above the 76^th percentile. Six month precipitation was near or drier than average in all watersheds, with the driest conditions in the Bill Williams, Agua Fria and San Simon watersheds, at the 15^th, 17^th, and 10^th percentiles, respectively. Six month temperatures were all well above average with every county, except Mohave, above the 77^th percentile. Mohave was at the 71^st percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	32.50	CD1	47.01
Upper Colorado	63.41	CD2	49.57
Little Colorado	51.22	CD3	39.32
Verde	68.29	CD4	42.31
Bill Williams	68.29	CD5	55.56
Agua Fria	63.41	CD6	64.53
Lower Gila	87.80	CD7	52.14
Salt	73.17
Lower Colorado	90.24
Upper Gila	68.29
Santa Cruz	78.05
San Pedro	56.10
Willcox Playa	67.50
San Simon	95.12
White Water Draw	78.05

NOVEMBER 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	61.54	CD1	76.29
Upper Colorado	60.98	CD2	61.97
Little Colorado	65.85	CD3	70.51
Verde	51.22	CD4	63.25
Bill Williams	53.66	CD5	90.60
Agua Fria	36.59	CD6	92.31
Lower Gila	58.54	CD7	81.62
Salt	43.90
Lower Colorado	48.78
Upper Gila	36.59
Santa Cruz	63.41
San Pedro	48.78
Willcox Playa	52.50
San Simon	60.98
White Water Draw	60.98

SEPTEMBER 2011 - NOVEMBER 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	46.15	CD1	71.55
Upper Colorado	43.90	CD2	77.35
Little Colorado	46.34	CD3	85.47
Verde	31.71	CD4	94.02
Bill Williams	14.63	CD5	91.45
Agua Fria	17.07	CD6	95.73
Lower Gila	48.78	CD7	95.73
Salt	34.15
Lower Colorado	34.15
Upper Gila	29.27
Santa Cruz	26.83
San Pedro	51.22
Willcox Playa	40.00
San Simon	9.76
White Water Draw	40.00

JUNE 2011 – NOVEMBER 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 is still the driest short-term period, with only one watershed, the upper Colorado, above the 40^th percentile. Fourteen watersheds are below the 38^th percentile, and eleven of those are below the 23^rd percentile and eight of those are below the 13^th percentile. Temperatures were much warmer than average in the central and southern counties, all above the 81^st percentile.

The 24-month period continues as the wettest long-term interval with two watersheds in northern Arizona above the 61^st percentile, and four below the 24^th percentile. The others are near or slightly drier than average. Temperatures for the last 2 years have been warmer than average, but the warmest are the southern counties between the 86^th and 88^th percentiles. This is significantly cooler than the 3 month interval. The northern counties are near average for temperature, making this the coolest long-term interval.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	28.95	CD1	60.34
Upper Colorado	55.00	CD2	64.66
Little Colorado	37.50	CD3	81.47
Verde	30.00	CD4	87.07
Bill Williams	22.50	CD5	81.03
Agua Fria	12.50	CD6	88.79
Lower Gila	20.00	CD7	92.24
Salt	15.00
Lower Colorado	25.00
Upper Gila	5.00
Santa Cruz	2.50
San Pedro	10.00
Willcox Playa	7.50
San Simon	5.00
White Water Draw	7.50

DECEMBER 2010 - NOVEMBER 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	35.14	CD1	60.00
Upper Colorado	92.31	CD2	52.17
Little Colorado	61.54	CD3	75.65
Verde	48.72	CD4	78.26
Bill Williams	41.03	CD5	73.91
Agua Fria	33.33	CD6	86.09
Lower Gila	58.97	CD7	87.83
Salt	56.41
Lower Colorado	57.69
Upper Gila	30.77
Santa Cruz	7.69
San Pedro	46.15
Willcox Playa	17.95
San Simon	10.26
White Water Draw	23.08

DECEMBER 2009 - NOVEMBER 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 remains the driest long-term interval, and the upper Colorado watershed is still the wettest watersheds, above the 63^rd percentile, while three others are between the 42^nd and 47^th percentiles. Nine watersheds are below the 16^th percentile and four of those are below the 14^th percentile. Temperatures for the three year period were warmer than average everywhere, with the four northern counties between the 65^th and 72^nd percentiles, and the southern counties above the 78^th percentile.

