State Precipitation & Temperature Update for Arizona

Conditions through May 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 4528/2007. The data are preliminary, and some data are missing from the San Pedro watershed.


 

Precipitation Percentiles by Watershed (through May 2007)

 

Temperature Percentiles by Climate Division (through May 2007)


SHORT TERM CONDITIONS: 1-6 MONTHS

May is generally a dry month across Arizona, and this year was no exception for all but the Upper Gila and San Pedro watersheds. Most of the state had less than average precipitation. Temperatures across the state were above average, but not as far above average as in the past two months. Maximum temperatures have not been much above normal, but frequent cloudy conditions have kept minimum temperatures above average. Precipitation for the 3-month period of March through May was well below the 40th percentile for the northern half of the state because the shift to La Nia conditions resulted in relatively dry conditions in March and April. The lack of frontal storm systems also resulted in temperatures above the 88th percentile everywhere in the state. The 6-month precipitation map still shows the effects of the dry winter with only four watersheds in the southeast corner of the state above the 25th percentile. Temperatures were above average everywhere in the state for the 6-month period.

 

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

24.32

CD1

88.05

Upper Colorado

54.05

CD2

78.32

Little Colorado

56.76

CD3

89.38

Verde

32.43

CD4

96.46

Bill Williams

37.84

CD5

84.96

Agua Fria

43.24

CD6

91.15

Lower Gila

51.35

CD7

88.05

Salt

56.76

 

Lower Colorado

22.97

 

Upper Gila

67.57

 

Santa Cruz

37.84

 

San Pedro

40.54

 

Willcox Playa

70.27

 

San Simon

13.51

 

White Water Draw

59.46

 

MAY 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

16.22

CD1

93.81

Upper Colorado

27.03

CD2

92.92

Little Colorado

18.92

CD3

91.15

Verde

16.22

CD4

96.46

Bill Williams

10.81

CD5

88.50

Agua Fria

16.22

CD6

92.04

Lower Gila

45.95

CD7

92.04

Salt

18.92

 

Lower Colorado

44.59

 

Upper Gila

51.35

 

Santa Cruz

21.62

 

San Pedro

54.05

 

Willcox Playa

75.68

 

San Simon

37.84

 

White Water Draw

81.08

 

MARCH 2006 - MAY 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

17.14

CD1

84.07

Upper Colorado

22.22

CD2

75.22

Little Colorado

20.00

CD3

79.65

Verde

17.14

CD4

91.15

Bill Williams

11.11

CD5

76.11

Agua Fria

16.67

CD6

84.96

Lower Gila

19.44

CD7

72.57

Salt

25.00

 

Lower Colorado

16.67

 

Upper Gila

38.89

 

Santa Cruz

25.00

 

San Pedro

35.29

 

Willcox Playa

48.57

 

San Simon

19.44

 

White Water Draw

54.29

 

DECEMBER 2006 MAY 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

All watersheds except those in the southeast are well below average for the 12 month period. The San Pedro, Willcox Playa, and White Water Draw watersheds in the southeast have had above average precipitation both during the 2006 summer, and the 2007 winter. Temperatures are above the 78th percentile everywhere in the state.

The two-year period has consistently been the driest period with all watersheds receiving well below average precipitation, nine are below the 9th percentile and two are below the 3rd percentile. This indicates that the drought is experiencing a cyclic wet-dry regime where each phase seems to last 12 months. For temperature, again all divisions are above the 75th percentile, exacerbating the dry conditions. The southeast climate division continues to be at the 100th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

20.59

CD1

80.36

Upper Colorado

33.33

CD2

78.57

Little Colorado

30.56

CD3

86.61

Verde

19.44

CD4

87.50

Bill Williams

11.11

CD5

89.29

Agua Fria

25.00

CD6

88.39

Lower Gila

25.00

CD7

90.18

Salt

33.33

 

Lower Colorado

25.00

 

Upper Gila

58.33

 

Santa Cruz

41.67

 

San Pedro

69.44

 

Willcox Playa

74.29

 

San Simon

22.22

 

White Water Draw

68.57

 

