State Precipitation & Temperature Update for Arizona

Conditions through February 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 100th 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 100th 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 03/29/2009. The data are preliminary.


Precipitation Percentiles by Watershed (through February 2009)

 

Temperature Percentiles by Climate Division (through February 2009)


SHORT TERM CONDITIONS: 1-6 MONTHS

February precipitation was near or slightly above average across northern and western Arizona, and slightly below average in the southeastern watersheds. Temperatures were near or slightly above average in the northern half of the state, and significantly warmer than average in the southern half. The three-month period of December through February was wetter than average for all but the southeastern third of the state. The two driest watersheds, Santa Cruz and Willcox Playa were below the 25th percentile. Temperatures for the three month period were near average in Gila County, slightly warmer than average along the western edge of the state, and well above average in the rest of the state. The six-month period precipitation was near average in the western half of the state, and in the Salt River basin. The Little Colorado River and the southeastern watersheds were drier than average, all below the 29th percentile. Five watersheds were below the 23rd percentile. Temperatures over the last six months were near average in Gila County, and well above average in all other counties. The warmest temperatures were in Yuma, Pinal and Maricopa counties, all above the 95th percentile.

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

25.64

CD1

64.78

Upper Colorado

41.03

CD2

68.70

Little Colorado

43.59

CD3

59.57

Verde

61.54

CD4

46.09

Bill Williams

66.67

CD5

50.00

Agua Fria

57.69

CD6

80.43

Lower Gila

56.41

CD7

81.74

Salt

76.92

 

Lower Colorado

74.36

 

Upper Gila

35.90

 

Santa Cruz

38.46

 

San Pedro

38.46

 

Willcox Playa

26.32

 

San Simon

56.41

 

White Water Draw

25.64

 

FEBRUARY 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

35.14

CD1

73.04

Upper Colorado

73.68

CD2

79.13

Little Colorado

70.27

CD3

63.48

Verde

59.46

CD4

57.39

Bill Williams

60.53

CD5

70.87

Agua Fria

57.89

CD6

88.70

Lower Gila

60.53

CD7

80.43

Salt

76.32

 

Lower Colorado

71.05

 

Upper Gila

47.37

 

Santa Cruz

39.47

 

San Pedro

36.11

 

Willcox Playa

21.62

 

San Simon

57.89

 

White Water Draw

24.32

 

DECEMBER 2008 - FEBRUARY 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

15.71

CD1

79.13

Upper Colorado

47.37

CD2

85.22

Little Colorado

32.43

CD3

83.04

Verde

43.24

CD4

53.91

Bill Williams

44.74

CD5

95.65

Agua Fria

42.11

CD6

97.39

Lower Gila

42.11

CD7

75.65

Salt

57.89

 

Lower Colorado

56.58

 

Upper Gila

26.32

 

Santa Cruz

18.42

 

San Pedro

22.22

 

Willcox Playa

16.22

 

San Simon

28.95

 

White Water Draw

18.92

 

SEPTEMBER 2008 FEBRUARY 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 northwestern and southeastern Arizona, significantly below average on the Little Colorado River watershed, and very much above average in southwestern Arizona, and on the Salt River watershed. Gila County continues to be the only area with near average temperatures for the past year. The northern half of the state was warmer than average, between the 71st and 81st percentiles, but the southern half of the state was much warmer than average, above the 87th percentile.

 

The 24 month period is still the wettest long-term period, with all watersheds, except the Virgin, Agua Fria and Santa Cruz, above the 40th percentile. Three watersheds, the upper Colorado, lower Gila and Salt are above the 75th percentile. Temperatures in all seven climate divisions are above the 76th percentile, and five climate divisions are above the 87th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

2.78

CD1

71.93

Upper Colorado

44.74

CD2

75.44

Little Colorado

21.05

CD3

80.70

Verde

31.58

CD4

44.30

Bill Williams

34.21

CD5

95.61

Agua Fria

34.21

CD6

99.12

Lower Gila

81.58

CD7

87.72

Salt

65.79

 

Lower Colorado

60.53

 

Upper Gila

50.00

 

Santa Cruz

28.95

 

San Pedro

52.63

 

Willcox Playa

35.14

 

San Simon

60.53

 

White Water Draw

40.54

 

MARCH 2008 FEBRUARY 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

76.99

Upper Colorado

75.68

CD2

88.50

Little Colorado

54.05

CD3

87.61

Verde

43.24

CD4

78.76

Bill Williams

45.95

CD5

93.81

Agua Fria

37.84

CD6

98.23

Lower Gila

81.08

CD7

96.46

Salt

81.08

 

Lower Colorado

62.16

 

Upper Gila

59.46

 

Santa Cruz

32.43

 

San Pedro

43.24

 

Willcox Playa

40.54

 

San Simon

70.27

 

White Water Draw

40.54

 

MARCH 2007 FEBRUARY 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 is very different between the northern and southern halves of the state. In northern Arizona, the upper Colorado and Little Colorado River watersheds had near average precipitation, while the Bill Williams, Verde and Agua Fria watersheds, had much lower than average precipitation. In southern Arizona, the upper and lower Gila, Salt and San Pedro watersheds were wetter than average, but the Santa Cruz was slightly drier than average. Six watersheds across the state were near average for precipitation. Temperatures over the three-year period remain extremely high with only the northwest climate division below the 87th percentile, and the two southern climate divisions above the 98th percentile.

