arizona climate summarydaily maximum rainfall included 4.07” at apache junction on the 23rd,...

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Arizona Climate Summary October 2019

Summary of conditions for September 2019

September 2019 Temperature and Precipitation Summary September 1st – 17th: September began where August left off with high pressure over the Four Corners and showers in

the eastern and southeastern counties. The first week of the month had rainfall somewhere in the state each day. On the

first, Payson reported 0.64”, Cottonwood had 1.04” on the 2nd, Coronado National Monument had 0.09” on the 3rd,

Navajo National Monument had 0.05” on the 4th, Kingman reported 0.19” on the 5th, Nogales had 0.55” on the 6th,

Prescott had 0.85” on the 7th, Elgin had 0.78” on the 8th, Douglas had 2.00” on the 9th and Bisbee-Douglass Airport had

0.16” on the 10th. Only the southeast had heavy rainfall. By the 8th the high pressure had moved off to the east allowing

westerly flow to bring in drier air for most of the state. The southeast corner remained humid, but no rainfall was

reported in Arizona on the 11th or 12th of September as a weak low-pressure system crossed the state. During the first 8

days of September high temperatures in the southwest deserts remained in the 105 to 112oF range while the coldest

nighttime temperatures hovered in the mid-40s. Nighttime temperatures in the Phoenix area remained in the mid to

upper 80’s. The low-pressure system brought some relief with temperatures dropping to or below 100oF in the lower

deserts through the 11th. Monsoonal rainfall was localized to the southeastern corner of the state from the 13th through

the 17th. Nogales reported 0.50” on the 13th, Bisbee-Douglas had 0.13” on the 14th, and 0.54” on the 15th, and Douglas

had 0.25” on the 17th. By the 17th the high pressure had again moved back to the southeastern U.S. and a low-pressure

system was moving down the west coast with drier air and westerly flow. This was the transition from the monsoon

circulation back to the fall weather pattern. The meteorological monsoon ended on the 17th with a total of 0.43” of rain

at Phoenix Airport. This was the 2nd driest monsoon on record. The driest was 1924 with 0.35” of rain at the Phoenix

station. However, with the new NWS definition of a “seasonal” monsoon as beginning June 15 and ending September

30th, our seasonal monsoon total was 0.66” and this would be the 5th driest behind 1914 as 2nd driest with 0.51”, and 1932

and 1993 tied at 3rd driest with 0.61”. Monsoon rainfall for Tucson and Flagstaff had no significant ranking.

September 18th – 30th: The state was dry on the 18th and St. Johns had 0.01” on the 19th. The 20th and 21st were also

dry statewide. As the low-pressure system approached the state along the California coast, Hurricane Lorena approached

Arizona from the south up through the Gulf of California. By the afternoon of the 22nd, the moisture reached Arizona

and the low-pressure system became cut-off from the trough. Violent thunderstorms , heavy rainfall, hail, lightning and

several weak tornados occurred in southern and central Arizona on the 23rd through the 27th as the cut-off low remained

relatively stationary just south of Arizona. This storm system was not associated with the monsoon, but was a typical

fall storm that tapped into tropical moisture. Last year this same type of storm occurred the first three days of October.

Daily maximum rainfall included 4.07” at Apache Junction on the 23rd, 2.39” at Elgin on the 24th, 2.38” at Coronado

National Monument on the 25th, 0.67” at Cottonwood on the 26th and 0.35” at Picacho Peak on the 27th. Storm totals

included 1.61” at Bisbee-Douglas Airport, 1.36” at Davis-Monthan AFB, 1.53” at Mesa Falcon Field, 3.08” at Nogales

Airport, 0.82” at Deer Valley Airport, 0.23” at Phoenix Airport, 2.15” at Pioneer Airfield, 0.79” at Prescott Airport,

0.67” at Scottsdale Airport, 0.80” at St. Johns, 1.68” at Tucson Airport, 0.38” at Window Rock, 0.78” at Winslow, 0.53”

at Yuma, 1.06” at Bellemont, 1.48” at Carefree, 1.48” at Cottonwood, 2.17” at East Mesa, 1.64” at Payson, 1.41” at

Show Low, 0.60” at Springerville, and 0.62” at Williams. Numerous water rescues were performed and many motorists

were stranded in flooded freeway underpasses and flooded washes. The last 3 days of September were dry statewide as

westerly winds brought dry air and cooler temperatures.

