State Precipitation & Temperature Update for Arizona

Conditions through July 2007

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 8/25/2007. The data are preliminary.


 

Precipitation Percentiles by Watershed (through July 2007)

 

Temperature Percentiles by Climate Division (through July 2007)


SHORT TERM CONDITIONS: 1-6 MONTHS

July is generally a wet month across Arizona, and this year was no exception for most of the state, except the northwest corner, which received slightly below-average rainfall. The monsoon, so far, has been extremely wet across most of the state. The southeast, which normally has the wettest summer has been slightly below the central and eastern mountain basins. Temperatures across the state were well above average, with only the lower Colorado River division below the 95th percentile. For the 3-month period of May through July, precipitation was also well above average, for most of the state. Only the Virgin River basin and the southeast watersheds were near or below their May-July averages. The wet conditions helped to decrease temperatures below the 95th percentile, where they had been through the drier months. The 6-month period spans the dry winter from February through the wet summer month of July, with most watersheds either slightly above or slightly below average precipitation. Temperatures were above the 85th percentile everywhere in the state, and above the 95thth percentile in the central and northeastern climate divisions.

 

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

38.89

CD1

97.35

Upper Colorado

91.89

CD2

98.23

Little Colorado

89.19

CD3

99.12

Verde

91.89

CD4

99.12

Bill Williams

81.08

CD5

92.04

Agua Fria

91.89

CD6

99.12

Lower Gila

97.30

CD7

96.46

Salt

94.59

 

Lower Colorado

94.59

 

Upper Gila

72.97

 

Santa Cruz

75.68

 

San Pedro

67.57

 

Willcox Playa

62.16

 

San Simon

91.89

 

White Water Draw

55.56

 

JULY 2007: 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

93.81

Upper Colorado

86.49

CD2

94.69

Little Colorado

81.08

CD3

93.81

Verde

81.08

CD4

98.23

Bill Williams

64.86

CD5

89.38

Agua Fria

81.08

CD6

94.69

Lower Gila

97.30

CD7

94.69

Salt

78.38

 

Lower Colorado

94.59

 

Upper Gila

67.57

 

Santa Cruz

70.27

 

San Pedro

54.05

 

Willcox Playa

56.76

 

San Simon

91.89

 

White Water Draw

55.56

 

MAY 2006 - JULY 2007 (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

92.92

Upper Colorado

43.24

CD2

96.46

Little Colorado

37.84

CD3

96.46

Verde

27.03

CD4

94.69

Bill Williams

18.92

CD5

92.04

Agua Fria

35.14

CD6

95.58

Lower Gila

70.27

CD7

94.69

Salt

29.73

 

Lower Colorado

64.86

 

Upper Gila

45.95

 

Santa Cruz

37.84

 

San Pedro

40.54

 

Willcox Playa

52.78

 

San Simon

56.76

 

White Water Draw

58.33

 

FEBRUARY 2006 JULY 2007 (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 reflects winter of 2006-07 and the end of the 2006 monsoon season. For all watersheds in the state except White Water Draw and Willcox Playa in the southeast, the 12 month period was very dry. The Upper Gila had average precipitation at the 50th percentile, and the rest of the state was below that, with three watersheds below the 26th percentile. The twelve month period was relatively cooler than the other periods with no climate division above the 92nd percentile. However, with all climate divisions above the 79th percentile, it was still much warmer than the average.

The two-year period precipitation continues to be well below-average for all watersheds except White Water Draw. The rest of the state is below the 46th percentile and 11 watersheds are at or below the 20th percentile. This period includes two dry winters, one normal monsoon in 2006 and a dry monsoon in 2005. The entire state was very warm during the past 24 months, with a north-south temperature gradient. The high temperatures have increased the evaporative demand for water, reducing the water available for recharge.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

12.12

CD1

81.25

Upper Colorado

44.44

CD2

79.91

Little Colorado

30.56

CD3

85.71

Verde

25.00

CD4

85.71

Bill Williams

5.56

CD5

82.14

Agua Fria

36.11

CD6

87.05

Lower Gila

44.44

CD7

91.07

Salt

33.33

 

Lower Colorado

44.44

 

Upper Gila

50.00

 

Santa Cruz

27.78

 

San Pedro

47.22

 

Willcox Playa

60.00

 

San Simon

38.89

 

White Water Draw

66.67

 

AUGUST 2006 JULY 2007 (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

18.18

CD1

78.38

Upper Colorado

14.29

CD2

90.09

Little Colorado

17.14

CD3

90.99

Verde

8.57

CD4

91.89

Bill Williams

5.71

CD5

90.09

Agua Fria

5.71

CD6

97.30

Lower Gila

11.43

CD7

100.00

Salt

8.57

 

Lower Colorado

34.29

 

Upper Gila

20.00

 

Santa Cruz

14.29

 

San Pedro

34.29

 

Willcox Playa

45.71

 

San Simon

5.71

 

White Water Draw

54.29

 

AUGUST 2005 JULY 2007 (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 period adds a wet winter to the two dry winters, and a second dry monsoon, resulting in a pattern of drier than average conditions in the southern half of the state, average precipitation in the central watersheds, and wetter than average conditions in the northern and western watersheds. The 36-month-temperature pattern continues to show the southeast climate division as the hottest in 37 years and all but the northwestern climate division are above the 88th percentile.

