Arizona Climate Summary October 2018 Summary of conditions for September 2018 September 2018 Temperature and Precipitation Summary September 1 st 17 th : The wet pattern from August continued into September with 1.62 falling at Valle on the 1 st as a trough moved through the southwest and high pressure to the east brought moisture into Arizona and New Mexico. The wet pattern continued through the 5 th as rain showers were widely scattered across the state. Totals included 0.59 at Bisbee-Douglas, 1.36 at Elgin, 0.95 at Flagstaff, 0.70 at Grand Canyon Airport, 0.37 at Tucson, 0.75 at Window Rock, 0.29 at Coronado National Monument, and 1.15 at Picacho Peak. By the 6 th, drier air moved into northern Arizona while light showers lingered across the south. While high temperatures during the first week peaked at 105 o F, the dry air during the second week allowed temperatures to rebound into the 107 o F to 113 o F range through the 17 th. Very light rain fell in southern Arizona from the 6 th through the 11 th (less than 0.25 totals) and the entire state was dry from the 12 th through the 17 th. The first freezing temperatures of the year (31 o F) were reported on the 13 th and 14 th at Bellemont. September 18 th 30 tht : By the 18 th, high pressure set up over New Mexico bringing some moisture into Arizona causing showers on the 18 th, 19 th and 20 th. The three day totals included 1.25 at Bisbee-Douglas, 1.10 at Elgin, 0.30 at Flagstaff, 1.10 at Nogales, 0.13 at Deer Valley, 0.17 at Sky Harbor, 1.71 at Safford, 0.27 at St. Johns, 0.11 at Scottsdale, 0.29 at Sonora Desert Museum, 0.76 at Tucson, 0.46 at Valle, 1.08 at Carefree, 0.71 at Cottonwood, 0.21 at East Mesa, 0.58 at Eloy, 0.52 at Navajo National Monument, 0.10 at Petrified Forest, 0.69 at Picacho Peak, and 0.14 at Pinnacle Peak. The warmest daytime temperatures dropped down into the upper 90s during this period. The next 3 days were dry statewide while temperatures rose back to the 103-108 o F range in the southwest deserts. By the 24 th, moisture had returned to the state with light rain falling across northern Arizona. Williams had 0.21 on the 24 th, Navajo National Monument had 0.20 on the 25 th, and Williams and Show Low had 0.01 on the 26 th. By the 27 th, a strong low pressure system started moving across the western U.S. and the high pressure system retreated into Mexico. Dry conditions prevailed across Arizona through the 29 th ahead of Hurricane Rosa which was moving slowly up the coast of Baja California. Arizona remained dry from the 27 th through the 29 th as high temperatures in the southwest deserts ranged from 107 to 103 o F. Nighttime lows during this dry period dropped to 27 o F in Flagstaff and other high elevation locations in northern Arizona, 31 o F at Window Rock, and 32 o F at Springerville. On the 30 th, Bellemont received 0.11 of rain and Yuma received 0.63 as moisture from Rosa reached southern Arizona. During the first 3 days of October, Rosa brought heavy rainfall to central Arizona as a finale to the 2018 monsoon. 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; short-term drought maps for the beginning and end of September 2018; 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. 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 updated through 2017. See p.20 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 2018 Arizona State Climate Office 1
September 2018 Daily Temperature, Precipitation, & Dew Point for Flagstaff, Phoenix, and Tucson 2
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FLAGSTAFF CLIMATE STATISTICS September 2018 This September was the 17 th warmest on record and had no significant ranking for precipitation. Avg Max Temp(F) 76.5 Normal 72.9 Avg Min Temp(F) 43.2 Normal 42.0 Avg Mean Temp(F) 59.8 Normal 57.4 Departure from Normal (F) +2.4 Highest Monthly Avg Temp (F) 62.1 in 1947 Lowest Monthly Avg Temp (F) 52.3 in 1912 Highest Temp this month (F): 82 on 8 th Lowest Temp this month (F): 33 on 27 th Record High (F): 91 on 9/1,2,3/1948 Record Low (F): 20 on 9/22/1912 No temperature or precipitation records this month. Flagstaff Number of Days of: Minimum Temp 45 o F or higher 10 Minimum Temp 40 o F or lower 6 Maximum Temp 80 o F or higher 5 Maximum Temp 70 o F or lower 1 Heating Degree Days 145 Normal 229 Cooling Degree Days 0 Normal 3 Degree base 65 o F Total September Precipitation 1.30 Normal September Precipitation 2.38 Departure from normal -1.08 Greatest 24-Hr Precipitation 0.63 on 2 nd Total Precipitation Year-to-Date 