**Note: The discrepancy between the Statewide Temperature and Precipitation values for Phoenix, Flagstaff and

Tucson and the daily values in their graphs are due to the reporting times. Statewide Temperature and Precipitation

values are taken at 5pm, while official daily records at the airports are taken from Midnight to Midnight. Dr. Nancy J. Selover, State Climatologist

http://azclimate.asu.edu 480-965-0580

Edited by Nancy J. Selover

© 2019 Arizona State Climate Office

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In This Issue: Overview of September, graphs of the September daily maximum and minimum temperatures,

precipitation, mean daily dew points for Flagstaff, Phoenix, and Tucson; September climate statistics, maps of mean

monthly maximum and minimum temperatures, precipitation, dew points, wind speeds for September monsoon rainfall

maps; short-term drought maps for the beginning and end of September 2019; Long-term Drought Map through

September and graphs of the mean September temperature and precipitation for the period of record for Tucson,

Phoenix, and Flagstaff, graphs of the cumulative precipitation for the calendar year for Flagstaff, Phoenix, and Tucson.

Data are preliminary and are from the National Weather Service Forecast Offices in Flagstaff, Phoenix and Tucson.

September 2019 Daily Temperature, Precipitation, & Dew Point for Flagstaff, Phoenix, and Tucson

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FLAGSTAFF CLIMATE STATISTICS

September 2019

This September had no significant ranking for

temperature or precipitation.

Avg Max Temp(F) 73.8 Normal 72.9

Avg Min Temp(F) 44.7 Normal 42.0

Avg Mean Temp(F) 59.3 Normal 57.4

Departure from Normal (F) +1.9

Highest Monthly Avg Temp (F) 62.1 in 1947

Lowest Monthly Avg Temp (F) 52.3 in 1912

Highest Temp this month (F): 89 on 1st

Lowest Temp this month (F): 28 on 22nd

Record High (F): 91 on 9/1,2,3/1948

Record Low (F): 20 on 9/22/1912

Temperature or precipitation records this month.

2nd HiMin 56 set, previous record 55 in 1936

7th HiMin 56 set, previous record 55 in 1903


Flagstaff Number of Days of:

Minimum Temp 50oF or higher 8

Minimum Temp 40oF or lower 7

Maximum Temp 85oF or higher 4

Maximum Temp 80oF or lower 9

Heating Degree Days 191 Normal 230

Cooling Degree Days 25 Normal 3

Degree base 65oF

Total September Precipitation 0.95”

Normal September Precipitation 2.38”

Departure from normal -1.43”

Greatest 24-Hr Precipitation 0.70” on 23rd

Total Precipitation Year-to-Date 17.25”

Departure from Normal +0.68”

Total September Snowfall 0.0” Normal Trace

Record September Snowfall 0.0”

Number of Days:

Clear 22

Partly Cloudy 8

Cloudy 0

Greatest September Precipitation 6.75” in 1983

Least September Precipitation: Trace in 1992,

1973, 1957, and 1955.

Average Wind Speed 8.3 mph

Highest Peak Gust 48 mph from 210o on 29th

PHOENIX CLIMATE STATISTICS

September 2019

This September was the 20th warmest and had no

significant ranking for precipitation.



Avg Mean Temp (F) 89.1 Normal 88.4




Highest Temp this month (F) 112 on 4th

Lowest Temp this month (F): 68 on 24th and 30th

Record High (F): 113 on 9/5/1945

Record Low (F): 47 on 9/20-21/1965, 9/22/1895

Temperature or precipitation records this month:

4th HiMax 112 tied, first set in 1948

6th HiMin 89 tied, first set in 2013


Phoenix Number of Days of:







Degree base 65oF



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Departure from normal -0.39”

Greatest 24-Hr Precipitation 0.17” on 23rd


Least September Precipitation 0.00” in 1968, 1973,

1988 and 13 other years.

Precipitation since January 1st 3.68”

Departure from Normal -2.24”

Number of Days:

Clear 13

Partly Cloudy 17

Cloudy 0


Highest Peak Gust 51 mph from 70o on 1st

TUCSON CLIMATE STATISTICS

September 2019

This September had no significant ranking for

temperature or precipitation.