 

The 48-month map continues to show much drier than average conditions everywhere except the northernmost and westernmost watersheds. Six of the eastern and central watersheds are below the 25th percentile. Temperatures in the southern climate divisions are above the 95th percentile, and the northern and western climate divisions are above the 77th percentile.

 


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

75.76

CD1

74.55

Upper Colorado

76.47

CD2

88.18

Little Colorado

41.18

CD3

88.18

Verde

52.94

CD4

94.55

Bill Williams

50.00

CD5

85.45

Agua Fria

41.18

CD6

94.55

Lower Gila

64.71

CD7

99.09

Salt

41.18

 

Lower Colorado

82.35

 

Upper Gila

38.24

 

Santa Cruz

8.82

 

San Pedro

17.65

 

Willcox Playa

41.18

 

San Simon

20.59

 

White Water Draw

47.06

 

AUGUST 2004 JULY 2007 (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

64.52

CD1

77.98

Upper Colorado

66.67

CD2

89.91

Little Colorado

21.21

CD3

94.50

Verde

36.36

CD4

95.41

Bill Williams

39.39

CD5

88.07

Agua Fria

21.21

CD6

98.17

Lower Gila

51.52

CD7

100.00

Salt

27.27

 

Lower Colorado

75.76

 

Upper Gila

24.24

 

Santa Cruz

9.09

 

San Pedro

21.21

 

Willcox Playa

27.27

 

San Simon

24.24

 

White Water Draw

36.36

 

AUGUST 2003 JULY 2007 (48-month): percentiles of temperature, and precipitation for the 15 Arizona watersheds and percentiles of temperature for the 7 climate divisions.

 

August 2007 Arizona Drought Update based on Precipitation (data through July 2007)

The following summary describes the heat and dryness across the state for the 1-, 3-, 6-, 12-, 24-, 36-, and 48-month periods.

 

SUMMARY

July is generally a wet month across Arizona, and this year was no exception for most of the state, except the northwest corner, which received slightly below-average rainfall. The monsoon, so far, has been extremely wet across most of the state. The southeast, which normally has the wettest summer has been slightly below the central and eastern mountain basins. Temperatures across the state were well above average, with only the lower Colorado River division below the 95th percentile.

 

Three-month period For the 3-month period of May through July, precipitation was also well above average, for most of the state. Only the Virgin River basin and the southeast watersheds were near or below their May-July averages. The wet conditions helped to decrease temperatures below the 95th percentile, where they had been through the drier months.

 

Six-month period spans the dry winter from February through the wet summer month of July, with most watersheds either slightly above or slightly below average precipitation. Temperatures were above the 85th percentile everywhere in the state, and above the 95thth percentile in the central and northeastern climate divisions.

 

Twelve-month period reflects winter of 2006-07 and the end of the 2006 monsoon season. For all watersheds in the state except White Water Draw and Willcox Playa in the southeast, the 12 month period was very dry. The Upper Gila had average precipitation at the 50th percentile, and the rest of the state was below that, with three watersheds below the 26th percentile. The twelve month period was relatively cooler than the other periods with no climate division above the 92nd percentile. However, with all climate divisions above the 79th percentile, it was still much warmer than the average.

Two-year period - precipitation continues to be well below-average for all watersheds except White Water Draw. The rest of the state is below the 46th percentile and 11 watersheds are at or below the 20th percentile. This period includes two dry winters, one normal monsoon in 2006 and a dry monsoon in 2005. The entire state was very warm during the past 24 months, with a north-south temperature gradient. The high temperatures have increased the evaporative demand for water, reducing the water available for recharge.

 

Three-year period - The 36-month precipitation period adds a wet winter to the two dry winters, and a second dry monsoon, resulting in a pattern of drier than average conditions in the southern half of the state, average precipitation in the central watersheds, and wetter than average conditions in the northern and western watersheds. The 36-month-temperature pattern continues to show the southeast climate division as the hottest in 37 years and all but the northwestern climate division are above the 88th percentile.

 

Four-year period - The 48-month map continues to show much drier than average conditions everywhere except the northernmost and westernmost watersheds. Six of the eastern and central watersheds are below the 25th percentile. Temperatures in the southern climate divisions are above the 95th percentile, and the northern and western climate divisions are above the 77th percentile.