State Precipitation & Temperature Update for Arizona

Conditions through January 2007

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 2/26/2007. The data are preliminary, and there are some missing precipitation data in the San Pedro watershed.

Precipitation Percentiles by Watershed (through January 2007)

Temperature Percentiles by Climate Division (through January 2007)

SHORT TERM CONDITIONS: 1-6 MONTHS

January precipitation was below average in the northern and western watersheds and near average over most of the state. The Willcox and White Water Draw watersheds had above average precipitation as the January storm tracks came across Mexico and moved northward into New Mexico. Temperatures were near average in the northwest and below average across the eastern and southern portions of the state, with Maricopa and Pinal counties and the Lower Colorado River below the 36^th percentile for temperature. The 3-month period of November through January was much drier than average, below the 25^th percentile everywhere, except the southeast corner, where the southerly storm tracks in January dropped precipitation on their way into New Mexico. Temperatures over the 3-month period were slightly above average for most of the state, due in part to the extremely warm November. The coolest temperatures were in Maricopa and Pinal counties, which had very cold temperatures in both December and January. The 6-month period, August through January, which represents a fairly dry fall and early winter season is below average for the most of the state, and near average for the southeast and Colorado River watersheds. Only White Water Draw remains well above average at the 62^nd percentile. Temperatures were near or slightly above average everywhere in the state for the past six months ranging from the 40^th to the 65^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	34.72	CD1	46.02
Upper Colorado	37.84	CD2	35.40
Little Colorado	50.00	CD3	42.92
Verde	43.24	CD4	28.76
Bill Williams	29.73	CD5	20.35
Agua Fria	45.95	CD6	24.78
Lower Gila	40.54	CD7	29.20
Salt	51.35
Lower Colorado	35.14
Upper Gila	56.76
Santa Cruz	40.54
San Pedro	48.65
Willcox Playa	64.86
San Simon	48.65
White Water Draw	86.11

JANUARY 2007: 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	23.53	CD1	65.49
Upper Colorado	16.67	CD2	70.35
Little Colorado	17.14	CD3	68.58
Verde	14.29	CD4	61.95
Bill Williams	8.33	CD5	44.25
Agua Fria	16.67	CD6	55.31
Lower Gila	11.11	CD7	64.60
Salt	16.67
Lower Colorado	13.89
Upper Gila	25.00
Santa Cruz	8.33
San Pedro	32.35
Willcox Playa	40.00
San Simon	13.89
White Water Draw	45.71

NOVEMBER 2006 - JANUARY 2007 (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	24.24	CD1	65.49
Upper Colorado	41.67	CD2	43.36
Little Colorado	31.43	CD3	55.75
Verde	31.43	CD4	40.27
Bill Williams	13.89	CD5	57.96
Agua Fria	36.11	CD6	63.72
Lower Gila	33.33	CD7	46.02
Salt	33.33
Lower Colorado	41.67
Upper Gila	44.44
Santa Cruz	33.33
San Pedro	47.06
Willcox Playa	57.14
San Simon	25.00
White Water Draw	62.86

AUGUST 2006 – JANUARY 2007 (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

Precipitation for the 12-month period is still well below average across most of the state, except for the southeast watersheds which benefited from an extremely wet monsoon, and from the southern storm tracks in January. The southeast and south central climate divisions are still the hottest, but all divisions are below the 95^th percentile.

The two-year period shows only the Lower Colorado, Virgin River and White Water Draw watersheds are above the 42nd percentile for precipitation. The rest of the state is below the 38^th percentile, as the 24 month period no longer includes the wet December 2004 or January 2005. Last month only 2 watersheds were below the 25^th percentile, and now 7 of the 15 watersheds are below the 25^th percentile. This demonstrates just how inconsistent our winter precipitation can be. For temperature, only the northwest climate division is below the 75^th percentile. The southeast climate division remains the hot spot at the 99^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	35.29	CD1	75.00
Upper Colorado	22.22	CD2	75.89
Little Colorado	36.11	CD3	83.93
Verde	22.22	CD4	78.57
Bill Williams	5.56	CD5	81.70
Agua Fria	13.89	CD6	86.61
Lower Gila	22.22	CD7	94.64
Salt	27.78
Lower Colorado	19.44
Upper Gila	50.00
Santa Cruz	41.67
San Pedro	63.89
Willcox Playa	66.67
San Simon	16.67
White Water Draw	60.00

FEBRUARY 2006 – JANUARY 2007 (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	60.61	CD1	72.97
Upper Colorado	34.29	CD2	88.29
Little Colorado	20.00	CD3	86.49
Verde	20.00	CD4	89.19
Bill Williams	11.43	CD5	84.68
Agua Fria	20.00	CD6	90.99
Lower Gila	28.57	CD7	99.10
Salt	20.00
Lower Colorado	54.29
Upper Gila	28.57
Santa Cruz	11.43
San Pedro	31.43
Willcox Playa	37.14
San Simon	5.71
White Water Draw	42.86

FEBRUARY 2005 – JANUARY 2007 (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 precipitation remains well above average in the northern and western watersheds, below average in the south central watersheds and near average elsewhere in the state. The Santa Cruz and San Simon watersheds continue to be the driest. Gila County and the southeast climate division remain above the 95^th percentile for temperature, and the coolest area is still the northwest in the 74^th percentile.

