State Precipitation & Temperature Update for Arizona

Conditions through August 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 09/23/2008. The data are preliminary.


 

Precipitation Percentiles by Watershed (through August 2008)

 

Temperature Percentiles by Climate Division (through August 2008)


SHORT TERM CONDITIONS: 1-6 MONTHS

August was drier than average in the Little Colorado River watershed, near average on the lower Colorado, Agua Fria, Willcox, and Virgin River watersheds, and wetter than average in the other 10 watersheds. Overall, the monsoon has been very wet this year, especially in the southern half of the state. Temperatures have been near average in the southeast, slightly above average in Gila County, and well above average elsewhere in the state. The monsoon activity in August improved the three-month period of June through August, especially for the southern half of the state. The southern watersheds were all above the 80th percentile, and the northern watersheds were also well above average for precipitation, except the Virgin River, which has been exceptionally dry. Three-month temperatures were only slightly above average in the southern counties, but well above average along the lower Colorado River and in central Arizona. The six-month period precipitation, from March through August, was well above average in the southern half of the state and near or below average in the northern half of the state. The dryness in the north occurred as the winter storm activity abruptly stopped in mid February, and most of the monsoon activity remaining the southern half of the state. Six month temperatures were slightly above average in the northern half of the state, and well above average in the southern half of the state.

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

43.24

CD1

92.98

Upper Colorado

78.95

CD2

91.23

Little Colorado

39.47

CD3

91.23

Verde

73.68

CD4

74.56

Bill Williams

63.16

CD5

92.98

Agua Fria

50.00

CD6

88.60

Lower Gila

97.37

CD7

56.14

Salt

92.11

 

Lower Colorado

50.00

 

Upper Gila

86.84

 

Santa Cruz

78.95

 

San Pedro

60.53

 

Willcox Playa

57.89

 

San Simon

86.84

 

White Water Draw

60.53

 

AUGUST 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

16.67

CD1

89.38

Upper Colorado

76.32

CD2

82.02

Little Colorado

60.53

CD3

82.46

Verde

63.16

CD4

81.58

Bill Williams

65.79

CD5

92.11

Agua Fria

65.79

CD6

92.11

Lower Gila

100.00

CD7

65.79

Salt

89.47

 

Lower Colorado

65.79

 

Upper Gila

97.37

 

Santa Cruz

89.47

 

San Pedro

94.74

 

Willcox Playa

86.84

 

San Simon

97.37

 

White Water Draw

81.08

 

JUNE 2008 - AUGUST 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

71.68

Upper Colorado

42.11

CD2

66.67

Little Colorado

28.95

CD3

71.93

Verde

21.05

CD4

61.40

Bill Williams

36.84

CD5

81.58

Agua Fria

28.95

CD6

85.09

Lower Gila

92.11

CD7

81.14

Salt

65.79

 

Lower Colorado

57.89

 

Upper Gila

92.11

 

Santa Cruz

73.68

 

San Pedro

92.11

 

Willcox Playa

78.95

 

San Simon

86.84

 

White Water Draw

70.27

 

MARCH 2008 AUGUST 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 precipitation was near average in central Arizona, and above average along the upper Colorado as numerous winter storms brought heavy snowfall. South central Arizona was also wetter than average this year as both winter storms and monsoon activity moved across the state. Temperatures were warmer than average across the state, with the warmest conditions in the south.

 

The 24-month period was drier than average across the northern half of the state, with extreme variability in precipitation across the southern half of Arizona. The lower Gila watershed was at the 77th percentile, while the Santa Cruz was at the 36th percentile and the San Pedro was at the 50th. Storm activity over the two year period has been very isolated, leaving some locations very dry while nearby locations were extremely wet. Temperatures for the 24-month period continue to be much warmer than average everywhere, with the coolest area in the northwest.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

20.00

CD1

69.91

Upper Colorado

62.16

CD2

67.26

Little Colorado

40.54

CD3

76.99

Verde

56.76

CD4

81.86

Bill Williams

45.95

CD5

79.65

Agua Fria

48.65

CD6

86.73

Lower Gila

81.08

CD7

90.27

Salt

78.38

 

Lower Colorado

43.24

 

Upper Gila

59.46

 

Santa Cruz

62.16

 

San Pedro

67.57

 

Willcox Playa

55.56

 

San Simon

81.08

 

White Water Draw

43.24

 

SEPTEMBER 2008 AUGUST 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

5.88

CD1

73.66

Upper Colorado

50.00

CD2

83.93

Little Colorado

36.11

CD3

83.93

Verde

30.56

CD4

83.04

Bill Williams

22.22

CD5

88.39

Agua Fria

19.44

CD6

90.18

Lower Gila

77.78

CD7

92.86

Salt

55.56

 

Lower Colorado

44.44

 

Upper Gila

63.89

 

Santa Cruz

36.11

 

San Pedro

50.00

 

Willcox Playa

58.33

 

San Simon

61.11

 

White Water Draw

61.11

 

SEPTEMBER 2007 AUGUST 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 continues to be the driest period statewide, with only the upper and lower Gila basin and the Willcox Playa and Whitewater Draw in the southeast near average. All other watersheds are well below average, and four in northern Arizona are below the 12th percentile. Temperatures for the three year period were extremely high, with the southeast climate division being the warmest in 112 years, and Maricopa and Pinal counties were above the 97th percentile for temperature.

