State Precipitation & Temperature Update for Arizona

Conditions through November 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. Not copied to summary yet need to proof. Current update is 12/31/2008. The data are preliminary.


 

Precipitation Percentiles by Watershed (through November 2008)

 

Temperature Percentiles by Climate Division (through November 2008)


SHORT TERM CONDITIONS: 1-6 MONTHS

November precipitation was near average across most of the state, with the central watersheds somewhat wetter than average, and the Santa Cruz and San Simon watersheds in southern Arizona, drier than average. Only two significant storm systems passed through Arizona in November. The first one, early in the month, brought scattered rain and snow showers to northern and central Arizona. The second system, over Thanksgiving, brought heavy snow and rain statewide. Temperatures were much warmer than average across the state in November. Only during the winter storms did temperatures fall to average or below average values. Temperatures were above the 95th percentile on the Colorado Plateau, and above the 83rd percentile elsewhere. The three month period, September through November, was much drier than average in all watersheds, except the lower Colorado River, due to an early end to the monsoon and a very dry October. Only the lower Colorado watershed was wetter than average. The dry conditions kept temperatures above average across the state. The six-month period precipitation, from June through November, continued to be wetter than average in the southern half of the state, and drier than average in the northern half of the state. The wet conditions in the south are due to the wet monsoon, which did not move into northern Arizona this year. Six month temperatures were much warmer than average, with all counties, except Gila, above the 81st percentile. Maricopa and Pinal counties were above the 98th percentile.

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

72.97

CD1

94.74

Upper Colorado

57.89

CD2

95.61

Little Colorado

50.00

CD3

94.74

Verde

71.05

CD4

91.23

Bill Williams

81.58

CD5

84.21

Agua Fria

76.32

CD6

83.77

Lower Gila

57.89

CD7

92.11

Salt

63.16

 

Lower Colorado

94.74

 

Upper Gila

44.74

 

Santa Cruz

26.32

 

San Pedro

44.74

 

Willcox Playa

45.95

 

San Simon

18.42

 

White Water Draw

47.37

 

NOVEMBER 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

22.22

CD1

91.15

Upper Colorado

21.05

CD2

82.89

Little Colorado

26.32

CD3

93.86

Verde

23.68

CD4

71.93

Bill Williams

34.21

CD5

91.23

Agua Fria

26.32

CD6

94.74

Lower Gila

28.95

CD7

76.32

Salt

21.05

 

Lower Colorado

63.16

 

Upper Gila

28.95

 

Santa Cruz

23.68

 

San Pedro

28.95

 

Willcox Playa

13.51

 

San Simon

18.42

 

White Water Draw

18.42

 

SEPTEMBER 2008 - NOVEMBER 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

11.11

CD1

81.86

Upper Colorado

39.47

CD2

84.21

Little Colorado

23.68

CD3

92.11

Verde

31.58

CD4

56.14

Bill Williams

55.26

CD5

94.74

Agua Fria

36.84

CD6

98.25

Lower Gila

92.11

CD7

86.84

Salt

65.79

 

Lower Colorado

57.89

 

Upper Gila

76.32

 

Santa Cruz

60.53

 

San Pedro

84.21

 

Willcox Playa

62.16

 

San Simon

76.32

 

White Water Draw

59.46

 

JUNE 2008 NOVEMBER 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 continues to be the wettest interval with 14 watersheds above the 48th percentile, and four watersheds above the 75th percentile. Only the Virgin watershed is drier than average. Temperatures were slightly warmer than average in northern Arizona and much warmer than average in southern Arizona.

 

The 24-month period was wetter than average in the Salt, upper and lower Gila and San Simon watersheds, near average in the upper Colorado, San Pedro, and Whitewater Draw watersheds, and drier than average in the other eight watersheds. The high variability is due to the difference in storm tracks between the winters of 2007 and 2008, and monsoon activity in the summers of 2007 and 2008. Temperatures for the 24-month period are once again above the 75th percentile across the state, with the warmest temperatures in Maricopa, Pinal, and the southeastern counties.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

17.14

CD1

68.58

Upper Colorado

72.97

CD2

61.06

Little Colorado

54.05

CD3

76.99

Verde

48.65

CD4

49.12

Bill Williams

54.05

CD5

77.88

Agua Fria

54.05

CD6

88.50

Lower Gila

91.89

CD7

78.32

Salt

86.49

 

Lower Colorado

67.57

 

Upper Gila

81.08

 

Santa Cruz

62.16

 

San Pedro

70.27

 

Willcox Playa

51.35

 

San Simon

78.38

 

White Water Draw

54.05

 

DECEMBER 2008 NOVEMBER 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

2.94

CD1

75.89

Upper Colorado

41.67

CD2

85.71

Little Colorado

33.33

CD3

88.39

Verde

25.00

CD4

83.48

Bill Williams

19.44

CD5

88.39

Agua Fria

22.22

CD6

95.54

Lower Gila

83.33

CD7

92.86

Salt

61.11

 

Lower Colorado

38.89

 

Upper Gila

66.67

 

Santa Cruz

27.78

 

San Pedro

44.44

 

Willcox Playa

36.11

 

San Simon

61.11

 

White Water Draw

44.44

 

DECEMBER 2007 NOVEMBER 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 remains the driest long term period statewide, with the driest watersheds in central Arizona. There has been some improvement as there are now four watersheds above the 42nd percentile, and only five are below the 25th percentile. Temperatures are still much warmer than average for the 36-month period, with the southern half of the state the warmest.

