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Arizona Climate Summary November 2018

Summary of conditions for October 2018

October 2018 Temperature and Precipitation Summary October 1st – 15th: The 2018 water year ending September 30th was exceptionally dry across the state, and the end of September would normally signify the end of the monsoon. However, Hurricane Rosa churned up the Baja coast bringing tropical moisture into the monsoon circulation. Extremely heavy rain fell across much of the state between October 1st and 4th as a result of this moisture source. Heaviest rainfall was in central Arizona. Three day rainfall totals included 2.53” at Flagstaff, 0.80” at Grand Canyon Airport, 1.30” at Kingman, 0.53” at Page, 2.27” at Deer Valley, 2.75” at Phoenix Sky Harbor Airport, 0.47” at Prescott Airport, 0.75” at St. Johns, 3.61” at Scottsdale Airport, 1.52” at Sonora Desert Museum, 1.23” at Valle, 0.49” at Window Rock, 0.75” at Winslow, 0.87” at Yuma, 1.01” at Bellemont, 3.27” at Carefree, 2.26” at Cottonwood, 0.92” at East Mesa, 1.41” at Eloy, 1.47” at Grand Canyon North Rim, 2.23” at Apache Junction, 2.88” at Payson, 3.89” at Pinnacle Peak (including 1.9” of snow), 0.95” at Williams, and 1.60” at Youngtown. This ended the monsoon and began the new water year in spectacular fashion. The state was essentially dry on the 5th and 6th but a strong low pressure system, typical of the fall transition, moved across the western US on the 7th through the 9th, again tapping into significant tropical moisture. Totals from this storm included 0.94” at Flagstaff, 0.60” at Grand Canyon Airport, 0.95” at Deer Valley,0.41” at Sky Harbor, 0.82” at Prescott, 0.66” at Scottsdale, 0.41” at Tucson, 0.91” at Valle, 0.92” at Winslow, 1.02” at Bellemont, 1.42” at Carefree, 1.50” at Payson, 1.80” at Petrified Forest, 1.48” at Pinnacle Peak, 0.88” at Seligman, 1.33” at Show Low, and 0.45”at Springerville. It was relatively dry on the 10th, and the next low pressure system moved through on the 11th and exited the state on the 14th. One day totals included 0.60” at Canyon de Chelly on the 11th, 1.26” at Coronado National Monument on the 12th, 2.19” at Phoenix on the 13th, and 0.67” at Yuma on the 14th. The 15th was dry in central and southern Arizona. During these storm systems temperatures finally dropped down to near average levels, and even set or tied a few low temperature records. October 16th – 31st: Yet another strong low pressure system moved through the state on the 16th and 17th. Precipitation totals were not as high for this storm, but it was much colder and brought snow to northern Arizona. Snow totals included 0.8” at Flagstaff, 3.0” at the Grand Canyon North Rim, and 1.0” at Show Low. Rainfall totals included 0.35” at Bisbee-Douglas, 0.16” at Davis Monthan AFB, 0.29” at Elgin, 0.54” at Safford, 0.38” at St. Johns, 0.41” at Tucson AP, 0.80” at Winslow, 0.40” at Coronado NM, 0.75” at Payson, 0.80” at Petrified Forest, 0.99” at Show Low, and 0.40” at Springerville. The 18th, 19th and 20th were dry statewide as high pressure returned and temperatures in the southwest deserts moved back to the upper 80s and lower 90s. Yet another low pressure system moved through the state on the 21st through the 24th. Bisbee-Douglas has 1.52”, Elgin had 1.67”, Tucson had 0.57”, Winslow had 0.46”, Coronado NM had 1.11”, Douglas had 0.90”, Payson had 0.41”, Pinnacle Peak had 1.28”, and Williams had 0.21”. The state was dry from the 25th through the 29th as high pressure moved in from the west. On the 30th another low pressure system passed through the state and brought light showers to northern and eastern Arizona. October was an extremely wet month dropping 100 to 800% of normal precipitation on the state and setting a number of rainfall records. It was a welcome change to the dry conditions of the previous 14 months. In This Issue: Overview of October, graphs of the October daily maximum and minimum temperatures, precipitation, mean daily dew points for Flagstaff, Phoenix, and Tucson; October climate statistics, maps of mean monthly maximum and minimum temperatures, precipitation, dew points, wind speeds for October; short-term drought maps for the beginning and end of October 2018; Long-term Drought Map through October and graphs of the mean October 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.

