State Precipitation & Temperature Update for Arizona

Conditions through November 2012

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 12/27/2012. The data are preliminary.

Precipitation Percentiles by Watershed (through November 2012)

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Temperature Percentiles by Climate Division (through November 2012)

SHORT TERM CONDITIONS: 1-6 MONTHS

November precipitation was sparse statewide. Only one storm system passed through the state, on the 9^th through the 11^th. The storm even dropped a little snow on Payson, Show Low and Flagstaff, but precipitation totals were well below average, especially in the southeastern watersheds. Temperatures were much warmer than normal statewide, with the hottest conditions in Mohave, Pinal and Maricopa counties, all above the 97^th percentile. The three month period was by far the driest short term period, with eight watersheds below the 20^th percentile and three below the 8^th percentile. During this interval the southern counties fared much better. As is often the case, the driest areas had the warmest temperatures, with all counties except those on the Colorado Plateau above the 89^th percentile. Six month precipitation, essentially summer and fall, was near average in all areas of the state, with only Willcox Playa and White Water Draw drier than average, both below the 18^th percentile. The lower Gila and lower Colorado watersheds received above average precipitation, though much of that was received from very few storms. Six month temperatures were very high with fourteen counties above the 86^th percentile, while Mohave County enjoyed slightly cooler weather, only up to the 80^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	23.81	CD1	98.31
Upper Colorado	23.81	CD2	88.98
Little Colorado	21.43	CD3	93.22
Verde	26.19	CD4	89.83
Bill Williams	33.33	CD5	93.22
Agua Fria	28.57	CD6	97.46
Lower Gila	26.19	CD7	93.22
Salt	21.43
Lower Colorado	23.81
Upper Gila	16.67
Santa Cruz	23.81
San Pedro	30.95
Willcox Playa	21.95
San Simon	35.71
White Water Draw	14.29

November 2012: 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	7.14	CD1	95.73
Upper Colorado	7.14	CD2	84.75
Little Colorado	2.38	CD3	91.53
Verde	19.05	CD4	90.68
Bill Williams	11.90	CD5	97.46
Agua Fria	11.90	CD6	94.92
Lower Gila	52.38	CD7	89.83
Salt	16.67
Lower Colorado	54.76
Upper Gila	14.29
Santa Cruz	28.57
San Pedro	21.43
Willcox Playa	21.95
San Simon	64.29
White Water Draw	21.43

September 2012 - November 2012 (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	33.33	CD1	80.77
Upper Colorado	33.33	CD2	86.44
Little Colorado	30.95	CD3	91.53
Verde	42.86	CD4	97.46
Bill Williams	47.62	CD5	97.46
Agua Fria	47.62	CD6	95.76
Lower Gila	73.81	CD7	96.61
Salt	33.33
Lower Colorado	69.05
Upper Gila	30.95
Santa Cruz	40.48
San Pedro	47.62
Willcox Playa	17.07
San Simon	40.48
White Water Draw	14.63

June 2012 – November 2012 (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 was much drier than average across all watersheds except the southwestern third of Arizona. Six watersheds were above the 20^th percentile, but nine were below. The twelve month period was very warm, with a gradient from southeast to northwest, with Mohave County the relative cool county.

The 24-month period continues to be the driest interval, covering two consecutive La Niña winters and two drier than average monsoons. Four watersheds are at the 25^th percentile while eight are below the 18^th percentile. The 24-month temperatures were very warm with the southern half of the state above the 88^th percentile, and only Mohave County below the 81^st percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	14.63	CD1	82.05
Upper Colorado	14.63	CD2	88.03
Little Colorado	14.63	CD3	89.74
Verde	19.51	CD4	89.74
Bill Williams	26.83	CD5	94.87
Agua Fria	29.27	CD6	94.87
Lower Gila	46.34	CD7	97.44
Salt	12.20
Lower Colorado	39.02
Upper Gila	17.07
Santa Cruz	21.95
San Pedro	17.07
Willcox Playa	12.20
San Simon	31.71
White Water Draw	9.76

December 2011 - November 2012 (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	25.00	CD1	69.83
Upper Colorado	25.00	CD2	81.47
Little Colorado	25.00	CD3	88.79
Verde	17.50	CD4	92.24
Bill Williams	15.00	CD5	91.38
Agua Fria	7.50	CD6	93.10
Lower Gila	17.50	CD7	96.55
Salt	10.00
Lower Colorado	25.00
Upper Gila	7.50
Santa Cruz	2.50
San Pedro	10.00
Willcox Playa	5.00
San Simon	5.00
White Water Draw	7.50

December 2010 – November 2012 (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 continues to be the wettest long term interval, as the two previous dry years are joined by the very wet El Niño winter of 2009-2010. but only the Virgin and Upper Colorado watersheds received greater than normal precipitation. Nine watersheds were below the 30^th percentile, and one was below the 8^th percentile. This reflects the wet El Niño winter of 2010. Eight watersheds were above the 33^rd percentile. Temperatures for the three year period were the coolest of the long term intervals, corresponding to the increased precipitation and winter storms. The northern counties were below the 82^nd percentile, while the warmest counties in southern Arizona were above the 86^h percentile.

