State Precipitation & Temperature Update for Arizona

Conditions through May 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 6/25/2012. The data are preliminary.

Precipitation Percentiles by Watershed (through May 2012)

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Temperature Percentiles by Climate Division (through May 2012)

SHORT TERM CONDITIONS: 1-6 MONTHS

May was a mixed month for precipitation. The lower Gila, Sam Simon, White Water Draw and Santa Cruz watersheds were wetter than average, while the Virgin, Agua Fria and Little Colorado watersheds were much drier than average, below the 8^th percentile. Four watersheds are near average and three others are slightly drier than average. All counties were much warmer than average, with only Coconino, Navajo and Apache Counties below the 87^th percentile. The three month period is one of the driest short-term intervals with 10 watersheds below the 29^th percentile, and five near average. Three month temperatures were much warmer than average statewide with only Gila County below the 87^th percentile. Six month precipitation was the wettest with seven watersheds near average and seven drier than average. Only one watershed, the Virgin, was below the 17^th percentile. The six month period does include the very wet month of December. Six month temperatures were slightly warmer than normal across the state, except the southern counties which were all above the 87^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	5.95	CD1	90.68
Upper Colorado	23.81	CD2	84.32
Little Colorado	4.76	CD3	90.68
Verde	11.90	CD4	87.29
Bill Williams	11.90	CD5	93.22
Agua Fria	7.14	CD6	91.53
Lower Gila	73.81	CD7	91.53
Salt	30.95
Lower Colorado	23.81
Upper Gila	47.62
Santa Cruz	66.67
San Pedro	47.62
Willcox Playa	52.38
San Simon	78.57
White Water Draw	69.05

May 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	5.95	CD1	88.03
Upper Colorado	16.67	CD2	88.14
Little Colorado	16.67	CD3	88.98
Verde	33.33	CD4	62.29
Bill Williams	47.62	CD5	87.29
Agua Fria	47.62	CD6	89.83
Lower Gila	26.19	CD7	92.37
Salt	21.43
Lower Colorado	30.95
Upper Gila	16.67
Santa Cruz	21.43
San Pedro	14.29
Willcox Playa	28.57
San Simon	47.62
White Water Draw	33.33

March 2012 - May 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	5.00	CD1	81.36
Upper Colorado	17.07	CD2	78.81
Little Colorado	32.50	CD3	79.66
Verde	22.50	CD4	60.59
Bill Williams	39.02	CD5	83.05
Agua Fria	39.02	CD6	87.29
Lower Gila	24.39	CD7	89.83
Salt	24.39
Lower Colorado	19.51
Upper Gila	34.15
Santa Cruz	29.27
San Pedro	25.64
Willcox Playa	35.00
San Simon	36.59
White Water Draw	40.00

December 2011 – May 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 is the other driest short term interval, with three watersheds near average, and the other 12 all drier than average, with eight of those below the 20^th percentile. Temperatures were much warmer than average, with only the northern counties below the 75^th percentile.

The 24-month period is the driest long-term interval with all but two watersheds, the upper and Little Colorado, below the 20^th percentile. Three watersheds the upper Gila, Santa Cruz and San Simon are at or below the 5^th percentile. The 24 month interval is the warmest long term period. Temperatures for the last 2 years have been much warmer than average in the southern and southeastern counties, but only slightly warmer than average in Mohave County.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	12.82	CD1	75.21
Upper Colorado	29.27	CD2	80.34
Little Colorado	34.15	CD3	86.32
Verde	14.63	CD4	85.47
Bill Williams	19.51	CD5	88.03
Agua Fria	17.07	CD6	89.74
Lower Gila	24.39	CD7	94.02
Salt	17.07
Lower Colorado	17.07
Upper Gila	21.95
Santa Cruz	14.63
San Pedro	31.71
Willcox Playa	27.50
San Simon	14.63
White Water Draw	35.00

