Arizona Climate Summary September 2017 Summary of conditions for August 2017

August 2017 Temperature and Precipitation Summary Arizona Climate Summary September 2017 Summary of conditions for August 2017 August 1 st 15 th : The monsoon activity that ended July continued into the first week of August before a drying trend began across the state. Moisture was drawn into the state from the southeast. On the 1 st, Safford had 1.37 of rain while Yuma had 0.71, Bisbee had 0.47 and Coronado National Monument had 0.60. The system moved to the northwest bringing 0.79 to Williams, 0.60 to the Grand Canyon North Rim, 0.69 to the Grand Canyon South Rim, and 0.59 to Prescott on the 2 nd. On the afternoon and evening of the 3 rd, Phoenix Airport had 0.92 while other locations in the valley had as much as 2.28 causing widespread street flooding and extensive damage to the Phoenix Zoo. East Mesa also had over an inch of rain as the activity moved to central Arizona. By the 5 th the center of activity moved back to northern Arizona with Williams receiving 1.12 on the 5 th, and 0.41 on the 6 th and 7 th. Temperatures remained slightly warmer than average this first week, until the 8 th when high pressure moved back over the southern border bringing drier air to Arizona and much higher temperatures to the southwest and central deserts through the 11 th. Rainfall on the 9 th and 10 th was light and fell mostly in southern Arizona, though Flagstaff had 0.14 and Springerville had 0.05. By the 11 th the high pressure ridge was over western Texas and pumped moisture northward from Mexico into the state, bringing another round of thunderstorms, with the highest rainfall totals in northern and northeastern Arizona. On the 11 th, Bellemont had 0.82, and on the 12 th Springerville had 0.60. Storms moved across the entire state on the 13 th dropping 2.50 of rain on Castle Hot Springs, just northwest of Phoenix, 1.48 at Tucson, 2.13 at the north rim of the Grand Canyon, 0.78 at Sonora Desert Museum, 1.07 at Bisbee-Douglas, 2.04 at Davis Monthan AFB, 0.46 at Nogales, 2.13 at Eloy, 0.36 at Sky Harbor, and 0.80 at Cottonwood. By the 14 th the high pressure was retreating down into Mexico and a low pressure trough developed across the western state, suppressing the moisture a bit and restricting storms to the higher elevations and the southern counties. On the 14 th Show Low had 0.53 and on the 15 th Coronado National Monument had 0.24. August 16 th 31 st : On the 16 th, 17 th, and 18 th, the monsoon took a short break. On the 19 th the high pressure had redeveloped over Arizona and began to draw moisture in from the southeast. Bisbee-Douglas had 0.11 of rain on the 19 th and on the 20 th showers were still light but more widespread with 0.30 at Springerville and 0.19 at Flagstaff. By the 21 st more moisture moved in and Williams received 1.20 of rainfall. Seligman had 0.23 and Yuma had 0.83, with 0.28 at Window Rock and 0.59 at the south rim of the Grand Canyon. On the 22 nd the north rim of the Grand Canyon had 0.17, but heavier rain returned on the 23 rd and 24 th with 1.14 at Sonora Desert Museum, and 1.02 at Cottonwood. Drier conditions prevailed on the 25 th and 26 th with only 0.13 at Show Low on the 25 th and 0.03 at Safford on the 26 th. The drier conditions brought higher temperatures to the state with central and western Arizona reaching above 110 o F from the26th through the end of the month. Central Arizona was hit by thunderstorms on the 27 th with Apache Junction receiving 0.63. Bullhead City got 0.25 on the 27 th. Show Low had 0.44 on the 28 th, with 0.27 at Flagstaff on the 29 th, 0.29 at Williams on the 30 th, and 0.02 at the Grand Canyon south rim on the 31 st. Temperatures remained above 110 o F at the hottest southwest desert locations through the end of the month. Overall this August was fairly typical of the monsoon with mostly wet days statewide, though thunderstorms were quite scattered and localized, and the southwest deserts have had long dry periods between the rain days. In This Issue: Overview of August, graphs of the August daily maximum and minimum temperatures, precipitation, mean daily dew points for Flagstaff, Phoenix, and Tucson; August climate statistics, maps of mean monthly maximum and minimum temperatures, precipitation, dew points, wind speeds for August; and graphs of the mean August 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. Climate calendars for Flagstaff, Phoenix, Tucson, Prescott, Winslow and Yuma, including daily and monthly normals and extremes, for each month of the year, are not yet 1

updated through 2017. See p.19 of this report for calendar abbreviations. Data are preliminary and are from the National Weather Service Forecast Offices in Flagstaff, Phoenix and Tucson. **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 2017 Arizona State Climate Office August 2017 Daily Temperature, Precipitation, & Dew Point for Flagstaff, Phoenix, and Tucson 2