 

The 48-month period is much wetter than the 36-month period because it includes the wet winter of 2005. Watersheds in northern and western Arizona were all above the 61st percentile while the southeast watersheds were very dry, below the 36th percentile. Division 7 in the southeast continues to be the hottest 48-month period on record, and the other climate divisions are above the 76th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

6.06

CD1

76.58

Upper Colorado

25.71

CD2

88.29

Little Colorado

28.57

CD3

88.29

Verde

11.43

CD4

91.89

Bill Williams

5.71

CD5

88.74

Agua Fria

8.57

CD6

97.30

Lower Gila

48.57

CD7

100.00

Salt

28.57

 

Lower Colorado

22.86

 

Upper Gila

42.86

 

Santa Cruz

20.00

 

San Pedro

40.00

 

Willcox Playa

45.71

 

San Simon

25.71

 

White Water Draw

51.43

 

SEPTEMBER 2006 AUGUST 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

56.25

CD1

76.36

Upper Colorado

79.41

CD2

89.09

Little Colorado

50.00

CD3

87.27

Verde

61.76

CD4

94.55

Bill Williams

55.88

CD5

84.55

Agua Fria

47.06

CD6

92.73

Lower Gila

76.47

CD7

100.00

Salt

55.88

 

Lower Colorado

82.35

 

Upper Gila

58.82

 

Santa Cruz

26.47

 

San Pedro

35.29

 

Willcox Playa

47.06

 

San Simon

35.29

 

White Water Draw

52.94

 

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

 

September 2008 Arizona Drought Update (based on precipitation data through August 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

August: was drier than average in the Little Colorado River watershed, near average on the lower Colorado, Agua Fria, Willcox, and Virgin River watersheds, and wetter than average in the other 10 watersheds. Overall, the monsoon has been very wet this year, especially in the southern half of the state. Temperatures have been near average in the southeast, slightly above average in Gila County, and well above average elsewhere in the state.

 

The 3-month period: The monsoon activity in August improved the three-month period of June through August, especially for the southern half of the state. The southern watersheds were all above the 80th percentile, and the northern watersheds were also well above average for precipitation, except the Virgin River, which has been exceptionally dry. Three-month temperatures were only slightly above average in the southern counties, but well above average along the lower Colorado River and in central Arizona.

 

The 6-month period precipitation, from March through August, was much wetter than average in the southern half of the state and near or below average in the northern half of the state. The dryness in the north occurred as the winter storm activity abruptly stopped in mid February, and most of the monsoon activity remained in the southern half of the state. Six month temperatures were slightly above average in the northern half of the state, and much above average in the southern half of the state.

 

The 12-month period precipitation was near average in central Arizona, and above average along the upper Colorado as numerous winter storms brought heavy snowfall. South central Arizona was also wetter than average this year as summer thunderstorms moved across the southern part of the state. Temperatures were warmer than average across the state, with the warmest conditions in the south.

 

The 24-month period was drier than average across the northern half of the state, with extreme variability in precipitation across the southern half of Arizona. The lower Gila watershed was at the 77th percentile, while the Santa Cruz was at the 36th percentile and the San Pedro was at the 50th percentile. Storm activity over the two year period has been very isolated, leaving some locations very dry while nearby locations were extremely wet. Temperatures for the 24-month period continue to be much warmer than average everywhere, with the coolest area in the northwest.

 

The 36-month period continues to be the driest period statewide, with only the upper and lower Gila basin, Willcox Playa and Whitewater Draw in the southeast near average. All other watersheds are well below average, including four in northern Arizona below the 12th percentile. Temperatures for the three year period were extremely high, with the southeast climate division being the warmest in 112 years. Maricopa and Pinal counties were above the 97th percentile for temperature.

 

The 48-month period was much wetter than the 36-month period because it included the wet winter of 2005. Watersheds in northern and western Arizona were all above the 61st percentile, while the southeast watersheds were very dry, below the 36th percentile. Division 7 in the southeast continues to be the hottest 48-month period on record, and the other climate divisions are above the 76th percentile.