June 2011 - May 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	13.16	CD1	69.83
Upper Colorado	37.50	CD2	77.59
Little Colorado	42.50	CD3	84.48
Verde	20.00	CD4	86.21
Bill Williams	10.00	CD5	86.21
Agua Fria	7.50	CD6	93.10
Lower Gila	15.00	CD7	97.41
Salt	17.50
Lower Colorado	17.50
Upper Gila	5.00
Santa Cruz	2.50
San Pedro	7.50
Willcox Playa	12.50
San Simon	2.50
White Water Draw	15.00

June 2010 – May 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 has three watersheds with near average precipitation and three watersheds slightly drier than average. Nine watersheds are below the 18^th percentile and two of those, the Santa Cruz and San Simon, are below the 3^rd percentile. Temperatures for the three year period were below the 66^th percentile across the northern counties, and above the 91^st percentile in the southern counties.

The 48-month period also has three watersheds, the upper Colorado, lower Gila, and Salt, near average and four watersheds slightly drier than normal. Eight more are below the 16^th percentile, with the Santa Cruz and San Simon below the 3^rd percentile. The 48 month period has only Maricopa and Pinal counties above the 96^th percentile. Mohave County is below the 67^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	24.32	CD1	65.22
Upper Colorado	43.59	CD2	65.65
Little Colorado	33.33	CD3	78.26
Verde	17.95	CD4	79.13
Bill Williams	10.26	CD5	84.35
Agua Fria	7.69	CD6	91.30
Lower Gila	33.33	CD7	92.17
Salt	20.51
Lower Colorado	28.21
Upper Gila	7.69
Santa Cruz	2.56
San Pedro	12.82
Willcox Playa	12.82
San Simon	2.56
White Water Draw	10.26

June 2009 - May 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	14.29	CD1	66.67
Upper Colorado	44.74	CD2	78.95
Little Colorado	28.95	CD3	81.58
Verde	21.05	CD4	76.75
Bill Williams	10.53	CD5	83.33
Agua Fria	5.26	CD6	99.12
Lower Gila	50.00	CD7	93.86
Salt	36.84
Lower Colorado	21.05
Upper Gila	21.05
Santa Cruz	2.63
San Pedro	13.16
Willcox Playa	10.53
San Simon	2.63
White Water Draw	15.79

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

June 2012 Arizona Drought Update (based on precipitation data through May 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

May was a mixed month for precipitation. The lower Gila, Sam Simon, White Water Draw and Santa Cruz watersheds were wetter than average, while the Virgin, Agua Fria and Little Colorado watersheds were much drier than average, below the 8^th percentile. Four watersheds are near average and three others are slightly drier than average. All counties were much warmer than average, with only Coconino, Navajo and Apache Counties below the 87^th percentile.

The 3-month period is one of the driest short-term intervals with 10 watersheds below the 29^th percentile, and five near average. Three month temperatures were much warmer than average statewide with only Gila County below the 87^th percentile.

The 6-month period does include the very wet month of December. Six month temperatures were slightly warmer than normal across the state, except the southern counties which were all above the 87^th percentile.

The 12-month period is the other driest short term interval, with three watersheds near average, and the other 12 all drier than average, with eight of those below the 20^th percentile. Temperatures were much warmer than average, with only the northern counties below the 75^th percentile.

The 24-month period is the driest long-term interval with all but two watersheds, the upper and Little Colorado, below the 20^th percentile. Three watersheds the upper Gila, Santa Cruz and San Simon are at or below the 5^th percentile. The 24 month interval is the warmest long term period. Temperatures for the last 2 years have been much warmer than average in the southern and southeastern counties, but only slightly warmer than average in Mohave County.

The 36-month period has three watersheds with near average precipitation and three watersheds slightly drier than average. Nine watersheds are below the 18^th percentile and two of those, the Santa Cruz and San Simon, are below the 3^rd percentile. Temperatures for the three year period were below the 66^th percentile across the northern counties, and above the 91^st percentile in the southern counties.

The 48-month period also has three watersheds, the upper Colorado, lower Gila, and Salt, near average and four watersheds slightly drier than normal. Eight more are below the 16^th percentile, with the Santa Cruz and San Simon below the 3^rd percentile. The 48 month period has only Maricopa and Pinal counties above the 96^th percentile. Mohave County is below the 67^th percentile.