State Precipitation & Temperature Update for Arizona

Conditions through December 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 01/24/2009. The data are preliminary.


Precipitation Percentiles by Watershed (through December 2008)

 

Temperature Percentiles by Climate Division (through December 2008)


SHORT TERM CONDITIONS: 1-6 MONTHS

December was very wet in the northern two thirds of the state, above the 75th percentile. Precipitation was near average in the southern watersheds, and slightly above average on the upper Gila and San Simon. Precipitation fell on 19 days in December, with snow on 14 of those days, as a series of winter storms moved across the state. The storms dropped temperatures in the state to near or below average everywhere except on the Colorado Plateau. The three-month period of October through December has also been wetter than average for the northern half of the state. The upper and lower Gila, San Simon, and San Pedro watersheds had near average precipitation, while the Santa Cruz, Whitewater Draw, and Willcox Playa were drier than average. Temperatures for the three month period were well above average, especially on the Colorado Plateau, which was at the 88th percentile. The six-month period precipitation was near or above average across the state, with the Salt, lower Gila and San Simon watersheds above the 86th percentile. Six-month temperatures were up above the 75th percentile except in Gila county. Gila county had near average temperatures due to both the wet monsoon and the recent cold winter storms.

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

63.16

CD1

29.82

Upper Colorado

97.37

CD2

62.72

Little Colorado

86.84

CD3

28.95

Verde

86.49

CD4

26.32

Bill Williams

89.47

CD5

52.63

Agua Fria

84.21

CD6

47.37

Lower Gila

76.32

CD7

51.32

Salt

89.47

 

Lower Colorado

84.21

 

Upper Gila

65.79

 

Santa Cruz

57.89

 

San Pedro

58.33

 

Willcox Playa

52.63

 

San Simon

73.68

 

White Water Draw

55.26

 

DECEMBER 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

37.84

CD1

80.53

Upper Colorado

84.21

CD2

88.60

Little Colorado

60.53

CD3

72.81

Verde

72.97

CD4

67.98

Bill Williams

78.95

CD5

71.93

Agua Fria

73.68

CD6

81.58

Lower Gila

55.26

CD7

82.46

Salt

86.84

 

Lower Colorado

81.58

 

Upper Gila

44.74

 

Santa Cruz

18.42

 

San Pedro

44.44

 

Willcox Playa

24.32

 

San Simon

42.11

 

White Water Draw

28.95

 

OCTOBER 2008 - DECEMBER 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

15.28

CD1

80.09

Upper Colorado

78.95

CD2

84.21

Little Colorado

44.74

CD3

84.21

Verde

59.46

CD4

45.61

Bill Williams

71.05

CD5

92.98

Agua Fria

60.53

CD6

94.74

Lower Gila

94.74

CD7

75.00

Salt

89.47

 

Lower Colorado

76.32

 

Upper Gila

84.21

 

Santa Cruz

55.26

 

San Pedro

77.78

 

Willcox Playa

51.35

 

San Simon

86.84

 

White Water Draw

56.76

 

JULY 2008 DECEMBER 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 was wetter than average across northern and much of southern Arizona, with near average precipitation in central Arizona. Only the Santa Cruz, Willcox Playa and Whitewater Draw watersheds were drier than average. The past year has been slightly warmer than average in northern Arizona, and much warmer than average in southern Arizona, with near average temperatures in Gila county.

 

The 24 month period was also wetter than average across northern and south central Arizona. Central and southeastern Arizona have had near average precipitation over the past two years. The Bill Williams and Agua Fria watersheds have been drier than average. Temperatures in the past two years have been well above average in all areas of the state, with the warmest temperatures in Maricopa and Pinal counties.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

5.56

CD1

67.26

Upper Colorado

81.58

CD2

66.81

Little Colorado

44.74

CD3

76.11

Verde

52.63

CD4

46.02

Bill Williams

52.63

CD5

84.07

Agua Fria

50.00

CD6

92.04

Lower Gila

86.84

CD7

85.84

Salt

84.21

 

Lower Colorado

65.79

 

Upper Gila

71.05

 

Santa Cruz

39.47

 

San Pedro

65.79

 

Willcox Playa

31.58

 

San Simon

78.95

 

White Water Draw

34.21

 

JANUARY 2008 DECEMBER 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

2.86

CD1

77.68

Upper Colorado

64.86

CD2

86.61

Little Colorado

48.65

CD3

86.61

Verde

40.54

CD4

79.46

Bill Williams

37.84

CD5

88.84

Agua Fria

37.84

CD6

98.21

Lower Gila

89.19

CD7

93.75

Salt

78.38

 