Avg Mean Temp(F) 82.2 Normal 81.6




Highest Temp this month (F): 105 on 4th

Lowest Temp this month (F): 60 on 30th

Record High (F): 107 on 9/14/2000, 9/10-11/1990

Record Low (F): 43 on 9/26/1913

Temperature or precipitation records this month:



Tucson Number of Days of:







Degree base 65oF



Departure from normal +1.13”

Greatest 24-Hr Precipitation 0.66”on 24th

Total Precipitation Year-to-Date 10.67”

Departure from Normal +0.89”


Least September Precipitation 0.00” in 1953,

1973, 1968 and 3 other years

Number of Days:

Clear M

Partly Cloudy M

Cloudy M


Highest Peak Gust 43 mph from 280 on 16th

Data are from the National Weather Service and the

National Climatic Data Center and are preliminary.

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Wind Speeds for September:

Day Phoenix Flagstaff Tucson

(mph) Avg Max Avg Max Avg Max

1 8.1 51 7.3 26 8.4 31

2 7.1 20 3.4 23 5.8 26

3 7.7 23 3 26 6.4 28

4 7.9 24 4.4 29 8.6 31

5 6.4 22 4.2 22 7.3 21

6 8.8 21 4.7 25 6.1 23

7 9.3 27 5.8 23 9.8 36

8 8.2 29 12.1 39 8.3 24

9 7.8 24 8.6 30 6.4 35

10 10.7 29 15.1 42 11.3 31

11 5.8 19 13 35 6.8 28

12 4.5 17 6.1 24 5.1 19

13 4 25 2.6 19 7.5 28

14 9.8 43 4.3 18 16 36

15 5.1 17 5.2 24 7.9 27

16 9.3 41 8 32 8.7 43

17 5.6 19 11.5 40 6.5 25

18 5.7 20 9.9 40 6.5 18

19 8.9 24 13.3 43 6.9 27

20 6.5 26 13.3 39 8.1 31

21 5.6 19 6.2 31 4.9 17

22 5.3 17 4.2 26 4.7 39

23 11.9 41 3.8 26 6.6 40

24 7.3 25 6.9 26 8.6 40

25 6.1 31 3.2 21 10 33

26 6.6 36 6 26 6.4 31

27 5.2 21 6.6 24 3.5 15

28 7.3 21 15.1 39 5.8 15

29 6.4 20 25.9 48 8.3 26

30 4.3 24 14 39 3.6 17

Dew Points for September:

Daily Average Dew Point (oF):

Day Flg Phx Tuc

1 62 60 47

2 61 61 45

3 58 57 45

4 57 55 46

5 60 57 45

6 59 58 42

7 61 61 46

8 60 61 41

9 64 60 49

10 59 58 42

11 53 56 33

12 43 47 27

13 51 50 31

14 54 59 38

15 60 59 46

16 59 57 45

17 58 55 44

18 51 49 36

19 40 45 29

20 36 50 21

21 33 52 18

22 61 58 35

23 57 61 39

24 62 61 43

25 64 59 46

26 63 60 45

27 63 58 49

28 59 52 46

29 50 49 37

30 48 45 41

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The

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September 2019

The minimum temperatures ranged from 23oF at Sunset Crater, Flagstaff and Bellemont to 68oF at Phoenix Airport. The lowest maximum temperature of

72oF was recorded at Snowslide Canyon and the highest was 116oF at Havasu and Laughlin-Bullhead City. The highest rainfall totals were 6.21” at Mayer,

6.22” at Douglas, and 7.44” at Benson. The lowest average dew point was 35oF at Page and the highest was 61oF at Sahuarito. The highest peak wind gust

was 58 mph at Parker. Average wind speeds ranged from 2 mph at San Simon to 12 mph at Kingman, Show Low and Flagstaff.

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T

September 2019

The lowest average minimum temperature was 40oF at Grand Canyon and Bellemont and the highest was 79oF at Phoenix. The highest average maximum

temperature was 103oF at Tacna, Havasu, Yuma and Litchfield Park and the lowest average maximum temperature was 63oF at Snowslide Canyon and

Columbine.

