State Precipitation & Temperature Update for Arizona

Conditions through October 2006

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 12/10/2006. Note the San Pedro and Santa Cruz watersheds have preliminary data only.


 

Precipitation Percentiles by Watershed (through October 2006)

 

Temperature Percentiles by Climate Division (through October 2006)


SHORT TERM CONDITIONS: 1-6 MONTHS

October brought above-average rainfall to northwest Arizona, while the eastern half of the state had average rainfall, and the southwest watersheds had below average rainfall. Temperatures were below average in the northwest, average in the northeast, southeast, and southwest, and slightly above average in the central climate division. For the 3-month period of August through October, precipitation was above average everywhere in the state except the Virgin, Bill Williams, Santa Cruz, and San Simon watersheds which had average rainfall. The temperatures ranged from below average in the northwest and southeast to above average in the northeast and southwest. The 6-month period, May through October, which includes the wet monsoon, is still well above average for the southeast watershed, and above average for the rest of the state, except Bill Williams at the 33rd percentile. Temperatures were above the 75th percentile everywhere in the state for the summer and above the 95th percentile across the southern half of the state. The extreme temperatures generated an increased demand for the summer precipitation.

 

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

77.78

CD1

54.46

Upper Colorado

91.67

CD2

34.82

Little Colorado

75.00

CD3

33.93

Verde

77.78

CD4

38.39

Bill Williams

77.78

CD5

56.25

Agua Fria

59.72

CD6

73.21

Lower Gila

38.89

CD7

49.11

Salt

72.22

 

Lower Colorado

77.78

 

Upper Gila

63.89

 

Santa Cruz

33.33

 

San Pedro

69.44

 

Willcox Playa

55.56

 

San Simon

16.67

 

White Water Draw

63.89

 

OCTOBER 2006: 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

52.94

CD1

68.30

Upper Colorado

75.00

CD2

16.07

Little Colorado

61.11

CD3

32.59

Verde

61.11

CD4

23.21

Bill Williams

41.67

CD5

73.21

Agua Fria

77.78

CD6

67.86

Lower Gila

66.67

CD7

25.00

Salt

75.00

 

Lower Colorado

69.44

 

Upper Gila

77.78

 

Santa Cruz

50.00

 

San Pedro

75.00

 

Willcox Playa

86.11

 

San Simon

50.00

 

White Water Draw

83.33

 

AUGUST 2006 - OCTOBER 2006 (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

45.59

CD1

83.04

Upper Colorado

63.89

CD2

83.48

Little Colorado

72.22

CD3

91.96

Verde

61.11

CD4

79.46

Bill Williams

33.33

CD5

97.32

Agua Fria

58.33

CD6

97.32

Lower Gila

61.11

CD7

98.21

Salt

69.44

 

Lower Colorado

69.44

 

Upper Gila

83.33

 

Santa Cruz

77.78

 

San Pedro

94.44

 

Willcox Playa

100.00

 

San Simon

61.11

 

White Water Draw

80.00

 

MAY 2005 OCTOBER 2006 (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 most graphic indicator of the exceptionally dry winter of 2005, where most of the state had precipitation below the 25th percentile, and many watersheds in the west central part of the state were below the 15th percentile. The southeast fared only slightly better, with the San Pedro and Willcox as the only watersheds above the 50th percentile, mostly as a result of a very wet monsoon. The corresponding temperatures for the 1-year period remain extremely high, above the 85th percentile everywhere except the Colorado Plateau, which is above the 75th percentile. The southeast and south central areas were above the 95th percentile.

 

In contrast, the 2-year period shows the Colorado and Virgin River watersheds above the 75th percentile, and most of the rest of the state near or slightly above average, except the Santa Cruz and San Simon watersheds, which are at the 21st percentile. The 24-month temperatures were well above the 85th percentile everywhere except the Colorado Plateau, which dropped down to the 72nd percentile. The southeast climate division remains at the 99th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

27.27

CD1

75.68

Upper Colorado

20.00

CD2

89.19

Little Colorado

20.00

CD3

89.19

Verde

14.29

CD4

92.79

Bill Williams

8.57

CD5

91.89

Agua Fria

14.29

CD6

95.50

Lower Gila

14.29

CD7

99.10

Salt

17.14

 

Lower Colorado

22.86

 

Upper Gila

34.29

 

Santa Cruz

17.14

 

San Pedro

62.86

 

Willcox Playa

58.82

 

San Simon

11.43

 

White Water Draw

48.57

 

OCTOBER 2005 OCTOBER 2006 (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

90.32

CD1

72.73

Upper Colorado

79.41

CD2

90.91

Little Colorado

52.94

CD3

90.00

Verde

64.71

CD4

91.82

Bill Williams

58.82

CD5

88.18

Agua Fria

64.71

CD6

92.73

Lower Gila

67.65

CD7

99.09

Salt

55.88

 

Lower Colorado

82.35

 

Upper Gila

58.82

 

Santa Cruz

20.59

 

San Pedro

47.06

 

Willcox Playa

58.82

 

San Simon

20.59

 

White Water Draw

55.88

 

OCTOBER 2004 OCTOBER 2006 (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 rankings have changed little since the October update, with the western half of the state remaining near or above-average, while the eastern half of the state is near or below-average, with the Santa Cruz and San Simon watersheds continuing to be the driest. There is no change in the 36-month temperatures, with the entire state still above the 75th percentile. Climate divisions 4 and 7 in the southeast remain above the 95th percentile for temperature.

