State Precipitation & Temperature Update for Arizona

Conditions through February 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 03/26/2008. The Upper Colorado and Santa Cruz still have some missing data. The data are preliminary.


 

Precipitation Percentiles by Watershed (through February 2008)

 

Temperature Percentiles by Climate Division (through February 2008)


SHORT TERM CONDITIONS: 1-6 MONTHS

February precipitation was near average for the southern half of the state, with slightly below-average precipitation in the southeast (Whitewater Draw and Willcox) and southwest (lower Colorado). The northern half of the state received well above-average precipitation for the month. The regular cycle of storms brought seasonable temperatures to the state, with all climate divisions reporting temperatures between the 45th and 58th percentiles. The three-month winter period of December through February has been very wet across most of the state, averaging between the 81st and 95th percentile. Cold, winter storms have moved through the state from the southwest to the northeast, throughout the winter. The driest watersheds are in the southeast, but they are between the 61st and 73rd percentile for precipitation, certainly wetter than average. The relatively cold weather in January and seasonal temperatures of February dropped the 3-month temperatures to near or below average. The 6-month period precipitation, from September through February, continues to remain near- or slightly below-average in the southeast, with Willcox and Whitewater Draw around the 35th percentile. The colder than average winter temperatures in the north have brought the three northern climate divisions below the 67th percentile, while the southeast remains above the 85th percentile for temperature.

Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

57.89

CD1

46.49

Upper Colorado

81.58

CD2

51.75

Little Colorado

78.95

CD3

45.61

Verde

65.79

CD4

50.44

Bill Williams

50.00

CD5

54.82

Agua Fria

57.89

CD6

55.26

Lower Gila

42.11

CD7

57.89

Salt

60.53

 

Lower Colorado

39.47

 

Upper Gila

42.11

 

Santa Cruz

52.63

 

San Pedro

42.11

 

Willcox Playa

29.73

 

San Simon

47.37

 

White Water Draw

31.58

 

FEBRUARY 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

83.33

CD1

41.67

Upper Colorado

91.89

CD2

29.82

Little Colorado

94.44

CD3

29.39

Verde

91.67

CD4

51.75

Bill Williams

81.08

CD5

41.23

Agua Fria

81.08

CD6

32.46

Lower Gila

81.08

CD7

39.47

Salt

89.19

 

Lower Colorado

72.97

 

Upper Gila

72.97

 

Santa Cruz

72.97

 

San Pedro

62.86

 

Willcox Playa

63.89

 

San Simon

81.08

 

White Water Draw

61.11

 

DECEMBER 2008 - FEBRUARY 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

44.12

CD1

66.67

Upper Colorado

83.78

CD2

63.16

Little Colorado

63.89

CD3

63.16

Verde

69.44

CD4

86.84

Bill Williams

56.76

CD5

70.18

Agua Fria

56.76

CD6

83.33

Lower Gila

67.57

CD7

87.72

Salt

81.08

 

Lower Colorado

45.95

 

Upper Gila

56.76

 

Santa Cruz

54.05

 

San Pedro

45.71

 

Willcox Playa

36.11

 

San Simon

72.97

 

White Water Draw

33.33

 

SEPTEMBER 2008 FEBRUARY 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 has again improved across all watersheds except the Upper Gila. Only the Virgin watershed is below average, below the 9th percentile. Temperatures remained high for all climate divisions, except the northwest, which finally dropped below the 85th percentile.

 

The 24-month period has seven watersheds below average, five watersheds near average, and three watersheds above average for precipitation. The drier watersheds are in the west and south central region, while the wetter than average watersheds are in the southeast. This is the opposite of the shorter-term precipitation conditions, which have the southeast as the driest region. The 24-month period picks up the past two monsoons which were very wet in the southeast. Temperatures for the 24-month period continue to be above the 86th percentile everywhere but the northwest, where they dropped just below the 79th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

8.57

CD1

80.53

Upper Colorado

81.08

CD2

92.04

Little Colorado

70.27

CD3

92.04

Verde

62.16

CD4

93.81

Bill Williams

51.35

CD5

92.92

Agua Fria

51.35

CD6

97.35

Lower Gila

83.78

CD7

98.23

Salt

70.27

 

Lower Colorado

62.16

 

Upper Gila

59.46

 

Santa Cruz

48.65

 

San Pedro

43.24

 

Willcox Playa

41.67

 

San Simon

67.57

 

White Water Draw

44.44

 

MARCH 2008 FEBRUARY 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

20.59

CD1

78.57

Upper Colorado

61.11

CD2

86.61

Little Colorado

63.89

CD3

88.39

Verde

47.22

CD4

86.61

Bill Williams

16.67

CD5

90.18

Agua Fria

31.94

CD6

93.75

Lower Gila

66.67

CD7

97.32

Salt

58.33

 

Lower Colorado

36.11

 

Upper Gila

63.89

 

Santa Cruz

41.67

 

San Pedro

50.00

 

Willcox Playa

61.11

 

San Simon

41.67

 

White Water Draw

63.89

 

MARCH 2007 FEBRUARY 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 is again the driest period with all watersheds below the 38th percentile. Five watersheds are below the 15th percentile and eight are between the 25th and 38th percentiles. Bill Williams and Agua Fria in west central Arizona, the San Simon, Santa Cruz, and San Pedro in the south remain extremely dry in the long-term, and the upper Gila has now fallen below the 15th percentile. Temperatures over the three-year period are above the 87th percentile in all climate divisions except the northwest, which he fallen below the 75th percentile.