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FLAGSTAFF CLIMATE STATISTICS August 2017 This August had no significant ranking for temperature or precipitation. Avg Max Temp (F) 77.8 Normal 78.4 Avg Min Temp (F) 49.6 Normal 50.1 Avg Mean Temp (F) 63.7 Normal 64.2 Departure from Normal (F) --0.5 Highest Monthly Avg Temp (F) 67.5 in 1944 Lowest Monthly Avg Temp (F) 59.5 in 1968 Highest Temp this month (F): 86 on 27 th Lowest Temp this month (F): 38 on 16 th Record High (F): 93 on 8/02/1902 Record Low (F): 32 on 8/23/1968 No temperature or precipitation records this month: Flagstaff Number of Days of: Minimum Temp 55 o F or higher 3 Minimum Temp 50 o F or lower 19 Maximum Temp 80 o F or higher 13 Maximum Temp 75 o F or lower 7 Heating Degree Days 48 Normal 56 Cooling Degree Days 16 Normal 33 Degree base 65 o F Total August Precipitation 3.29 Normal August Precipitation 3.11 Departure from normal +0.18 Greatest 24-Hr Precipitation 1.05 on 4 th Total Precipitation Year-to-Date 17.58 Departure from Normal +3.39 Total August Snowfall 0.0 Normal 0.0 Record August Snowfall 0.0 Number of Days: Clear 23 Partly Cloudy 8 Cloudy 0 Greatest August Precipitation 8.77 in 1904 Least August Precipitation: 0.26 in 1962 Average Wind Speed Highest Peak Gust 4.2 mph 33 mph from 230 o on 14 th PHOENIX CLIMATE STATISTICS August 2017 This August had no significant ranking for temperature or precipitation. Avg Max Temp(F) 105.4 Normal 104.4 Avg Min Temp(F) 82.6 Normal 82.7 Avg Mean Temp (F) 94.0 Normal 93.6 Departure from Normal (F) +0.4 Highest Monthly Avg Temp (F) 98.3 in 2011 Lowest Monthly Avg Temp (F) 84.6 in 1918 Highest Temp this month (F) 111 on 9 th & 27 th Lowest Temp this month (F): 73 on 13 th Record High (F): 117 on 8/14/2015, 8/26/2011 Record Low (F): 58 on 8/20/1917 Temperature or precipitation records this month: 13 th Precip 0.33 set, previous record 0.28 in 2009 28 th HiMin 90 set, previous record 89 in 2011 5 Phoenix Number of Days of: Minimum Temp 80 o F or lower 9 Minimum Temp 90 o F or higher 1 Maximum Temp 100 o F or lower 2 Maximum Temp 110 o F or higher 4 Heating Degree Days 0 Normal 0 Cooling Degree Days 907 Normal 885 Degree base 65 o F Total August Precipitation 1.43 Normal August Precipitation 1.00 Departure from normal +0.43 Greatest 24-Hr Precipitation 0.92 Total Precipitation Year-to-Date 4.73 Departure from Normal -0.55 Greatest August Precipitation 5.33 in 1951 Least August Precipitation 0.00 in 1973 and 1975.

Number of Days: Clear 13 Partly Cloudy 18 Cloudy 0 Average Wind Speed 6.7 mph Highest Peak Gust 48 mph from 050 o on 3 rd TUCSON CLIMATE STATISTICS August 2017 This August was tied for 8 th warmest with 1995 and had no significant ranking precipitation. Avg Max Temp(F) 99.5 Normal 97.4 Avg Min Temp(F) 75.1 Normal 73.3 Avg Mean Temp(F) 87.3 Normal 85.3 Departure from Normal (F) +2.0 Highest Monthly Avg Temp (F) 90.2 in 1994 Lowest Monthly Avg Temp (F) 80.8 in 1923 Highest Temp this month (F): 106 on 9 th Lowest Temp this month (F): 68 on 13 th, 16 th Record High (F): 112 on 8/1/1993 Record Low (F): 55 on 8/20/1917 Temperature or precipitation records this month: 12 th HiMin 81 tied, first set in 2003 30 th HiMin 81 set, previous record 80 in 2007 Tucson Number of Days of: Minimum Temp 70 o F or lower 2 Minimum Temp 80 o F or higher 2 Maximum Temp 95 o F or lower 3 Maximum Temp 105 o F or higher 1 Heating Degree Days 0 Normal 0 Cooling Degree Days 652 Normal 631 Degree base 65 o F Total August Precipitation 1.74 Normal August Precipitation 2.39 Departure from normal -0.65 Greatest 24-Hr Precipitation 1.48 on 13 th Total Precipitation Year-to-Date 10.15 Departure from Normal +2.24 Greatest August Precipitation 7.93 in 1955 Least August Precipitation: 0.08 in 1924. Number of Days: Clear 15 Partly Cloudy 1 Cloudy 0 Average Wind Speed Highest Peak Gust 7.4 mph 44 mph from 130 o on 2 nd Data are from the National Weather Service and the National Climatic Data Center and are preliminary. 6