The dry El Niño has produced very little change in the 48-month precipitation patterns. The state is still split with the eastern half drier than average and the western half wetter than average. The central watersheds remain near normal. Temperatures are above the 75^th percentile everywhere in the state, with the hot spots in Gila County and the southeast climate division above the 96^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	93.75	CD1	74.55
Upper Colorado	70.59	CD2	90.91
Little Colorado	44.12	CD3	86.36
Verde	55.88	CD4	95.45
Bill Williams	50.00	CD5	87.27
Agua Fria	50.00	CD6	90.91
Lower Gila	61.76	CD7	98.18
Salt	38.24
Lower Colorado	82.35
Upper Gila	41.18
Santa Cruz	8.82
San Pedro	41.18
Willcox Playa	47.06
San Simon	11.76
White Water Draw	50.00

FEBRUARY 2004 – JANUARY 2007 (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	-99.99	CD1	77.06
Upper Colorado	63.64	CD2	91.74
Little Colorado	18.18	CD3	91.74
Verde	54.55	CD4	96.33
Bill Williams	48.48	CD5	88.07
Agua Fria	51.52	CD6	90.83
Lower Gila	60.61	CD7	98.17
Salt	42.42
Lower Colorado	74.24
Upper Gila	27.27
Santa Cruz	12.12
San Pedro	21.21
Willcox Playa	18.18
San Simon	21.21
White Water Draw	36.36

FEBRUARY 2003 – JANUARY 2007 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

February 2007 Arizona Drought Update based on Precipitation (data through January 2007)

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

SUMMARY

January - Precipitation was below average in the northern and western watersheds and near average over most of the state. The Willcox and White Water Draw watersheds had above average precipitation as the January storm tracks came across Mexico and moved northward into New Mexico. Temperatures were near average in the northwest and below average across the eastern and southern portions of the state, with Maricopa and Pinal counties and the Lower Colorado River below the 36^th percentile for temperature.

Three-month period – November through January was much drier than average, below the 25^th percentile everywhere, except the southeast corner, where the southerly storm tracks in January dropped precipitation on their way into New Mexico. Temperatures over the 3-month period were slightly above average for most of the state, due in part to the extremely warm November. The coolest temperatures were in Maricopa and Pinal counties, which had very cold temperatures in both December and January.

Six-month period – August through January, which represents a fairly dry fall and early winter season, is below average for the most of the state, and near average for the southeast and Colorado River watersheds. Only White Water Draw remains well above average at the 62^nd percentile. Temperatures were near or slightly above average everywhere in the state for the past six months ranging from the 40^th to the 65^th percentile.

Twelve-month period – Precipitation for the 12-month period is still well below average across most of the state, except for the southeast watersheds which benefited from an extremely wet monsoon, and from the southern storm tracks in January. The southeast and south central climate divisions are still the hottest, but all divisions are below the 95^th percentile.

Two-year period - Only the Lower Colorado, Virgin River and White Water Draw watersheds are above the 42nd percentile for precipitation. The rest of the state is below the 38^th percentile, as the 24 month period no longer includes the wet December 2004 or January 2005. Last month only 2 watersheds were below the 25^th percentile, and now 7 of the 15 watersheds are below the 25^th percentile. This demonstrates just how inconsistent our winter precipitation can be. For temperature, only the northwest climate division is below the 75^th percentile. The southeast climate division remains the hot spot at the 99^th percentile.

Three-year period - Precipitation remains well above average in the northern and western watersheds, below average in the south central watersheds and near average elsewhere in the state. The Santa Cruz and San Simon watersheds continue to be the driest. Gila County and the southeast climate division remain above the 95^th percentile for temperature, and the coolest area is still the northwest in the 74^th percentile.

Four-year period - The dry El Niño has produced very little change in the 48-month precipitation patterns. The state is still split with the eastern half drier than average and the western half wetter than average. The central watersheds remain near normal. Temperatures are above the 75^th percentile everywhere in the state, with the hot spots in Gila County and the southeast climate division above the 96^th percentile.