 

The 48-month period is still split with above-average precipitation in the western watersheds, below-average precipitation in the southeastern watersheds, and near- average precipitation in the central and eastern watersheds. Santa Cruz, San Pedro and San Simon continue to be the driest long-term watersheds, while the upper and lower Colorado are the wisest watersheds. Climate division 7 in the southeast has had the hottest 4-year period since 1895, and only the northwest climate division of Mohave County remains below the 90th percentile.


Watershed

Precipitation Percentile

Climate Division

Temperature Percentile

Virgin

27.27

CD1

74.77

Upper Colorado

34.29

CD2

87.84

Little Colorado

37.14

CD3

90.99

Verde

17.14

CD4

94.59

Bill Williams

5.71

CD5

87.39

Agua Fria

5.71

CD6

95.50

Lower Gila

31.43

CD7

99.10

Salt

25.71

 

Lower Colorado

34.29

 

Upper Gila

14.29

 

Santa Cruz

11.43

 

San Pedro

20.00

 

Willcox Playa

31.43

 

San Simon

5.71

 

White Water Draw

34.29

 

MARCH 2006 FEBRUARY 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

58.06

CD1

76.36

Upper Colorado

76.47

CD2

90.00

Little Colorado

44.12

CD3

92.73

Verde

58.82

CD4

95.45

Bill Williams

50.00

CD5

90.00

Agua Fria

52.94

CD6

94.55

Lower Gila

64.71

CD7

100.00

Salt

55.88

 

Lower Colorado

79.41

 

Upper Gila

44.12

 

Santa Cruz

11.76

 

San Pedro

23.53

 

Willcox Playa

44.12

 

San Simon

29.41

 

White Water Draw

50.00

 

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

 

March 2008 Arizona Drought Update based on precipitation data through February 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

February precipitation was near average for the southern half of the state, with slightly below-average precipitation in the southeast (Whitewater Draw and Willcox) and southwest (lower Colorado). The northern half of the state received well above-average precipitation for the month. The regular cycle of storms brought seasonable temperatures to the state, with all climate divisions reporting temperatures between the 45th and 58th percentiles.

 

The 3-month winter period of December through February has been very wet across most of the state, averaging between the 81st and 95th percentile. Cold, winter storms have moved through the state from the southwest to the northeast, throughout the winter. The driest watersheds are in the southeast, but they are between the 61st and 73rd percentile for precipitation, certainly wetter than average. The relatively cold weather in January and seasonal temperatures of February dropped the 3-month temperatures to near or below average.

 

The 6-month period precipitation, from September through February, continues to remain near- or slightly below-average in the southeast, with Willcox and Whitewater Draw around the 35th percentile. The colder than average winter temperatures in the north have brought the three northern climate divisions below the 67th percentile, while the southeast remains above the 85th percentile for temperature.

 

The 12-month period has again improved across all watersheds except the Upper Gila. Only the Virgin watershed is below average, below the 9th percentile. Temperatures remained high for all climate divisions, except the northwest, which finally dropped below the 85th percentile.

 

The 24-month period has seven watersheds below average, five watersheds near average, and three watersheds above average for precipitation. The drier watersheds are in the west and south central region, while the wetter than average watersheds are in the southeast. This is the opposite of the shorter-term precipitation conditions, which have the southeast as the driest region. The 24-month period picks up the past two monsoons which were very wet in the southeast. Temperatures for the 24-month period continue to be above the 86th percentile everywhere but the northwest, where they dropped just below the 79th percentile.

 

The 36-month period is again the driest period with all watersheds below the 38th percentile. Five watersheds are below the 15th percentile and eight are between the 25th and 38th percentiles. Bill Williams and Agua Fria in west central Arizona, the San Simon, Santa Cruz, and San Pedro in the south remain extremely dry in the long-term, and the upper Gila has now fallen below the 15th percentile. Temperatures over the three-year period are above the 87th percentile in all climate divisions except the northwest, which he fallen below the 75th percentile.

 

The 48-month period is still split with above-average precipitation in the western watersheds, below-average precipitation in the southeastern watersheds, and near- average precipitation in the central and eastern watersheds. Santa Cruz, San Pedro and San Simon continue to be the driest long-term watersheds, while the upper and lower Colorado are the wisest watersheds. Climate division 7 in the southeast has had the hottest 4-year period since 1895, and only the northwest climate division of Mohave County remains below the 90th percentile.