Wind Speeds for August: Day Phoenix Flagstaff Tucson (mph) Avg Max Avg Max Avg Max 1 9.8 29 7.5 27 8.1 32 2 8.9 24 3.5 25 8.3 44 3 6.6 48 4.7 24 7.7 41 4 5.1 21 3 23 5.8 26 5 6.4 19 4.7 29 5.6 18 6 6 32 4.4 15 4.7 39 7 5.8 21 4.3 25 5.2 26 8 5.1 23 4.5 22 5.8 18 9 5.5 17 3.8 25 8.6 39 10 7 37 3.8 23 M M 11 6.3 23 2.9 16 M M 12 7.6 31 4.6 32 M M 13 6.8 23 5.9 27 M M 14 8.1 21 8.2 33 8.1 37 15 4.5 21 7.3 29 10 27 16 7.2 27 4.5 23 6.4 15 17 5.8 17 4.1 20 4.3 18 18 4.3 20 3.9 23 M M 19 5.9 20 5.3 23 M M 20 7 17 4.4 21 5.5 15 21 7.5 20 2.1 18 6 16 22 5.2 15 2.4 20 M 31 23 9.2 42 4.2 22 6.2 40 24 5.7 20 3.7 22 7.2 28 25 5 22 2 16 6.9 26 26 6.4 38 3.3 22 9.3 39 27 7.2 28 3.8 27 7.8 26 28 8.4 34 3.7 30 10 31 29 5.7 18 3.4 30 9.7 28 30 7 22 3.5 21 12.3 28 31 7.6 28 3.5 25 9.8 34 Dew Points for August: Daily Average Dew Point ( o F): Day Phx Tuc Flg 1 66 65 54 2 67 66 54 3 68 65 55 4 65 62 54 5 56 60 54 6 51 55 50 7 48 53 45 8 45 55 41 9 54 60 47 10 60 63 52 11 64 64 54 12 66 64 55 13 64 61 54 14 56 60 43 15 46 46 37 16 40 46 36 17 40 44 37 18 44 47 36 19 50 55 45 20 53 52 48 21 52 55 48 22 55 58 46 23 57 58 49 24 58 59 47 25 55 56 46 26 55 57 45 27 52 53 45 28 52 50 45 29 52 48 46 30 45 40 48 31 51 39 47 7

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The minimum temperatures ranged from 25 o F at Sunset Crater to 83 o F at Yuma. The lowest maximum temperature of 71 o F was recorded at Snowslide Canyon, while the highest maximum temperature was 117 o F at Tacna, Ehrenburg, Bullhead City and Havasu. Several locations had no rainfall, while the highest rainfall amounts were 6.04 at Oracle State Park and 5.59 at Hereford 1.1 WSW. The lowest average dew point was 44 o F at Window Rock and Page and the highest was 64 o F at Coolidge. The highest peak wind gust was 53 mph at Paloma. Average wind speeds ranged from 2 mph in Payson to 11 mph at Kingman. 9

T August 2017 The highest average minimum temperature was 86 o F at Laughlin-Bullhead City, and the lowest average minimum temperature was 41 o F at Sunset Crater and Sunrise Mountain. The highest average maximum temperature was 111 o F at Havasu and the lowest average maximum temperature was 66 o F at Snowslide Canyon. 10

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August August minimum temperatures were within 2 degrees of normal, though central Gila County was much warmer due to the lack of monsoon activity this month, and the intersection of Gila, Yavapai and Coconino counties was much cooler than normal. Much of Yuma, western La Paz and western Pima counties were 2-4 o F warmer than normal. Daytime temperatures were within 1 o F of normal across much of northern Arizona, with some cooler than normal areas in central Coconino and southern Navajo counties. Southern and west central Arizona were 1-3 o F warmer than normal. Much of the state received less than 70% of normal August precipitation. Central Coconino, southern and eastern Maricopa and western Pinal counties were wetter than normal 12

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Calendar Year 2017 Nighttime temperatures were 0 to 3 o F warmer than average across the state with cooler than normal pockets in La Paz, Cochise, Graham, southern Navajo and western Pima counties. Daytime temperatures were 0 to 4 o F warmer than normal across most of the state with slightly cooler than normal pockets in western Pima, southern Navajo, northwestern Maricopa, and southern Mohave counties. The northern 2/3 of the state has been wetter than normal with the exception of southern Mohave County. There is also a dry pocket in La Paz and Yuma counties and central Navajo County. 14

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2017 Water Year The 2017 Water Year nighttime temperatures have been 0 to 4 o F warmer than average across most of the state. La Paz, southern Graham, northern Cochise, and western Pima counties remain 0 to 2 o F cooler than normal. Daytime temperatures have been 1 to 4 o F warmer than average across the state, and the warmest conditions were found in southern Pima, southern Yavapai and central Navajo counties. The northern 2/3 of Arizona has received over 100% of normal precipitation with a few drier than normal pockets in southern Mohave and central Apache counties. The southern third of the state has been dry, receiving less than 90% of normal precipitation. 16

August Mean Temperature Graphs Flagstaff, Phoenix, and Tucson 1895-2017: 17

August Mean Precipitation Graphs Flagstaff, Phoenix, and Tucson 1895-2017 18

2017 Cumulative Precipitation Graphs Flagstaff, Phoenix and Tucson: Flagstaff is 3.39 above normal, Tucson is 2.24 above normal, and Phoenix is 0.55 below normal. 19

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) 20