State Precipitation & Temperature Update for Arizona

Conditions through April 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 05/14/2008.  Upper Colorado watershed is missing 1 station.  The data are preliminary.


 

Precipitation Percentiles by Watershed (through April 2008)

       

 

Temperature Percentiles by Climate Division (through April 2008)

       
SHORT TERM CONDITIONS: 1-6 MONTHS

April was extremely dry across the entire state.  Precipitation was below the 10th percentile for all watersheds except the lower Colorado, San Simon, and Santa Cruz.  Even the wettest watershed was only at the 19th percentile.  Just as in March, only one winter storm moved through the state during April.  And, for the second month in a row, temperatures were only slightly above average across most of the state.  The three-month winter period of February through April was also drier than average across the state, as most places haven’t had precipitation since mid-February.  The three month period saw temperatures slightly warmer than average across the entire state, significantly cooler than this period has been in previous years.  The 6-month period precipitation, from November through April, was near- to slightly above-average in most watersheds, ranging from the 47th to the 71st percentile.  The driest watershed was the Virgin, at the 36th percentile.  The storms tracked from the southwest to the northeast as they moved across the state, leaving the southeast and northwest corners of the state dry.  Temperatures were near average on the Colorado Plateau, and slightly warmer in the central and western parts of the state.  Gila and the southeastern counties were much warmer than average.  

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

5.26

CD1

67.54

Upper Colorado

7.89

CD2

48.25

Little Colorado

7.89

CD3

57.89

Verde

7.89

CD4

73.25

Bill Williams

6.58

CD5

60.09

Agua Fria

5.26

CD6

72.81

Lower Gila

9.21

CD7

67.54

Salt

7.89

 

Lower Colorado

19.74

 

Upper Gila

6.58

 

Santa Cruz

15.79

 

San Pedro

7.89

 

Willcox Playa

6.58

 

San Simon

10.53

 

White Water Draw

7.89

 

APRIL 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

21.05

CD1

67.11

Upper Colorado

31.58

CD2

52.63

Little Colorado

21.05

CD3

54.82

Verde

26.32

CD4

67.11

Bill Williams

21.05

CD5

68.86

Agua Fria

13.16

CD6

68.86

Lower Gila

13.16

CD7

65.35

Salt

15.79

 

Lower Colorado

18.42

 

Upper Gila

13.16

 

Santa Cruz

15.79

 

San Pedro

13.16

 

Willcox Playa

8.11

 

San Simon

21.05

 

White Water Draw

11.84

 

FEBRUARY 2008 - APRIL 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

35.71

CD1

61.40

Upper Colorado

70.27

CD2

57.02

Little Colorado

69.44

CD3

64.47

Verde

58.33

CD4

86.84

Bill Williams

54.05

CD5

71.05

Agua Fria

59.46

CD6

73.68

Lower Gila

70.27

CD7

81.14

Salt

67.57

 

Lower Colorado

48.65

 

Upper Gila

51.35

 

Santa Cruz

52.70

 

San Pedro

48.57

 

Willcox Playa

47.22

 

San Simon

72.97

 

White Water Draw

47.22

 

NOVEMBER 2008 – APRIL 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 had near- to above-average precipitation in 11 watersheds, and below-average precipitation in the Virgin, Santa Cruz, San Pedro and Willcox watersheds.  Temperatures were above the 75th percentile for all climate divisions, with the highest temperatures in the south.

 

The 24-month period was much drier than it was last month, with no watersheds above the 59th percentile.  Three watersheds are still at or below the 25th percentile, nine are between the 40th and 59th percentiles, while last month six watersheds were above the 60th percentile.  Temperatures for the 24-month period warmed above the 86th percentile everywhere but the northwest, where they dropped slightly to the 78th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

5.71

CD1

74.34

Upper Colorado

70.27

CD2

81.42

Little Colorado

67.57

CD3

85.84

Verde

56.76

CD4

92.04

Bill Williams

45.95

CD5

84.96

Agua Fria

48.65

CD6

91.15

Lower Gila

70.27

CD7

92.04

Salt

70.27

 

Lower Colorado

56.76

 

Upper Gila

45.95

 

Santa Cruz

37.84

 

San Pedro

32.43

 

Willcox Playa

33.33

 

San Simon

51.35

 

White Water Draw

38.89

 

MAY 2008 – APRIL 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

77.68

Upper Colorado

44.44

CD2

86.61

Little Colorado

47.22

CD3

91.07

Verde

27.78

CD4

90.18

Bill Williams

11.11

CD5

92.86

Agua Fria

22.22

CD6

93.75

Lower Gila

52.78

CD7

97.32

Salt

47.22

 

Lower Colorado

38.89

 

Upper Gila

47.22

 

Santa Cruz

36.11

 

San Pedro

44.44

 

Willcox Playa

58.33

 

San Simon

38.89

 

White Water Draw

55.56

 

MAY 2007 – APRIL 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 long-term period, especially in the eastern half of the state.  All watersheds remain below the 35th percentile, and nine watersheds are below the 15th percentile.  For temperature, the southeast climate divisions are above the 95th percentile and even the coolest climate division, in the northwest, is above the 75th percentile.