 

The 48-month period has nine watersheds drier than average, five watersheds near average, and one (lower Gila) wetter than average. The driest watersheds continue to be the Santa Cruz in southeastern Arizona, and the Bill Williams in west central Arizona, both below the 24th percentile. The 48-month temperatures are still well above average in all climate divisions, with the southeastern and south central divisions at the 100th percentile, the warmest 48-month period since 1895.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

3.03

CD1

77.93

Upper Colorado

31.43

CD2

88.29

Little Colorado

22.86

CD3

91.89

Verde

14.29

CD4

90.99

Bill Williams

8.57

CD5

90.09

Agua Fria

8.57

CD6

97.30

Lower Gila

62.86

CD7

99.10

Salt

45.71

 

Lower Colorado

28.57

 

Upper Gila

54.29

 

Santa Cruz

28.57

 

San Pedro

42.86

 

Willcox Playa

48.57

 

San Simon

28.57

 

White Water Draw

40.00

 

DECEMBER 2006 NOVEMBER 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

29.03

CD1

76.36

Upper Colorado

55.88

CD2

89.09

Little Colorado

38.24

CD3

91.82

Verde

38.24

CD4

92.73

Bill Williams

17.65

CD5

88.18

Agua Fria

26.47

CD6

100.00

Lower Gila

67.65

CD7

100.00

Salt

52.94

 

Lower Colorado

47.06

 

Upper Gila

52.94

 

Santa Cruz

23.53

 

San Pedro

38.24

 

Willcox Playa

38.24

 

San Simon

29.41

 

White Water Draw

47.06

 

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

 

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

November precipitation was near average across most of the state, with the central watersheds somewhat wetter than average, and the Santa Cruz and San Simon watersheds in southern Arizona, drier than average. Only two significant storm systems passed through Arizona in November. The first one, early in the month, brought scattered rain and snow showers to northern and central Arizona. The second system, over Thanksgiving, brought heavy snow and rain statewide. Temperatures were much warmer than average across the state in November. Only during the winter storms did temperatures fall to average or below average values. Temperatures were above the 95th percentile on the Colorado Plateau, and above the 83rd percentile elsewhere.

 

The 3-month period, September through November, was much drier than average in all watersheds, except the lower Colorado River, due to an early end to the monsoon and a very dry October. Only the lower Colorado watershed was wetter than average. The dry conditions kept temperatures above average across the state.

 

The 6-month period, from June through November, continued to be wetter than average in the southern half of the state, and drier than average in the northern half of the state. The wet conditions in the south are due to the wet monsoon, which did not move into northern Arizona this year. Six month temperatures were much warmer than average, with all counties, except Gila, above the 81st percentile. Maricopa and Pinal counties were above the 98th percentile

 

The 12-month period continues to be the wettest interval with 14 watersheds above the 48th percentile, and four watersheds above the 75th percentile. Only the Virgin watershed is drier than average. Temperatures were slightly warmer than average in northern Arizona and much warmer than average in southern Arizona.

 

The 24-month period was wetter than average in the Salt, upper and lower Gila and San Simon watersheds, near average in the upper Colorado, San Pedro, and Whitewater Draw watersheds, and drier than average in the other eight watersheds. The high variability is due to the difference in storm tracks between the winters of 2007 and 2008, and monsoon activity in the summers of 2007 and 2008. Temperatures for the 24-month period are once again above the 75th percentile across the state, with the warmest temperatures in Maricopa, Pinal, and the southeastern counties.

 

The 36-month period remains the driest long term period statewide, with the driest watersheds in central Arizona. There has been some improvement as there are now four watersheds above the 42nd percentile, and only five are below the 25th percentile. Temperatures are still much warmer than average for the 36-month period, with the southern half of the state the warmest.

 

The 48-month period has nine watersheds drier than average, five watersheds near average, and one (lower Gila) wetter than average. The driest watersheds continue to be the Santa Cruz in southeastern Arizona, and the Bill Williams in west central Arizona, both below the 24th percentile. The 48-month temperatures are still well above average in all climate divisions, with the southeastern and south central divisions at the 100th percentile, the warmest 48-month period since 1895.