State Precipitation & Temperature Update for Arizona

Conditions through February 2008

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 03/26/2008. The Upper Colorado and Santa Cruz still have some missing data. The data are preliminary.

Precipitation Percentiles by Watershed (through February 2008)

Temperature Percentiles by Climate Division (through February 2008)

SHORT TERM CONDITIONS: 1-6 MONTHS

February precipitation was near average for the southern half of the state, with slightly below-average precipitation in the southeast (Whitewater Draw and Willcox) and southwest (lower Colorado). The northern half of the state received well above-average precipitation for the month. The regular cycle of storms brought seasonable temperatures to the state, with all climate divisions reporting temperatures between the 45^th and 58^th percentiles. The three-month winter period of December through February has been very wet across most of the state, averaging between the 81^st and 95^th percentile. Cold, winter storms have moved through the state from the southwest to the northeast, throughout the winter. The driest watersheds are in the southeast, but they are between the 61^st and 73^rd percentile for precipitation, certainly wetter than average. The relatively cold weather in January and seasonal temperatures of February dropped the 3-month temperatures to near or below average. The 6-month period precipitation, from September through February, continues to remain near- or slightly below-average in the southeast, with Willcox and Whitewater Draw around the 35^th percentile. The colder than average winter temperatures in the north have brought the three northern climate divisions below the 67^th percentile, while the southeast remains above the 85^th percentile for temperature.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	57.89	CD1	46.49
Upper Colorado	81.58	CD2	51.75
Little Colorado	78.95	CD3	45.61
Verde	65.79	CD4	50.44
Bill Williams	50.00	CD5	54.82
Agua Fria	57.89	CD6	55.26
Lower Gila	42.11	CD7	57.89
Salt	60.53
Lower Colorado	39.47
Upper Gila	42.11
Santa Cruz	52.63
San Pedro	42.11
Willcox Playa	29.73
San Simon	47.37
White Water Draw	31.58

FEBRUARY 2008: 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	83.33	CD1	41.67
Upper Colorado	91.89	CD2	29.82
Little Colorado	94.44	CD3	29.39
Verde	91.67	CD4	51.75
Bill Williams	81.08	CD5	41.23
Agua Fria	81.08	CD6	32.46
Lower Gila	81.08	CD7	39.47
Salt	89.19
Lower Colorado	72.97
Upper Gila	72.97
Santa Cruz	72.97
San Pedro	62.86
Willcox Playa	63.89
San Simon	81.08
White Water Draw	61.11

DECEMBER 2008 - FEBRUARY 2008 (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	44.12	CD1	66.67
Upper Colorado	83.78	CD2	63.16
Little Colorado	63.89	CD3	63.16
Verde	69.44	CD4	86.84
Bill Williams	56.76	CD5	70.18
Agua Fria	56.76	CD6	83.33
Lower Gila	67.57	CD7	87.72
Salt	81.08
Lower Colorado	45.95
Upper Gila	56.76
Santa Cruz	54.05
San Pedro	45.71
Willcox Playa	36.11
San Simon	72.97
White Water Draw	33.33

SEPTEMBER 2008 – FEBRUARY 2008 (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 again improved across all watersheds except the Upper Gila. Only the Virgin watershed is below average, below the 9^th percentile. Temperatures remained high for all climate divisions, except the northwest, which finally dropped below the 85^th percentile.