JUNE 2006 MAY 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

75.68

Upper Colorado

8.57

CD2

87.39

Little Colorado

8.57

CD3

89.64

Verde

5.71

CD4

92.79

Bill Williams

2.86

CD5

88.29

Agua Fria

2.86

CD6

94.59

Lower Gila

8.57

CD7

100.00

Salt

5.71

 

Lower Colorado

28.57

 

Upper Gila

20.00

 

Santa Cruz

8.57

 

San Pedro

28.57

 

Willcox Playa

40.00

 

San Simon

5.71

 

White Water Draw

34.29

 

JUNE 2005 MAY 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 is well below average in the southeastern watersheds and above average for the northern and western watersheds. This period includes the wet winter of 2005. The 36-month-temperature pattern has been consistent for the past five updates, with Gila County and the southeast climate division still above the 95th percentile for temperature, and all others above the 77th percentile.

 

All watersheds except the upper and lower Colorado have had well below average precipitation in the 48 month period. The three south central southeast climate divisions remain above the 95th percentile for temperature, due to the three warm dry winters of 2004-2006, in this region.

 

 


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

81.25

CD1

74.55

Upper Colorado

61.76

CD2

89.09

Little Colorado

29.41

CD3

88.18

Verde

44.12

CD4

95.45

Bill Williams

41.18

CD5

89.09

Agua Fria

32.35

CD6

90.91

Lower Gila

47.06

CD7

99.09

Salt

38.24

 

Lower Colorado

73.53

 

Upper Gila

38.24

 

Santa Cruz

5.88

 

San Pedro

23.53

 

Willcox Playa

38.24

 

San Simon

8.82

 

White Water Draw

47.06

 

JUNE 2004 MAY 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

-99.99

CD1

77.98

Upper Colorado

51.52

CD2

89.91

Little Colorado

24.24

CD3

93.58

Verde

30.30

CD4

96.33

Bill Williams

30.30

CD5

89.91

Agua Fria

21.21

CD6

97.25

Lower Gila

39.39

CD7

100.00

Salt

27.27

 

Lower Colorado

66.67

 

Upper Gila

24.24

 

Santa Cruz

12.12

 

San Pedro

15.15

 

Willcox Playa

18.18

 

San Simon

21.21

 

White Water Draw

33.33

 

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

 

June 2007 Arizona Drought Update based on Precipitation (data through May 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

May is generally a dry month across Arizona, and this year was no exception for all but the Upper Gila and San Pedro watersheds. Most of the state had less than average precipitation. Temperatures across the state were above average, but not as far above average as in the past two months. Maximum temperatures have not been much above normal, but frequent cloudy conditions have kept minimum temperatures above average.

 

Three-month period Precipitation for the 3-month period of March through May was well below the 40th percentile for the northern half of the state because the shift to La Nia conditions resulted in relatively dry conditions in March and April. The lack of frontal storm systems also resulted in temperatures above the 88th percentile everywhere in the state.

 

Six-month period The 6-month precipitation map still shows the effects of the dry winter with only four watersheds in the southeast corner of the state above the 25th percentile. Temperatures were above average everywhere in the state for the 6-month period.

 

Twelve-month period All watersheds except those in the southeast are well below average for the 12 month period. The San Pedro, Willcox Playa, and White Water Draw watersheds in the southeast have had above average precipitation both during the 2006 summer, and the 2007 winter. Temperatures are above the 78th percentile everywhere in the state.

Two-year period - has consistently been the driest period with all watersheds receiving well below average precipitation, nine are below the 9th percentile and two are below the 3rd percentile. This indicates that the drought is experiencing a cyclic wet-dry regime where each phase seems to last 12 months. For temperature, again all divisions are above the 75th percentile, exacerbating the dry conditions. The southeast climate division continues to be at the 100th percentile.

 

Three-year period - The 36-month precipitation is well below average in the southeastern watersheds and above average for the northern and western watersheds. This period includes the wet winter of 2005. The 36-month-temperature pattern has been consistent for the past five updates, with Gila County and the southeast climate division still above the 95th percentile for temperature, and all others above the 77th percentile.

 

Four-year period - All watersheds except the upper and lower Colorado have had well below average precipitation in the 48 month period. The three south central southeast climate divisions remain above the 95th percentile for temperature, due to the three warm dry winters of 2004-2006, in this region.