State Precipitation & Temperature Update for Arizona

Conditions through October 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 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 11/27/2008. The data are preliminary.


 

Precipitation Percentiles by Watershed (through October 2008)

 

Temperature Percentiles by Climate Division (through October 2008)


SHORT TERM CONDITIONS: 1-6 MONTHS

October was dry everywhere in Arizona. The western watersheds were below the 15th percentile, while all the eastern watersheds were below the 40th percentile, except the San Pedro, which was at the 42nd percentile for precipitation. Only two storm systems moved through the state in October, and the majority of rainfall fell in the southeast and eastern mountains. Temperatures were slightly above average, with the warmest temperatures in western Arizona. The three month period was drier than average in all but three watersheds. The upper and lower Gila and San Simon River watersheds all had above-average precipitation for the August through October period. Eleven watersheds were below the 40th percentile and seven were below the 25th percentile. The dry conditions kept temperatures above average in the western and northern parts of the state. The six-month period precipitation, from May through October, was wetter than average in the southern half of the state, and average or drier than average in the northern half of the state. This year the monsoon was very active in southern Arizona, and weak in northern Arizona. Six month temperatures were much warmer than average, above the 96th percentile, in Maricopa and Pinal counties; above the 92nd percentile in La Paz and Yuma Counties; above the 79th percentile in Yavapai county, and below the 74th percentile elsewhere.

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

6.58

CD1

76.32

Upper Colorado

13.16

CD2

72.81

Little Colorado

28.95

CD3

78.95

Verde

10.53

CD4

69.74

Bill Williams

13.16

CD5

79.39

Agua Fria

10.53

CD6

85.53

Lower Gila

13.16

CD7

68.86

Salt

28.95

 

Lower Colorado

11.84

 

Upper Gila

18.42

 

Santa Cruz

13.16

 

San Pedro

42.11

 

Willcox Playa

15.79

 

San Simon

21.05

 

White Water Draw

18.42

 

OCTOBER 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

11.11

CD1

86.73

Upper Colorado

31.58

CD2

81.14

Little Colorado

10.53

CD3

86.84

Verde

18.42

CD4

71.49

Bill Williams

23.68

CD5

92.11

Agua Fria

15.79

CD6

92.98

Lower Gila

76.32

CD7

54.39

Salt

52.63

 

Lower Colorado

23.68

 

Upper Gila

65.79

 

Santa Cruz

28.95

 

San Pedro

39.47

 

Willcox Playa

21.05

 

San Simon

78.95

 

White Water Draw

26.32

 

AUGUST 2008 - OCTOBER 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

5.56

CD1

73.45

Upper Colorado

47.37

CD2

66.67

Little Colorado

36.84

CD3

79.82

Verde

44.74

CD4

41.67

Bill Williams

36.84

CD5

92.98

Agua Fria

39.47

CD6

96.49

Lower Gila

94.74

CD7

71.05

Salt

81.58

 

Lower Colorado

50.00

 

Upper Gila

89.47

 

Santa Cruz

68.42

 

San Pedro

89.47

 

Willcox Playa

60.53

 

San Simon

84.21

 

White Water Draw

54.05

 

MAY 2008 OCTOBER 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 is the wettest interval with 14 watersheds above the 40th percentile, seven watersheds above the 67th percentile, and three watersheds above the 83rd percentile. The wettest watersheds were in southern Arizona. The Virgin watershed, in northwestern Arizona, was below the 9th percentile. Temperatures continued to be warmer than average across the state, with the warmest conditions in the south.

 

The 24-month period has a large variation of conditions in the watersheds. Two watersheds are below the 14th percentile, six are near the 50th percentile, and one watershed is above the 80th percentile. Temperatures for the 24-month period continue to be above the 75th percentile across the state, with the coolest temperatures in Gila and Mohave counties, and the warmest temperatures in Maricopa, Pinal, and the southeastern counties.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

8.57

CD1

71.68

Upper Colorado

72.97

CD2

67.26

Little Colorado

45.95

CD3

77.88

Verde

45.95

CD4

70.80

Bill Williams

40.54

CD5

83.63

Agua Fria

48.65

CD6

88.50

Lower Gila

91.89

CD7

90.27

Salt

83.78

 

Lower Colorado

48.65

 

Upper Gila

81.08

 

Santa Cruz

67.57

 

San Pedro

67.57

 

Willcox Playa

55.56

 

San Simon

83.78

 

White Water Draw

56.76

 

NOVEMBER 2008 OCTOBER 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

3.03

CD1

75.89

Upper Colorado

44.44

CD2

87.05

Little Colorado

30.56

CD3

90.18

Verde

19.44

CD4

83.04

Bill Williams

13.89

CD5

90.18

Agua Fria

16.67

CD6

95.54

Lower Gila

80.56

CD7

96.43

Salt

50.00

 

Lower Colorado

27.78

 

Upper Gila

50.00

 

Santa Cruz

22.22

 

San Pedro

44.44

 

Willcox Playa

33.33

 

San Simon

55.56

 

White Water Draw

47.22

 

NOVEMBER 2007 OCTOBER 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 the driest long term period statewide, with the driest watersheds in west central Arizona. All but two watersheds are below the 41st percentile, and seven watersheds are below the 23rd percentile. Temperatures for the three year period continue to be very warm, with six of the seven climate divisions above the 89th percentile, and two above the 98th percentile. The southeast climate division continues to be the warmest 3-year period in 112 years.