 

The 48-month precipitation shows slight improvement, particularly in the southern half of the state. The western watersheds are near or above-normal while the eastern watersheds are near or below-normal. The driest are the Little Colorado, Santa Cruz, San Simon and Willcox Playa. Recent months of monsoon moisture have not changed the excessive heat pattern evident over the past 4 years. Temperatures continue to be above the 95th percentile in the southeast and south central climate divisions, and above the 75th percentile elsewhere in the state.

 

 


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

93.55

CD1

76.15

Upper Colorado

69.70

CD2

89.91

Little Colorado

36.36

CD3

88.99

Verde

54.55

CD4

95.41

Bill Williams

57.58

CD5

88.07

Agua Fria

45.45

CD6

93.58

Lower Gila

60.61

CD7

99.08

Salt

48.48

 

Lower Colorado

84.85

 

Upper Gila

54.55

 

Santa Cruz

12.12

 

San Pedro

36.36

 

Willcox Playa

51.52

 

San Simon

18.18

 

White Water Draw

51.52

 

OCTOBER 2003 OCTOBER 2006 (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

78.70

Upper Colorado

68.75

CD2

90.74

Little Colorado

21.88

CD3

94.44

Verde

56.25

CD4

97.22

Bill Williams

56.25

CD5

92.59

Agua Fria

40.62

CD6

97.22

Lower Gila

62.50

CD7

100.00

Salt

37.50

 

Lower Colorado

81.25

 

Upper Gila

28.12

 

Santa Cruz

15.62

 

San Pedro

28.12

 

Willcox Playa

18.75

 

San Simon

25.00

 

White Water Draw

28.12

 

OCTOBER 2002 OCTOBER 2006 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

 

October 2006 Arizona Drought Update based on Precipitation (data through October 2006)

The following summary describes the heat and dryness across the state for the 1-, 3-, 6-, 12-, 24-, 36-, and 48-month periods. The Virgin River watershed has not yet reported precipitation data, and the Santa Cruz watershed has only a few stations reporting so far, so the results are preliminary.

 

SUMMARY

October brought above-average rainfall to northwest Arizona, while the eastern half of the state had average rainfall, and the southwest watersheds had below average rainfall. Temperatures were below average in the northwest, average in the northeast, southeast, and southwest, and slightly above average in the central climate division.

 

Three-month period Precipitation was above average everywhere in the state except the Virgin, Bill Williams, Santa Cruz, and San Simon watersheds which had average rainfall. The temperatures ranged from below average in the northwest and southeast to above average in the northeast and southwest.

 

Six-month period is still well above average for the southeast watershed, and above average for the rest of the state, except Bill Williams at the 33rd percentile. Temperatures were above the 75th percentile everywhere in the state for the summer and above the 95th percentile across the southern half of the state. The extreme temperatures generated an increased demand for the summer precipitation.

 

Twelve-month period - is the most graphic indicator of the exceptionally dry winter of 2005, where most of the state had precipitation below the 25th percentile, and many watersheds in the west central part of the state were below the 15th percentile. The southeast fared only slightly better, with the San Pedro and Willcox as the only watersheds above the 50th percentile, mostly as a result of a very wet monsoon. The corresponding temperatures for the 1-year period remain extremely high, above the 85th percentile everywhere except the Colorado Plateau, which is above the 75th percentile. The southeast and south central areas were above the 95th percentile.

 

Two-year period - shows the Colorado and Virgin River watersheds above the 75th percentile, and most of the rest of the state near or slightly above average, except the Santa Cruz and San Simon watersheds, which are at the 21st percentile. The 24-month temperatures were well above the 85th percentile everywhere except the Colorado Plateau, which dropped down to the 72nd percentile. The southeast climate division remains at the 99th percentile.

 

Three-year period - has changed little since the October update, with the western half of the state remaining near or above-average, while the eastern half of the state is near or below-average, with the Santa Cruz and San Simon watersheds continuing to be the driest. There is no change in the 36-month temperatures, with the entire state still above the 75th percentile. Climate divisions 4 and 7 in the southeast remain above the 95th percentile for temperature.

 

Four-year period - shows slight improvement, particularly in the southern half of the state. The western watersheds are near or above-normal while the eastern watersheds are near or below-normal. The driest are the Little Colorado, Santa Cruz, San Simon and Willcox Playa. Recent months of monsoon moisture have not changed the excessive heat pattern evident over the past 4 years. Temperatures continue to be above the 95th percentile in the southeast and south central climate divisions, and above the 75th percentile elsewhere in the state.