Lower Colorado

51.35

 

Upper Gila

64.86

 

Santa Cruz

40.54

 

San Pedro

54.05

 

Willcox Playa

43.24

 

San Simon

70.27

 

White Water Draw

43.24

 

JANUARY 2006 DECEMBER 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 three watersheds with above average precipitation, five with near normal precipitation, four with slightly below average precipitation, and three very dry watersheds, below the 15th percentile. Temperatures over the three-year period are extremely high with only the northwest climate division below the 80th percentile, and the southern climate divisions above the 97th percentile.

 

The 48-month period is now the driest period, with eight watersheds below average, five watersheds near average, and only two watersheds with above average precipitation. The four-year temperatures are extremely high, with the southern third of the state above the 99th percentile, and the coolest climate division, Mohave county in the northwest, above the 75th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

5.88

CD1

78.38

Upper Colorado

41.67

CD2

89.19

Little Colorado

44.44

CD3

88.29

Verde

30.56

CD4

87.39

Bill Williams

11.11

CD5

90.99

Agua Fria

13.89

CD6

97.30

Lower Gila

69.44

CD7

99.10

Salt

61.11

 

Lower Colorado

38.89

 

Upper Gila

61.11

 

Santa Cruz

30.56

 

San Pedro

55.56

 

Willcox Playa

55.56

 

San Simon

33.33

 

White Water Draw

47.22

 

JANUARY 2005 DECEMBER 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

28.12

CD1

75.45

Upper Colorado

62.86

CD2

90.91

Little Colorado

42.86

CD3

87.73

Verde

40.00

CD4

91.82

Bill Williams

14.29

CD5

89.09

Agua Fria

22.86

CD6

99.09

Lower Gila

65.71

CD7

100.00

Salt

54.29

 

Lower Colorado

51.43

 

Upper Gila

51.43

 

Santa Cruz

20.00

 

San Pedro

34.29

 

Willcox Playa

37.14

 

San Simon

31.43

 

White Water Draw

45.71

 

JANUARY 2004 DECEMBER 2008 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

 

January 2008 Arizona Drought Update based on precipitation data through December 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

December was very wet in the northern two thirds of the state, above the 75th percentile. Precipitation was near average in the southern watersheds, and slightly above average on the upper Gila and San Simon. Precipitation fell on 19 days in December, with snow on 14 of those days, as a series of winter storms moved across the state. The storms dropped temperatures in the state to near or below average everywhere except on the Colorado Plateau.

 

The 3-month period of October through December has also been wetter than average for the northern half of the state. The upper and lower Gila, San Simon, and San Pedro watersheds had near average precipitation, while the Santa Cruz, Whitewater Draw, and Willcox Playa were drier than average. Temperatures for the three month period were well above average, especially on the Colorado Plateau, which was at the 88th percentile.

 

The 6-month period precipitation was near or above average across the state, with the Salt, lower Gila and San Simon watersheds above the 86th percentile. Six-month temperatures were up above the 75th percentile except in Gila county. Gila county had near average temperatures due to both the wet monsoon and the recent cold winter storms.

 

The 12-month period was wetter than average across northern and much of southern Arizona, with near average precipitation in central Arizona. Only the Santa Cruz, Willcox Playa and Whitewater Draw watersheds were drier than average. The past year has been slightly warmer than average in northern Arizona, and much warmer than average in southern Arizona, with near average temperatures in Gila county.

 

The 24 month period was also wetter than average across northern and south central Arizona. Central and southeastern Arizona have had near average precipitation over the past two years. The Bill Williams and Agua Fria watersheds have been drier than average. Temperatures in the past two years have been well above average in all areas of the state, with the warmest temperatures in Maricopa and Pinal counties.

 

The 36-month period has three watersheds with above average precipitation, five with near normal precipitation, four with slightly below average precipitation, and three very dry watersheds, below the 15th percentile. Temperatures over the three-year period are extremely high with only the northwest climate division below the 80th percentile, and the southern climate divisions above the 97th percentile.

 

The 48-month period is now the driest period, with eight watersheds below average, five watersheds near average, and only two watersheds with above average precipitation. The four-year temperatures are extremely high, with the southern third of the state above the 99th percentile, and the coolest climate division, Mohave county in the northwest, above the 75th percentile.