The 48-month period remains a patchwork of wet and dry watersheds. Two watersheds, the Upper Colorado in the north, and Lower Gila in the southwest, continue to be wetter than average (above the 64^th percentile) and two (San Simon and Santa Cruz) remain much drier than average (below the 3^rd percentile. The 48 month period is the warmest long term period, with 5 counties slightly warmer than average and the 10 southern counties all much warmer than average, above the 78^th percentile. Maricopa and Pinal counties are above the 97^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	25.00	CD1	65.79
Upper Colorado	63.16	CD2	71.05
Little Colorado	47.37	CD3	78.95
Verde	28.95	CD4	78.51
Bill Williams	15.79	CD5	82.46
Agua Fria	15.79	CD6	94.74
Lower Gila	42.11	CD7	92.98
Salt	47.37
Lower Colorado	34.21
Upper Gila	15.79
Santa Cruz	2.63
San Pedro	15.79
Willcox Playa	13.16
San Simon	2.63
White Water Draw	13.16

DECEMBER 2008 - NOVEMBER 2011 (36-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	14.71	CD1	66.37
Upper Colorado	75.68	CD2	68.14
Little Colorado	54.05	CD3	78.76
Verde	24.32	CD4	69.47
Bill Williams	21.62	CD5	83.19
Agua Fria	18.92	CD6	97.35
Lower Gila	64.86	CD7	86.28
Salt	56.76
Lower Colorado	35.14
Upper Gila	29.73
Santa Cruz	8.11
San Pedro	29.73
Willcox Playa	18.92
San Simon	21.62
White Water Draw	18.92

DECEMBER 2007 - NOVEMBER 2011 (48-month): percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

December 2011 Arizona Drought Update (based on precipitation data through November 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

November was wetter than average in 12 watersheds, near average in 2, and drier than average in 1. The wettest were San Simon, Lower Colorado and Lower Gila, with 95%, 90% and 88% of average respectively, while the dry watershed was the Virgin at 32% of average precipitation. November is the first really wet month we have had since August. Temperatures were near average in most counties, with slightly colder than average temperatures in Yavapai County and slightly warmer than average in Maricopa and Pinal counties.

The 3-month period was wetter than average in the northern and southern watersheds, but near or slightly drier than average in the central watersheds. The upper Gila and Agua Fria were the driest at 36.5% of average. Three month temperatures were warmer than average in all counties, with the western and southern counties the warmest, above the 76^th percentile.

The 6-month period was near or drier than average in all watersheds, with the driest conditions in the Bill Williams, Agua Fria and San Simon watersheds, at the 15^th, 17^th, and 10^th percentiles, respectively. Six month temperatures were all well above average with every county, except Mohave, above the 77^th percentile. Mohave was at the 71^st percentile.

The 12-month period is still the driest short-term period, with only one watershed, the upper Colorado, above the 40^th percentile. Fourteen watersheds are below the 38^th percentile, and eleven of those are below the 23^rd percentile and eight of those are below the 13^th percentile. Temperatures were much warmer than average in the central and southern counties, all above the 81^st percentile.

The 24-month period continues as the wettest long-term interval with two watersheds in northern Arizona above the 61^st percentile, and four below the 24^th percentile. The others are near or slightly drier than average. Temperatures for the last 2 years have been warmer than average, but the warmest are the southern counties between the 86^th and 88^th percentiles. This is significantly cooler than the 3 month interval. The northern counties are near average for temperature, making this the coolest long-term interval.

The 36-month period remains the driest long-term interval, and the upper Colorado watershed is still the wettest watersheds, above the 63^rd percentile, while three others are between the 42^nd and 47^th percentiles. Nine watersheds are below the 16^th percentile and four of those are below the 14^th percentile. Temperatures for the three year period were warmer than average everywhere, with the four northern counties between the 65^th and 72^nd percentiles, and the southern counties above the 78^th percentile.

The 48-month period remains a patchwork of wet and dry watersheds. Two watersheds, the Upper Colorado in the north, and Lower Gila in the southwest, continue to be wetter than average (above the 64^th percentile) and two (San Simon and Santa Cruz) remain much drier than average (below the 3^rd percentile. The 48 month period is the warmest long term period, with 5 counties slightly warmer than average and the 10 southern counties all much warmer than average, above the 78^th percentile. Maricopa and Pinal counties are above the 97^th percentile.