 

The 48-month period continues to be the driest period, as the dry winter of 2008-2009 replaces the wet winter of 2004-2005. All watersheds except the Salt and lower Gila are below the 38th percentile. Nine watersheds are below the 23rd. The four-year temperatures continue to be extremely high, with the five climate divisions above the 90th percentile, and southern third of the state above the 99th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

2.94

CD1

76.34

Upper Colorado

44.44

CD2

86.61

Little Colorado

52.78

CD3

89.29

Verde

36.11

CD4

83.04

Bill Williams

22.22

CD5

91.07

Agua Fria

27.78

CD6

98.21

Lower Gila

75.00

CD7

98.21

Salt

72.22

 

Lower Colorado

50.00

 

Upper Gila

66.67

 

Santa Cruz

33.33

 

San Pedro

63.89

 

Willcox Playa

58.33

 

San Simon

50.00

 

White Water Draw

52.78

 

MARCH 2006 FEBRUARY 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

15.62

CD1

75.68

Upper Colorado

34.29

CD2

87.39

Little Colorado

22.86

CD3

90.09

Verde

11.43

CD4

90.09

Bill Williams

2.86

CD5

90.99

Agua Fria

2.86

CD6

99.10

Lower Gila

48.57

CD7

100.00

Salt

42.86

 

Lower Colorado

31.43

 

Upper Gila

28.57

 

Santa Cruz

5.71

 

San Pedro

20.00

 

Willcox Playa

22.86

 

San Simon

11.43

 

White Water Draw

37.14

 

MARCH 2005 FEBRUARY 2009 (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

February precipitation was near or slightly above average across northern and western Arizona, and slightly below average in the southeastern watersheds. Temperatures were near or slightly above average in the northern half of the state, and significantly warmer than average in the southern half.

 

The 3-month period of December through February was wetter than average for all but the southeastern third of the state. The two driest watersheds, Santa Cruz and Willcox Playa were below the 25th percentile. Temperatures for the three month period were near average in Gila County, slightly warmer than average along the western edge of the state, and well above average in the rest of the state.

 

The 6-month period precipitation was near average in the western half of the state, and in the Salt River basin. The Little Colorado River and the southeastern watersheds were drier than average, all below the 29th percentile. Five watersheds were below the 23rd percentile. Temperatures over the last six months were near average in Gila County, and well above average in all other counties. The warmest temperatures were in Yuma, Pinal and Maricopa counties, all above the 95th percentile.

 

The 12-month period precipitation was near or slightly below average in northwestern and southeastern Arizona, significantly below average on the Little Colorado River watershed, and very much above average in southwestern Arizona, and on the Salt River watershed. Gila County continues to be the only area with near average temperatures for the past year. The northern half of the state was warmer than average, between the 71st and 81st percentiles, but the southern half of the state was much warmer than average, above the 87th percentile.

 

The 24 month period is still the wettest long-term period, with all watersheds, except the Virgin, Agua Fria and Santa Cruz, above the 40th percentile. Three watersheds, the upper Colorado, lower Gila and Salt are above the 75th percentile. Temperatures in all seven climate divisions are above the 76th percentile, and five climate divisions are above the 87th percentile.

 

The 36-month period is very different between the northern and southern halves of the state. In northern Arizona, the upper Colorado and Little Colorado River watersheds had near average precipitation, while the Bill Williams, Verde and Agua Fria watersheds, had much lower than average precipitation. In southern Arizona, the upper and lower Gila, Salt and San Pedro watersheds were wetter than average, but the Santa Cruz was slightly drier than average. Six watersheds across the state were near average for precipitation. Temperatures over the three-year period remain extremely high with only the northwest climate division below the 87th percentile, and the two southern climate divisions above the 98th percentile.

 

The 48-month period continues to be the driest period, as the dry winter of 2008-2009 replaces the wet winter of 2004-2005. All watersheds except the Salt and lower Gila are below the 38th percentile. Nine watersheds are below the 23rd. The four-year temperatures continue to be extremely high, with the five climate divisions above the 90th percentile, and southern third of the state above the 99th percentile.