The 48-month period was again much drier than normal as three dry years are not balanced with only one wet year. The southeastern watersheds fared the worst, but even central Arizona was dry as the Bill Williams, Agua Fria and Verde watersheds were all below the 16^th percentile. In the south, four watersheds were below the 8^th percentile, and two more were below the 11^th. Temperatures in the south central and southeastern counties were above the 98^th percentile, while Yuma, La Paz, and Gila counties were just above the 85^th percentile. The northern counties were all below the 75^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	58.97	CD1	67.83
Upper Colorado	58.97	CD2	75.65
Little Colorado	51.28	CD3	81.74
Verde	41.03	CD4	86.96
Bill Williams	33.33	CD5	86.09
Agua Fria	25.64	CD6	92.17
Lower Gila	51.28	CD7	94.78
Salt	41.03
Lower Colorado	46.15
Upper Gila	17.95
Santa Cruz	5.13
San Pedro	25.64
Willcox Playa	12.82
San Simon	7.69
White Water Draw	10.26

December 2009 - November 2012 (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	39.47	CD1	67.54
Upper Colorado	39.47	CD2	78.07
Little Colorado	28.95	CD3	83.77
Verde	15.79	CD4	85.96
Bill Williams	13.16	CD5	86.84
Agua Fria	13.16	CD6	98.25
Lower Gila	34.21	CD7	98.25
Salt	23.68
Lower Colorado	26.32
Upper Gila	7.89
Santa Cruz	2.63
San Pedro	10.53
Willcox Playa	10.53
San Simon	2.63
White Water Draw	5.26

December 2008- November 2012 (48-month): percentiles of precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

December 2012 Arizona Drought Update (based on precipitation data through November 2012)

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 precipitation was sparse statewide. Only one storm system passed through the state, on the 9^th through the 11^th. The storm even dropped a little snow on Payson, Show Low and Flagstaff, but precipitation totals were well below average, especially in the southeastern watersheds. Temperatures were much warmer than normal statewide, with the hottest conditions in Mohave, Pinal and Maricopa counties, all above the 97^th percentile.

The 3-month period was by far the driest short term period, with eight watersheds below the 20^th percentile and three below the 8^th percentile. During this interval the southern counties fared much better. As is often the case, the driest areas had the warmest temperatures, with all counties except those on the Colorado Plateau above the 89^th percentile.

The 6-month precipitation, essentially summer and fall, was near average in all areas of the state, with only Willcox Playa and White Water Draw drier than average, both below the 18^th percentile. The lower Gila and lower Colorado watersheds received above average precipitation, though much of that was received from very few storms. Six month temperatures were very high with fourteen counties above the 86^th percentile, while Mohave County enjoyed slightly cooler weather, only up to the 80^th percentile.

The 12-month period was much drier than average across all watersheds except the southwestern third of Arizona. Six watersheds were above the 20^th percentile, but nine were below. The twelve month period was very warm, with a gradient from southeast to northwest, with Mohave County the relative cool county.

The 24-month period continues to be the driest interval, covering two consecutive La Niña winters and two drier than average monsoons. Four watersheds are at the 25^th percentile while eight are below the 18^th percentile. The 24-month temperatures were very warm with the southern half of the state above the 88^th percentile, and only Mohave County below the 81^st percentile.

The 36-month period continues to be the wettest long term interval, as the two previous dry years are joined by the very wet El Niño winter of 2009-2010. but only the Virgin and Upper Colorado watersheds received greater than normal precipitation. Nine watersheds were below the 30^th percentile, and one was below the 8^th percentile. This reflects the wet El Niño winter of 2010. Eight watersheds were above the 33^rd percentile. Temperatures for the three year period were the coolest of the long term intervals, corresponding to the increased precipitation and winter storms. The northern counties were below the 82^nd percentile, while the warmest counties in southern Arizona were above the 86^h percentile.

The 48-month period was again much drier than normal as three dry years are not balanced with only one wet year. The southeastern watersheds fared the worst, but even central Arizona was dry as the Bill Williams, Agua Fria and Verde watersheds were all below the 16^th percentile. In the south, four watersheds were below the 8^th percentile, and two more were below the 11^th. Temperatures in the south central and southeastern counties were above the 98^th percentile, while Yuma, La Paz, and Gila counties were just above the 85^th percentile. The northern counties were all below the 75^th percentile.