The 24-month period has seven watersheds below average, five watersheds near average, and three watersheds above average for precipitation. The drier watersheds are in the west and south central region, while the wetter than average watersheds are in the southeast. This is the opposite of the shorter-term precipitation conditions, which have the southeast as the driest region. The 24-month period picks up the past two monsoons which were very wet in the southeast. Temperatures for the 24-month period continue to be above the 86^th percentile everywhere but the northwest, where they dropped just below the 79^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	8.57	CD1	80.53
Upper Colorado	81.08	CD2	92.04
Little Colorado	70.27	CD3	92.04
Verde	62.16	CD4	93.81
Bill Williams	51.35	CD5	92.92
Agua Fria	51.35	CD6	97.35
Lower Gila	83.78	CD7	98.23
Salt	70.27
Lower Colorado	62.16
Upper Gila	59.46
Santa Cruz	48.65
San Pedro	43.24
Willcox Playa	41.67
San Simon	67.57
White Water Draw	44.44

MARCH 2008 – FEBRUARY 2008 (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	20.59	CD1	78.57
Upper Colorado	61.11	CD2	86.61
Little Colorado	63.89	CD3	88.39
Verde	47.22	CD4	86.61
Bill Williams	16.67	CD5	90.18
Agua Fria	31.94	CD6	93.75
Lower Gila	66.67	CD7	97.32
Salt	58.33
Lower Colorado	36.11
Upper Gila	63.89
Santa Cruz	41.67
San Pedro	50.00
Willcox Playa	61.11
San Simon	41.67
White Water Draw	63.89

MARCH 2007 – FEBRUARY 2008 (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 again the driest period with all watersheds below the 38^th percentile. Five watersheds are below the 15^th percentile and eight are between the 25^th and 38^th percentiles. Bill Williams and Agua Fria in west central Arizona, the San Simon, Santa Cruz, and San Pedro in the south remain extremely dry in the long-term, and the upper Gila has now fallen below the 15^th percentile. Temperatures over the three-year period are above the 87^th percentile in all climate divisions except the northwest, which he fallen below the 75^th percentile.

The 48-month period is still split with above-average precipitation in the western watersheds, below-average precipitation in the southeastern watersheds, and near- average precipitation in the central and eastern watersheds. Santa Cruz, San Pedro and San Simon continue to be the driest long-term watersheds, while the upper and lower Colorado are the wisest watersheds. Climate division 7 in the southeast has had the hottest 4-year period since 1895, and only the northwest climate division of Mohave County remains below the 90^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	27.27	CD1	74.77
Upper Colorado	34.29	CD2	87.84
Little Colorado	37.14	CD3	90.99
Verde	17.14	CD4	94.59
Bill Williams	5.71	CD5	87.39
Agua Fria	5.71	CD6	95.50
Lower Gila	31.43	CD7	99.10
Salt	25.71
Lower Colorado	34.29
Upper Gila	14.29
Santa Cruz	11.43
San Pedro	20.00
Willcox Playa	31.43
San Simon	5.71
White Water Draw	34.29

MARCH 2006 – FEBRUARY 2008 (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	58.06	CD1	76.36
Upper Colorado	76.47	CD2	90.00
Little Colorado	44.12	CD3	92.73
Verde	58.82	CD4	95.45
Bill Williams	50.00	CD5	90.00
Agua Fria	52.94	CD6	94.55
Lower Gila	64.71	CD7	100.00
Salt	55.88
Lower Colorado	79.41
Upper Gila	44.12
Santa Cruz	11.76
San Pedro	23.53
Willcox Playa	44.12
San Simon	29.41
White Water Draw	50.00

MARCH 2005 – FEBRUARY 2008 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

March 2008 Arizona Drought Update based on precipitation data through February 2008)

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 winter period of December through February has been very wet across most of the state, averaging between the 81^st and 95^th percentile. Cold, winter storms have moved through the state from the southwest to the northeast, throughout the winter. The driest watersheds are in the southeast, but they are between the 61^st and 73^rd percentile for precipitation, certainly wetter than average. The relatively cold weather in January and seasonal temperatures of February dropped the 3-month temperatures to near or below average.

The 6-month period precipitation, from September through February, continues to remain near- or slightly below-average in the southeast, with Willcox and Whitewater Draw around the 35^th percentile. The colder than average winter temperatures in the north have brought the three northern climate divisions below the 67^th percentile, while the southeast remains above the 85^th percentile for temperature.