 

The 48-month period has two watersheds (lower Gila and upper Colorado) wetter than average, seven watersheds near average, and six watersheds drier than average. The driest watersheds are the Santa Cruz in southeastern Arizona, and the Bill Williams in west central Arizona, both below the 23rd percentile. The 48-month temperatures are still well above average in all climate divisions, with the southeastern division at the 100th percentile, the warmest 48-month period since 1895.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

3.03

CD1

78.38

Upper Colorado

25.71

CD2

89.19

Little Colorado

17.14

CD3

89.19

Verde

11.43

CD4

91.89

Bill Williams

5.71

CD5

91.89

Agua Fria

11.43

CD6

98.20

Lower Gila

48.57

CD7

100.00

Salt

28.57

 

Lower Colorado

14.29

 

Upper Gila

37.14

 

Santa Cruz

22.86

 

San Pedro

40.00

 

Willcox Playa

42.86

 

San Simon

28.57

 

White Water Draw

40.00

 

NOVEMBER 2006 OCTOBER 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

32.26

CD1

75.45

Upper Colorado

67.65

CD2

90.00

Little Colorado

41.18

CD3

88.18

Verde

41.18

CD4

91.82

Bill Williams

20.59

CD5

88.18

Agua Fria

32.35

CD6

98.18

Lower Gila

76.47

CD7

100.00

Salt

55.88

 

Lower Colorado

52.94

 

Upper Gila

50.00

 

Santa Cruz

20.59

 

San Pedro

38.24

 

Willcox Playa

41.18

 

San Simon

35.29

 

White Water Draw

52.94

 

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

 

November 2008 Arizona Drought Update (based on precipitation data through October 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

October was dry everywhere in Arizona. The western watersheds were below the 15th percentile, while all the eastern watersheds were below the 40th percentile, except the San Pedro, which was at the 42nd percentile for precipitation. Only two storm systems moved through the state in October, and the majority of rainfall fell in the southeast and eastern mountains. Temperatures were slightly above average, with the warmest temperatures in western Arizona.

 

The 3-month period was drier than average in all but three watersheds. The upper and lower Gila and San Simon River watersheds all had above-average precipitation for the August through October period. Eleven watersheds were below the 40th percentile and seven were below the 25th percentile. The dry conditions kept temperatures above average in the western and northern parts of the state.

 

The 6-month period precipitation, from May through October, was wetter than average in the southern half of the state, and average or drier than average in the northern half of the state. This year the monsoon was very active in southern Arizona, and weak in northern Arizona. Six month temperatures were much warmer than average, above the 96th percentile, in Maricopa and Pinal counties; above the 92nd percentile in La Paz and Yuma Counties; above the 79th percentile in Yavapai county, and below the 74th percentile elsewhere.

 

The 12-month period is the wettest interval with 14 watersheds above the 40th percentile, seven watersheds above the 67th percentile, and three watersheds above the 83rd percentile. The wettest watersheds were in southern Arizona. The Virgin watershed, in northwestern Arizona, was below the 9th percentile. Temperatures continued to be warmer than average across the state, with the warmest conditions in the south.

 

The 24-month period has a large variation of conditions in the watersheds. Two watersheds are below the 14th percentile, six are near the 50th percentile, and one watershed is above the 80th percentile. Temperatures for the 24-month period continue to be above the 75th percentile across the state, with the coolest temperatures in Gila and Mohave counties, and the warmest temperatures in Maricopa, Pinal, and the southeastern counties.

 

The 36-month period is the driest long term period statewide, with the driest watersheds in west central Arizona. All but two watersheds are below the 41st percentile, and seven watersheds are below the 23rd percentile. Temperatures for the three year period continue to be very warm, with six of the seven climate divisions above the 89th percentile, and two above the 98th percentile. The southeast climate division continues to be the warmest 3-year period in 112 years.

 

The 48-month period has two watersheds (lower Gila and upper Colorado) wetter than average, seven watersheds near average, and six watersheds drier than average. The driest watersheds are the Santa Cruz in southeastern Arizona, and the Bill Williams in west central Arizona, both below the 23rd percentile. The 48-month temperatures are still well above average in all climate divisions, with the southeastern division at the 100th percentile, the warmest 48-month period since 1895.