State Precipitation & Temperature Update for Arizona

Conditions through January 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 02/20/2008. The data are preliminary.

Precipitation Percentiles by Watershed (through January 2008)

Temperature Percentiles by Climate Division (through January 2008)

SHORT TERM CONDITIONS: 1-6 MONTHS

Like December, January was extremely wet most places in the state, above the 78^th percentile. The exceptions were in the northwest and southeast, where precipitation was near average. January temperatures were near average along the lower Colorado River and in the southern climate divisions, and well below average in central and northeastern Arizona where cold winter storms brought significant snowfall to the state. The three-month period of November through January has been extremely wet across most of the state, averaging between the 63^rd and 95^th percentile. All three months have had strong winter storms that tapped into subtropical moisture. Although all climate divisions of the state had above-average 3-month temperatures, much of the precipitation has fallen as snow, and the snow pack remains well above average. For the second month in a row, the 3-month temperatures have dropped across the state. The 6-month period precipitation was again near- to slightly below-average in the southeast, and well above average in all other watersheds. This period reflects the tail end of the wet monsoon along with the wet winter. The dry spot in the state is the Virgin watershed, which is just below the 15^th percentile. The Virgin watershed received almost no monsoon precipitation, and has only received winter precipitation from a few of the storms, particularly the December events. The colder than average winter temperatures have brought all but two climate divisions down below the 85^th percentile. Last month all 7 divisions were above the 85^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	56.76	CD1	49.12
Upper Colorado	97.37	CD2	28.95
Little Colorado	83.78	CD3	32.89
Verde	84.21	CD4	61.40
Bill Williams	89.47	CD5	54.82
Agua Fria	84.21	CD6	53.07
Lower Gila	86.84	CD7	53.07
Salt	89.47
Lower Colorado	84.21
Upper Gila	78.95
Santa Cruz	57.89
San Pedro	47.37
Willcox Playa	39.47
San Simon	86.84
White Water Draw	40.54

JANUARY 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	68.57	CD1	75.88
Upper Colorado	91.89	CD2	62.28
Little Colorado	86.11	CD3	62.28
Verde	86.11	CD4	83.33
Bill Williams	86.49	CD5	77.19
Agua Fria	86.49	CD6	78.95
Lower Gila	91.89	CD7	71.93
Salt	94.59
Lower Colorado	75.68
Upper Gila	81.08
Santa Cruz	83.78
San Pedro	71.43
Willcox Playa	63.89
San Simon	89.19
White Water Draw	63.89

NOVEMBER 2008 - JANUARY 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	14.71	CD1	76.32
Upper Colorado	83.78	CD2	77.19
Little Colorado	72.22	CD3	80.70
Verde	80.56	CD4	90.35
Bill Williams	64.86	CD5	84.21
Agua Fria	64.86	CD6	91.23
Lower Gila	75.68	CD7	84.21
Salt	81.08
Lower Colorado	48.65
Upper Gila	62.16
Santa Cruz	45.95
San Pedro	48.57
Willcox Playa	47.22
San Simon	62.16
White Water Draw	47.22

AUGUST 2008 – JANUARY 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 improved across almost every watershed with 8 watersheds well above average, 5 near average and only 2 below average. The 12-month period became warmer for most climate divisions with all climbing above the 86^th percentile.

The 24 month period is no longer the driest long-term period. Three watersheds in the southeast are well above average, five are now near average, four are slightly below average and three remain well below average. The driest are in northwest and west central Arizona. Temperatures for the 24-month period have dropped below the 80^th percentile in the northwest, and remain above the 96^th percentile in the south.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	5.71	CD1	86.73
Upper Colorado	75.68	CD2	94.69
Little Colorado	72.97	CD3	92.04
Verde	62.16	CD4	92.92
Bill Williams	43.24	CD5	93.81
Agua Fria	51.35	CD6	98.23
Lower Gila	81.08	CD7	96.46
Salt	78.38
Lower Colorado	59.46
Upper Gila	62.16
Santa Cruz	37.84
San Pedro	40.54
Willcox Playa	40.54
San Simon	62.16
White Water Draw	41.67

FEBRUARY 2008 – JANUARY 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	17.65	CD1	79.46
Upper Colorado	44.44	CD2	88.39
Little Colorado	52.78	CD3	90.18
Verde	36.11	CD4	90.18
Bill Williams	19.44	CD5	91.07
Agua Fria	25.00	CD6	92.86
Lower Gila	52.78	CD7	96.43
Salt	52.78
Lower Colorado	38.89
Upper Gila	61.11
Santa Cruz	33.33
San Pedro	50.00
Willcox Playa	66.67
San Simon	30.56
White Water Draw	63.89

FEBRUARY 2007 – JANUARY 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 has become the driest period with 14 watersheds below the 50^th percentile, 10 below the 37^th percentile, and 5 below the 22^nd percentile. The driest are the Bill Williams and Agua Fria in west central Arizona and the San Simon, Santa Cruz, and San Pedro in the south. Temperatures over the three-year period remain high with all but the northwest climate division above the 89^th percentile.

The 48-month period continues to show above average precipitation across the western and northern watersheds, near average precipitation in the central and eastern watersheds, and below average precipitation in the southern watersheds. Both the San Simon and Santa Cruz watersheds are below the 15^th percentile. Two climate divisions in southern and central Arizona are above the 95^th percentile for temperature, and 4 others are between the 88^th and 94^th percentiles. Only the northwest climate division of Mohave County is below the 77^th percentile.

Watershed	Precipitation Percentile	Climate Division	Temperature Percentile
Virgin	33.33	CD1	75.68
Upper Colorado	42.86	CD2	90.99
Little Colorado	45.71	CD3	91.89
Verde	28.57	CD4	93.69
Bill Williams	11.43	CD5	89.19
Agua Fria	17.14	CD6	93.69
Lower Gila	54.29	CD7	99.10
Salt	37.14
Lower Colorado	48.57
Upper Gila	37.14
Santa Cruz	14.29
San Pedro	22.86
Willcox Playa	37.14
San Simon	11.43
White Water Draw	48.57

FEBRUARY 2006 – JANUARY 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	67.74	CD1	76.36
Upper Colorado	76.47	CD2	91.82
Little Colorado	47.06	CD3	88.18
Verde	55.88	CD4	95.45
Bill Williams	50.00	CD5	88.18
Agua Fria	52.94	CD6	93.64
Lower Gila	64.71	CD7	99.09
Salt	55.88
Lower Colorado	82.35
Upper Gila	47.06
Santa Cruz	8.82
San Pedro	32.35
Willcox Playa	50.00
San Simon	14.71
White Water Draw	52.94

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

February 2008 Arizona Drought Update based on precipitation data through January 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 period of November through January has been extremely wet across most of the state, averaging between the 63^rd and 95^th percentile. All three months have had strong winter storms that tapped into subtropical moisture. Although all climate divisions of the state had above-average 3-month temperatures, much of the precipitation has fallen as snow, and the snow pack remains well above average. For the second month in a row, the 3-month temperatures have dropped across the state.

The 6-month period precipitation was again near- to slightly below-average in the southeast, and well above average in all other watersheds. This period reflects the tail end of the wet monsoon along with the wet winter. The dry spot in the state is the Virgin watershed, which is just below the 15^th percentile. The Virgin watershed received almost no monsoon precipitation, and has only received winter precipitation from a few of the storms, particularly the December events. The colder than average winter temperatures have brought all but two climate divisions down below the 85^th percentile. Last month all 7 divisions were above the 85^th percentile.