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Short-term Drought

The monsoon rainfall in September fell primarily in southeastern Arizona. A late September storm system brought heavy rainfall to southwestern and central

Arizona leaving the area near the Yuma, Pima and Maricopa County boundary without drought and eastern Yavapai County Abnormally Dry (D0). The

month was relatively dry in many locations, leading to worsening of drought conditions. The area in No Drought was reduced from 24% of the state to just

5% in southeastern and southwestern Arizona. Severe Drought (D2) increased from 0% to 25% during the month. Much of the state that was Abnormally

Dry (D0) is now in Moderate Drought (D1).

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The long-term drought map for September shows hydrologic drought, based on precipitation and evaporation

using the Standardized Precipitation Evaporative Index (SPEI) and the Standardized Precipitation Index (SPI)

over the past 24-, 36-, and 48-months. This depiction is for water resources, not short-term drought (rangeland

conditions). While there had been some improvement in the long-term conditions due to the extremely wet

winter and some precipitation into the spring, September was a continuation of the dry July and August, so there

has been some degradation in long-term drought, particularly in the northern 2/3 of the state. Cochise, western

Maricopa and eastern Yavapai counties had above average monsoon rainfall and saw little degradation in long-

term drought.

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Monsoon 2019 Precipitation

Most of the state received below average precipitation for the monsoon. Northern Arizona and south-central

Arizona were especially dry. The extreme above average rainfall percentage in northern Apache County NE of

Kayenta is a bad data point. Western Maricopa County and much of Cochise County had above average

monsoon rainfall, but storms were very localized, and few of them brought heavy rain. The exception was the

last week of September when tropical moisture from the remnants of Hurricane Lorena moved into Arizona and

combined with a cut-off low pressure system. This was technically not a monsoon storm, but was part of the

transition from the monsoon circulation back to the westerly flow of the fall.

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September 2019

Minimum temperatures were 1-4oF warmer than average across most of the state. The western 2/3 of Pima County was cooler than average due to several rain

events. Maximum temperatures were 2-4oF warmer than average across northern Arizona and within 2oF of average across most of the state. The September

precipitation map shows that much of northwestern and north central Arizona had less than 25% of average rainfall while most of the southern half of the state

had over 150% of average. Western Pinal County had less than 100% of average as did Greenlee and western La Paz counties.

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Calendar Year 2019

Minimum temperatures were within 2oF of average across the entire state, with the warmer than average area primarily in northeastern Arizona, and cooler

conditions in southern and northwestern Arizona. Daytime temperatures were 0 to 3oF cooler than average statewide with northern Coconino, Navajo and

Apache and southern Pima counties warmer than average. Precipitation since January 1st has ranged from less than 70% of average in eastern Arizona and

western Yuma and La Paz counties to well over 150% of average in Mohave, southwestern Maricopa and western Pima counties.

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2019 Water Year

The Water Year ended with minimum temperatures within 1oF of average across most of the state. The northwest, east central and southern counties were

slightly cooler than average while the northeast plateau was slightly warmer than average. Daytime temperatures were 0-3oF cooler than average across the

entire state with the coolest conditions in eastern Gila, southern Navajo and Apache counties and northwestern Maricopa County. This was largely due to the

cold wet winter. Precipitation has been 100-130% of average across most of the state with the exception of Graham, Greenlee, northern Cochise, far western

Yuma and La Paz, and parts of Apache County. The southeast part of the state was left out of much of the winter storms, and the monsoon did not

significantly improve conditions in Graham, Greenlee or eastern Cochise County.

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September Mean Temperature Graphs – Flagstaff, Phoenix, and Tucson 1895-2019:

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September Precipitation Graphs – Flagstaff, Phoenix, and Tucson 1895-2019

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2019 Cumulative Precipitation Graphs – Flagstaff, Phoenix and Tucson:

Flagstaff is 1.43” below normal, Phoenix is 2.24” below normal, and Tucson was 0.89” above normal.

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The downloadable normals and extremes calendars use the following abbreviations:

NORM = 30 year (1971-2000) average value (degrees Fahrenheit (F))

OBS = The temperature observation for that day this year

AVG = Average daily temperature

HI MAX = Highest maximum temperature for that day (F)

LO MAX = Lowest maximum temperature for that day (F)

LO MIN = Lowest minimum temperature for that day (F)

HI MIN = Highest minimum temperature for that day (F)

Mx PCP = Maximum precipitation for that day (inches)

Mx SNO = Maximum snowfall for that day (inches)

arizona climate summarydaily maximum rainfall included 4.07” at apache junction on the 23rd,...

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