 

The 48-month period had very dry conditions in the southeast, near average conditions in central Arizona, and slightly wetter than average conditions in the northern and western watersheds.  The Santa Cruz and San Pedro watersheds are at the 9th and 12th percentiles, respectively, while the upper and lower Colorado watersheds are at the 68th and 76th percentiles, respectively.  Again, all climate divisions are above the 75th percentile for temperature.  The past four years have been much warmer than the average of the past 112 years.

 
Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

12.12

CD1

75.68

Upper Colorado

31.43

CD2

89.19

Little Colorado

14.29

CD3

90.99

Verde

11.43

CD4

94.59

Bill Williams

2.86

CD5

87.39

Agua Fria

5.71

CD6

97.30

Lower Gila

28.57

CD7

100.00

Salt

14.29

 

Lower Colorado

28.57

 

Upper Gila

11.43

 

Santa Cruz

8.57

 

San Pedro

20.00

 

Willcox Playa

31.43

 

San Simon

8.57

 

White Water Draw

34.29

 

MAY 2006 – APRIL 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

45.16

CD1

75.45

Upper Colorado

67.65

CD2

89.09

Little Colorado

35.29

CD3

88.18

Verde

55.88

CD4

94.55

Bill Williams

38.24

CD5

85.45

Agua Fria

35.29

CD6

93.64

Lower Gila

58.82

CD7

99.09

Salt

44.12

 

Lower Colorado

76.47

 

Upper Gila

32.35

 

Santa Cruz

8.82

 

San Pedro

11.76

 

Willcox Playa

35.29

 

San Simon

17.65

 

White Water Draw

38.24

 

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

 

May 2008 Arizona Drought Update based on precipitation data through April 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

April was extremely dry across the entire state.  Precipitation was below the 10th percentile for all watersheds except the lower Colorado, San Simon, and Santa Cruz.  Even the wettest watershed was only at the 19th percentile.  Just as in March, only one winter storm moved through the state during April.  And, for the second month in a row, temperatures were only slightly above average across most of the state.

 

The 3-month winter period of February through April was also drier than average across the state, as most places haven’t had precipitation since mid-February.  The three month period saw temperatures slightly warmer than average across the entire state, significantly cooler than this period has been in previous years.

 

The 6-month period precipitation, from November through April, was near- to slightly above-average in most watersheds, ranging from the 47th to the 71st percentile.  The driest watershed was the Virgin, at the 36th percentile.  The storms tracked from the southwest to the northeast as they moved across the state, leaving the southeast and northwest corners of the state dry.  Temperatures were near average on the Colorado Plateau, and slightly warmer in the central and western parts of the state.  Gila and the southeastern counties were much warmer than average.

 

The 12-month period had near- to above-average precipitation in 11 watersheds, and below-average precipitation in the Virgin, Santa Cruz, San Pedro and Willcox watersheds.  Temperatures were above the 75th percentile for all climate divisions, with the highest temperatures in the south.

 

The 24-month period was much drier than it was last month, with no watersheds above the 59th percentile.  Three watersheds are still at or below the 25th percentile, nine are between the 40th and 59th percentiles, while last month six watersheds were above the 60th percentile.  Temperatures for the 24-month period warmed above the 86th percentile everywhere but the northwest, where they dropped slightly to the 78th percentile.

 

The 36-month period continues to be the driest long-term period, especially in the eastern half of the state.  All watersheds remain below the 35th percentile, and nine watersheds are below the 15th percentile.  For temperature, the southeast climate divisions are above the 95th percentile and even the coolest climate division, in the northwest, is above the 75th percentile.

 

The 48-month period had very dry conditions in the southeast, near average conditions in central Arizona, and slightly wetter than average conditions in the northern and western watersheds.  The Santa Cruz and San Pedro watersheds are at the 9th and 12th percentiles, respectively, while the upper and lower Colorado watersheds are at the 68th and 76th percentiles, respectively.  Again, all climate divisions are above the 75th percentile for temperature.  The past four years have been much warmer than the average of the past 112 years.