15.66 Departure from Normal -0.91 Total September Snowfall 0.0 Normal Trace Record September Snowfall 2.0 in 1965 Number of Days: Clear 26 Partly Cloudy 4 Cloudy 0 Greatest September Precipitation 6.75 in 1983 Least September Precipitation: Trace in 1992, 1973, 1957, and 1955. Average Wind Speed Highest Peak Gust 4.6 mph 38 mph from 210 o on 12 th PHOENIX CLIMATE STATISTICS September 2018 This September was the 2 nd warmest on record and had no significant ranking for precipitation. Avg Max Temp(F) 103.5 Normal 99.8 Avg Min Temp(F) 80.2 Normal 76.9 Avg Mean Temp (F) 91.9 Normal 88.4 Departure from Normal (F) +3.5 Highest Monthly Avg Temp (F) 92.2 in 2001 Lowest Monthly Avg Temp (F) 78.9 in 1900, 1912 Highest Temp this month (F) 109 on 8 th, 14 th & 15 th Lowest Temp this month (F): 73 on 20 th Record High (F): 113 on 9/5/1945 Record Low (F): 47 on 9/20-21/1965, 9/22/1895 4 Temperature or precipitation records this month: 24 th HiMin 82 tied, first set in 2001 Phoenix Number of Days of: Minimum Temp 75 o F or lower 4 Minimum Temp 85 o F or higher 6 Maximum Temp 100 o F or lower 5 Maximum Temp 105 o F or higher 13 Heating Degree Days 0 Normal 0 Cooling Degree Days 814 Normal 700 Degree base 65 o F Total September Precipitation 0.43 Normal September Precipitation 0.64 Departure from normal -0.21 Greatest 24-Hr Precipitation 0.19 on 3 rd
Total Precipitation Year-to-Date 3.40 Departure from Normal -2.52 Greatest September Precipitation 5.41 in 1939 Least September Precipitation 0.00 in 1968, 1973, 1988 and 13 other years. Number of Days: Clear 21 Partly Cloudy 9 Cloudy 0 Average Wind Speed 6.2 mph Highest Peak Gust 29 mph from 130 o on 3 rd TUCSON CLIMATE STATISTICS September 2018 This September was the warmest on record and had no significant ranking for precipitation. Avg Max Temp(F) 97.5 Normal 94.5 Avg Min Temp(F) 72.3 Normal 68.6 Avg Mean Temp(F) 84.9 Normal 81.6 Departure from Normal (F) +3.3 Highest Monthly Avg Temp (F) 84.9 in 2018 Lowest Monthly Avg Temp (F) 76.3 in 1964 Highest Temp this month (F): Lowest Temp this month (F): 105 on 14 th & 15 th 67 on 20 th Record High (F): 107 on 9/14/2000, 9/10-11/1990 Record Low (F): 43 on 9/26/1913 Heating Degree Days 0 Normal 0 Cooling Degree Days 603 Normal 497 Degree base 65 o F Total September Precipitation 1.14 Normal September Precipitation 1.29 Departure from normal -0.15 Greatest 24-Hr Precipitation 0.76 on 19 th Total Precipitation Year-to-Date 9.00 Departure from Normal -0.20 Greatest September Precipitation 5.60 in 2011 Least September Precipitation 0.00 in 1953, 1898 and 4 other years. Temperature or precipitation records this month: 15 th HiMax 105 tied, first set in 1928 19 th Precip 0.76 set, previous record 0.73 in 1983 24 th HiMin 78 tied, first set in 2001 Number of Days: Clear Partly Cloudy Cloudy M M M Tucson Number of Days of: Minimum Temp 70 o F or lower 10 Minimum Temp 75 o F or higher 7 Maximum Temp 95 o F or lower 9 Maximum Temp 100 o F or higher 11 Average Wind Speed Highest Peak Gust 7.0 mph 56 mph from 90 o on 2 nd Data are from the National Weather Service and the National Climatic Data Center and are preliminary. 5
Wind Speeds for September: Day Phoenix Flagstaff Tucson (mph) Avg Max Avg Max Avg Max 1 7.5 20 7.8 30 10.2 25 2 9.6 28 4.2 18 8.7 56 3 7.5 29 2.8 25 6.1 20 4 6.4 19 3.1 27 7.7 29 5 4.7 15 3.4 20 6.8 27 6 5.8 22 1.9 16 11.1 32 7 5.3 17 2.3 26 9.2 26 8 6.5 18 1.4 16 8.2 23 9 6.9 23 4.7 25 7.9 26 10 7.3 25 5.5 21 5.7 25 11 7 21 7 32 5.9 26 12 7.2 20 9.7 38 7.2 27 13 5 18 6.6 30 5.5 19 14 5 18 3.6 25 5.8 17 15 6.9 20 5.4 31 6.2 22 16 5.6 23 4.6 26 6 17 17 5.2 18 3.5 22 6.7 26 18 7.8 22 6.2 28 7.8 27 19 8.4 26 3.3 17 7.5 25 20 4.2 23 3.6 17 4.5 19 21 5.4 17 2.5 21 6.2 21 22 6.3 17 4.3 20 11.1 32 23 7 0.23 4.8 24 8.4 26 24 6.3 19 5 33 6.1 18 25 4.3 16 3.2 24 5.6 15 26 4.6 13 2.4 25 5 20 27 4.6 16 5.2 32 5.8 16 28 4.7 19 4.7 25 4.9 17 29 6 17 7.7 37 6.2 24 30 7.4 27 6.9 34 5.9 34 Dew Points for September: Daily Average Dew Point ( o F): Day Flg Phx Tuc 1 57 63 45 2 59 60 47 3 57 61 47 4 56 60 45 5 56 55 45 6 53 54 43 7 51 52 43 8 54 54 41 9 55 55 40 10 52 49 38 11 46 46 35 12 40 43 31 13 39 41 29 14 43 42 34 15 54 52 38 16 54 53 44 17 55 56 43 18 65 63 47 19 66 64 44 20 66 62 39 21 57 57 38 22 46 49 37 23 50 55 41 24 43 55 44 25 49 53 41 26 49 50 31 27 47 47 23 28 49 47 34 29 53 50 37 30 51 46 37 6
