State Precipitation & Temperature Update for Arizona

Conditions through June 2009

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. Current update is 07/25/2009. The data are preliminary.

Precipitation Percentiles by Watershed (through June 2009)

Temperature Percentiles by Climate Division (through June 2009)

SHORT TERM CONDITIONS: 1-6 MONTHS

June precipitation was well above average in the eastern third of the state and slightly above average in northern Arizona. The western and southern watersheds had near-average or slightly below average precipitation. Temperatures along the lower Colorado River were near average, while the rest of the state had cooler than average temperatures in June. The three-month period of April through June was wetter than average across most of Arizona, with the Bill Williams and Lower Colorado watersheds slightly drier than average, and the Santa Cruz watershed near average. The wet conditions were due to an unusually wet May and late June, as April was very dry in the southwest. Temperatures for the three-month period were only slightly warmer than average due to the large number of cloudy days statewide. The six-month period precipitation was below average in all watersheds except the San Pedro, Willcox Playa, and Whitewater Draw in the southeast. These three watersheds have received almost all of their moisture during the past two months. The rest of the state is below average because the normally wet months of March and April were almost completely dry statewide. Temperatures over the last six months were above average in all climate divisions, with only Gila County below the 73^rd percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	50.00	CD1	50.43
Upper Colorado	71.79	CD2	20.87
Little Colorado	87.18	CD3	35.22
Verde	61.54	CD4	27.83
Bill Williams	56.41	CD5	43.48
Agua Fria	41.03	CD6	60.87
Lower Gila	46.15	CD7	35.65
Salt	87.18
Lower Colorado	30.77
Upper Gila	92.31
Santa Cruz	25.64
San Pedro	94.87
Willcox Playa	94.87
San Simon	61.54
White Water Draw	87.18

JUNE 2009: 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	21.05	CD1	76.32
Upper Colorado	74.36	CD2	65.22
Little Colorado	82.05	CD3	61.74
Verde	64.10	CD4	72.61
Bill Williams	35.90	CD5	73.48
Agua Fria	76.92	CD6	83.48
Lower Gila	71.79	CD7	72.17
Salt	76.92
Lower Colorado	38.46
Upper Gila	82.05
Santa Cruz	51.28
San Pedro	87.18
Willcox Playa	89.74
San Simon	84.62
White Water Draw	82.05

APRIL 2008 - JUNE 2009 (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	8.11	CD1	78.07
Upper Colorado	28.21	CD2	77.39
Little Colorado	36.84	CD3	77.83
Verde	25.64	CD4	72.17
Bill Williams	17.95	CD5	75.65
Agua Fria	20.51	CD6	93.91
Lower Gila	15.38	CD7	92.17
Salt	35.90
Lower Colorado	23.08
Upper Gila	30.77
Santa Cruz	17.95
San Pedro	41.03
Willcox Playa	57.89
San Simon	23.08
White Water Draw	50.00

JANUARY 2008 – JUNE 2009 (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 precipitation was near or slightly below average in the northern half of the state and somewhat mixed in southern Arizona. Four watersheds in southern Arizona had near average precipitation, four had above average precipitation, and one had below average precipitation. During the past 12 months, all areas of the state have had above average temperatures, with all counties except Gila County above the 77^th percentile.

The 24 month period is the wettest long-term period with only three watersheds having below average precipitation. Four watersheds received above average precipitation and eight had near average precipitation. Temperatures were well above average statewide, with the southern half of the state above the 86^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	5.56	CD1	77.19
Upper Colorado	52.63	CD2	82.46
Little Colorado	34.21	CD3	83.33
Verde	36.84	CD4	63.16
Bill Williams	36.84	CD5	89.47
Agua Fria	36.84	CD6	97.37
Lower Gila	68.42	CD7	79.82
Salt	68.42
Lower Colorado	52.63
Upper Gila	60.53
Santa Cruz	26.32
San Pedro	60.53
Willcox Playa	48.65
San Simon	55.26
White Water Draw	51.35

JULY 2008 – JUNE 2009 (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	2.86	CD1	71.68
Upper Colorado	67.57	CD2	84.07
Little Colorado	59.46	CD3	84.96
Verde	45.95	CD4	75.22
Bill Williams	40.54	CD5	90.27
Agua Fria	35.14	CD6	97.35
Lower Gila	78.38	CD7	86.73
Salt	72.97
Lower Colorado	55.41
Upper Gila	54.05
Santa Cruz	29.73
San Pedro	43.24
Willcox Playa	48.65
San Simon	67.57
White Water Draw	45.95

JULY 2007 – JUNE 2009 (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 precipitation is unevenly distributed with five watersheds in southern Arizona wetter than average, three drier than average and two near average. Northern Arizona was near average or drier than average for the previous three years. Temperatures over the three-year period remain well above average with only the northwest climate division below the 76^th percentile.

The 48-month period is still the driest long term period, with only one watershed near average, and 7 at or below the 20^th percentile. The four-year temperatures continue to be extremely high, with six climate divisions above the 90^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	2.94	CD1	75.00
Upper Colorado	47.22	CD2	84.82
Little Colorado	50.00	CD3	86.61
Verde	30.56	CD4	80.36
Bill Williams	16.67	CD5	87.95
Agua Fria	22.22	CD6	99.11
Lower Gila	66.67	CD7	87.05
Salt	63.89
Lower Colorado	38.89
Upper Gila	66.67
Santa Cruz	30.56
San Pedro	61.11
Willcox Playa	66.67
San Simon	38.89
White Water Draw	58.33

JULY 2006 – JUNE 2009 (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	3.03	CD1	75.89
Upper Colorado	20.00	CD2	90.99
Little Colorado	28.57	CD3	88.29
Verde	8.57	CD4	90.99
Bill Williams	2.86	CD5	90.99
Agua Fria	5.71	CD6	100.00
Lower Gila	45.71	CD7	99.10
Salt	37.14
Lower Colorado	25.71
Upper Gila	25.71
Santa Cruz	11.43
San Pedro	25.71
Willcox Playa	40.00
San Simon	14.29
White Water Draw	37.14

JULY 2005 – JUNE 2009 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

July 2009 Arizona Drought Update based on precipitation data through June 2009)

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

SUMMARY

The 3-month period of April through June was wetter than average across most of Arizona, with the Bill Williams and Lower Colorado watersheds slightly drier than average, and the Santa Cruz watershed near average. The wet conditions were due to an unusually wet May and late June, as April was very dry in the southwest. Temperatures for the three-month period were only slightly warmer than average due to the large number of cloudy days statewide.

The 6-month period precipitation was below average in all watersheds except the San Pedro, Willcox Playa, and Whitewater Draw in the southeast. These three watersheds have received almost all of their moisture during the past two months. The rest of the state is below average because the normally wet months of March and April were almost completely dry statewide. Temperatures over the last six months were above average in all climate divisions, with only Gila County below the 73^rd percentile.