State Precipitation & Temperature Update for Arizona

Conditions through June 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 7/25/2007.  The data are preliminary.


 

Precipitation Percentiles by Watershed (through June 2007)

 

Temperature Percentiles by Climate Division (through June 2007)


SHORT TERM CONDITIONS: 1-6 MONTHS

June is generally a dry month across Arizona, and this year was no exception for most of the state, except the southeast corner which received above-average rainfall due to moisture moving southwest from New Mexico.  New Mexico has had a very rainy month.  Temperatures across the state were well above average, with Gila county temperatures in the 95th percentile.  For the 3-month period of April through June, precipitation was well below average, as there was little moisture for the spring frontal systems to work on.  The dry conditions contributed to higher temperatures during the three month period with all climate divisions above the 79th percentile.  The 6-month precipitation map reflects the dry winter and spring with only the southeastern watersheds above the 28th percentile.  Temperatures were below the 85th percentile in the north and west, and above the 88th percentile in the central and southeastern climate divisions.

 

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

13.89

CD1

83.19

Upper Colorado

2.70

CD2

86.73

Little Colorado

37.84

CD3

86.28

Verde

13.51

CD4

95.58

Bill Williams

17.57

CD5

69.91

Agua Fria

18.92

CD6

88.05

Lower Gila

48.65

CD7

89.38

Salt

35.14

 

Lower Colorado

29.73

 

Upper Gila

72.97

 

Santa Cruz

24.32

 

San Pedro

81.08

 

Willcox Playa

60.81

 

San Simon

51.35

 

White Water Draw

67.57

 

JUNE 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

22.22

CD1

86.28

Upper Colorado

32.43

CD2

88.50

Little Colorado

21.62

CD3

92.04

Verde

8.11

CD4

98.23

Bill Williams

10.81

CD5

79.65

Agua Fria

13.51

CD6

86.73

Lower Gila

35.14

CD7

87.17

Salt

24.32

 

Lower Colorado

32.43

 

Upper Gila

51.35

 

Santa Cruz

21.62

 

San Pedro

40.54

 

Willcox Playa

59.46

 

San Simon

29.73

 

White Water Draw

59.46

 

APRIL 2006 - JUNE 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

14.29

CD1

84.07

Upper Colorado

18.92

CD2

84.07

Little Colorado

22.22

CD3

88.50

Verde

16.22

CD4

93.81

Bill Williams

8.11

CD5

78.76

Agua Fria

18.92

CD6

89.38

Lower Gila

27.03

CD7

91.15

Salt

21.62

 

Lower Colorado

18.92

 

Upper Gila

45.95

 

Santa Cruz

18.92

 

San Pedro

43.24

 

Willcox Playa

52.78

 

San Simon

18.92

 

White Water Draw

66.67

 

JANUARY 2006 – JUNE 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 both the past winter and last year’s monsoon.  For all areas of the state except the southeast, the entire 12 month period was exceptionally dry.  The southeast watersheds received above-average rainfall during the 2006 monsoon season, bringing flooding to many locations, including Tucson.  The extreme dryness is reflected in the higher than average temperatures.  Temperatures are above the 79th percentile everywhere in the state.

 

The two-year period precipitation is evidence of our two consecutive years of extreme dryness.  The only watersheds above the 29th percentile are Willcox Playa and White Water Draw, which received much needed rainfall during the 2006 monsoon.  The entire state was very warm during the past 24 months, with the southeast and south central climate divisions having average temperatures above the 96th percentile. 

 


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

17.65

CD1

79.46

Upper Colorado

30.56

CD2

79.46

Little Colorado

27.78

CD3

82.14

Verde

13.89

CD4

85.27

Bill Williams

8.33

CD5

83.48

Agua Fria

22.22

CD6

87.50

Lower Gila

22.22

CD7

86.61

Salt

27.78

 

Lower Colorado

25.00

 

Upper Gila

58.33

 

Santa Cruz

36.11

 

San Pedro

66.67

 

Willcox Playa

80.00

 

San Simon

19.44

 

White Water Draw

71.43

 

JULY 2006 – JUNE 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

21.21

CD1

76.58

Upper Colorado

5.71

CD2

90.99

Little Colorado

11.43

CD3

90.09

Verde

2.86

CD4

91.89

Bill Williams

2.86

CD5

90.99

Agua Fria

2.86

CD6

96.40

Lower Gila

8.57

CD7

100.00

Salt

5.71

 

Lower Colorado

28.57

 

Upper Gila

17.14

 

Santa Cruz

8.57

 

San Pedro

25.71

 

Willcox Playa

42.86

 

San Simon

5.71

 

White Water Draw

45.71

 

JULY 2005 – JUNE 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 includes the wet winter of 2004-2005 for northern Arizona, and the dry monsoon for the southeast.  The pattern is very different from the 24-month period, due to the wet 2004-2005 winter.  Even though drought is occasionally punctuated by a wet year, the winter of 2004-2005 was not predicted, but was certainly welcome in many parts of the state.  The 36-month-temperature pattern has become hotter as all watersheds are now above the 74th percentile, and six of the seven watersheds are above the 86th percentile.

 

The 48-month map shows that three of the past 4 years have been extremely dry throughout most of Arizona, with only the Virgin and Lower Colorado River watersheds above the 51st percentile.  Most of the eastern watersheds are below the 24th percentile.  Again, the 4-year dry period is accompanied by temperatures well above average across the state, with the southeast climate divisions above the 96th percentile.  The combination of high temperatures and dry conditions increases the evaporative demand for moisture, drying out the soil and stressing the vegetation.

 


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

81.25

CD1

74.55

Upper Colorado

61.76

CD2

88.18

Little Colorado

32.35

CD3

88.18

Verde

47.06

CD4

94.55

Bill Williams

41.18

CD5

86.36

Agua Fria

32.35

CD6

93.64

Lower Gila

50.00

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

 

JULY 2004 – JUNE 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

77.06

Upper Colorado

51.52

CD2

91.74

Little Colorado

21.21

CD3

94.50

Verde

27.27

CD4

96.33

Bill Williams

30.30

CD5

89.91

Agua Fria

21.21

CD6

98.17

Lower Gila

42.42

CD7

100.00

Salt

24.24

 

Lower Colorado

66.67

 

Upper Gila

24.24

 

Santa Cruz

12.12

 

San Pedro

18.18

 

Willcox Playa

21.21

 

San Simon

21.21

 

White Water Draw

36.36

 

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

 

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

June 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 April through June was well below the 40th percentile for the northern half of the state because the shift to La Niρa conditions resulted in relatively dry conditions in April and May.  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.