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September 2018 The minimum temperatures ranged from 22 o F at Meteor Crater and the Grand Canyon East Entrance to 74 o F at Yuma Marine Corps Air Station. The lowest maximum temperature of 70 o F was recorded at Maverick Fork and the highest was 117 o F at Havasu. The highest rainfall totals were 6.34 at Amado in SW AZ and 6.14 at Green Valley. The lowest average dew point was 34 o F at Flagstaff and Page and the highest was 59 o F at Yuma, Coolidge and Paloma. The highest peak wind gust was 40 mph at Mohave. Average wind speeds ranged from 3 mph in many locations to 11 mph at Kingman. 8
T September 2018 The highest average minimum temperature was 81 o F at Falcon Field, and the lowest average minimum temperature was 37 o F at the east entrance to the Grand Canyon, Sunrise Mountain, Flagstaff and Bellemont. The highest average maximum temperature was 109 o F at Bullhead City and Havasu and the lowest average maximum temperature was 63 o F at Snowslide Canyon and Payson. 9
Short term drought maps for August 28 th on left and September 25 th on right. September was not a very wet month for the monsoon in many areas. The southwest and northeast received very little rainfall, while the Mogollon Rim and parts of Coconino and Yavapai counties enjoyed a wet September. The precipitation led to a reduction of Extreme Drought (D3) across the Mogollon Rim and reduction of Severe Drought (D2) in northern Yavapai and southern Coconino counties. 10
The long-term drought map for September shows hydrologic drought, and it is based on precipitation and evaporation using the Standardized Precipitation Evaporative Index (SPEI) over the past 24-, 36-, and 48- months. This depiction is for water resources, not short-term drought (rangeland conditions). Though much of Coconino and northern Mohave County show up as abnormally dry or moderate drought, there are significant water resource issues, such as wells going dry and water hauling. Exceptional Drought (D4) continues in the northeast, east central and southwestern Arizona. 11
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Monsoon 2018 Minimum temperatures during the monsoon were 0-4 o F warmer than average across most of the state with cooler than average spot just south of Flagstaff and in northern Mohave County. Daytime temperatures were within 1 o F of average in south central Arizona, and were 1-3 o F warmer than average across the rest of the state with a few warmer areas in western Maricopa and northern Graham counties. The monsoon was much wetter than average across the western two thirds of the state, largely due to the tropical moisture during the first two weeks of October. While the storms on October 1 st through the 3 rd were monsoon related, the subsequent storms were due to low pressure systems that are typical of fall and winter precipitation. 13
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Calendar Year 2018 Calendar year minimum temperatures across Arizona have been 1 to 3 o F warmer than average, though a few spots in northern Mohave County, eastern Cochise County, east central, and central Arizona have been slightly cooler than average. Daytime temperatures have been 1 to 3 o F warmer than average in southern Arizona, 2 to 4 o F warmer than average in the northern half of the state and 5 o F warmer than average in northern Apache County. Precipitation in the calendar year has been extremely localized, both in winter and during the monsoon. Much of the rainfall in southwestern and central Arizona fell in the first 2 weeks of October. The northeast quarter of the state, La Paz and southern Mohave counties continue to be well below average for precipitation this year. 15
s aham, Cochise, La Paz, OPima and 2018 Water Year Water Year 2018 average temperatures have ranged from 2-4 o F warmer than normal across most of the state. Far east central Arizona was over 5 o F warmer than normal and southern La Paz County was near average. Water Year precipitation was less than 5.00 across the southwest and the northeast and the highest elevations only received around 25.00. This was under 50% of average in the northeastern plateau and the southwest, and near average in the higher elevations of southern Arizona where the monsoon made up for the dry winter. 16
September Mean Temperature Graphs Flagstaff, Phoenix, and Tucson 1895-2018: 17
September Precipitation Graphs Flagstaff, Phoenix, and Tucson 1895-2018 18
2018 Cumulative Precipitation Graphs Flagstaff, Phoenix and Tucson: Flagstaff is 0.91 below normal, Phoenix is 2.52 below normal, and Tucson is 0.20 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