Dr. Nancy J. Selover, State Climatologist http://azclimate.asu.edu 480-965-0580 Edited by Nancy J. Selover © 2018 Arizona State Climate Office

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**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. October 2018 Daily Temperature, Precipitation, & Dew Point for Flagstaff, Phoenix, and Tucson

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FLAGSTAFF CLIMATE STATISTICS October 2018

This October had no significant ranking for temperature and was the 7th wettest on record. Avg Max Temp(F) 56.7 Normal 62.0 Avg Min Temp(F) 34.3 Normal 31.5 Avg Mean Temp(F) 45.5 Normal 46.8 Departure from Normal (F) -1.3 Highest Monthly Avg Temp (F) 52.5 in 1988 Lowest Monthly Avg Temp (F) 38.6 in 1971 Highest Temp this month (F): 71 on 27th Lowest Temp this month (F): 25 on 18th 31st Record High (F): 85 on 10/1/1980 Record Low (F): -2 on 10/30/1971 Temperature and precipitation records this month. 2nd HiMin 52 set, previous record 49 in 1951 2nd Precip 2.30” set, previous record 1.03” in 1981 3rd HiMin 52 set, previous record 50 in 1989 7th LoMax 47 tied, first set in 2011 16th LoMax 36 set, previous record 38 in 1994 Flagstaff Number of Days of: Minimum Temp 40oF or higher 5 Minimum Temp 30oF or lower 10 Maximum Temp 70oF or higher 6 Maximum Temp 50oF or lower 6

Heating Degree Days 598 Normal 566 Cooling Degree Days 0 Normal 0 Degree base 65oF Total October Precipitation 4.21” Normal October Precipitation 1.66” Departure from normal 2.55” Greatest 24-Hr Precipitation 2.30” on 2nd Total Precipitation Year-to-Date 19.87” Departure from Normal +1.64” Total October Snowfall 1.5” Normal 1.5” Record October Snowfall 24.7” in 1971 Number of Days: Clear 16 Partly Cloudy 9 Cloudy 6 Greatest October Precipitation 9.86” in 1972 Least October Precipitation: 0.00” in 2017, 1917, 1902 and 6 other years. Average Wind Speed 6.7 mph Highest Peak Gust 38 mph from 050o on 31st

PHOENIX CLIMATE STATISTICS October 2018

This October had no significant ranking for temperature and was the wettest October on record Avg Max Temp(F) 83.0 Normal 88.5 Avg Min Temp(F) 64.5 Normal 64.8 Avg Mean Temp (F) 73.8 Normal 76.7 Departure from Normal (F) -2.9 Highest Monthly Avg Temp (F) 82.7 in 2003 Lowest Monthly Avg Temp (F) 66.1 in 1916 Highest Temp this month (F) 93 on 20th Lowest Temp this month (F): 57 on 7th

Record High (F): 107 on 10/1, 2/1980 Record Low (F): 34 on 10/30/1971 Temperature or precipitation records this month: 2nd Precip 2.36” set, previous record 0.59” in 1981 7th Precip 0.41” set, previous record 0.01” in 1972 7th LoMax 77 tied, first set in 2011 13th Precip 2.19” set, previous record 0.14” in 1933 Phoenix Number of Days of: Minimum Temp 60oF or lower 8 Minimum Temp 70oF or higher 4 Maximum Temp 80oF or lower 9 Maximum Temp 90oF or higher 2

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Heating Degree Days 1 Normal 6 Cooling Degree Days 279 Normal 367 Degree base 65oF Total October Precipitation 5.35” Record Normal October Precipitation 0.58” Departure from normal 4.77” Greatest 24-Hr Precipitation 2.36” on 2nd Total Precipitation Year-to-Date 8.75” Departure from Normal +2.25”

Greatest October Precipitation 4.40” in 1972 Least October Precipitation 0.00” in 2017, 1999, 1995 and 19 other years. Number of Days: Clear 12 Partly Cloudy 18 Cloudy 1 Average Wind Speed 7.0 mph Highest Peak Gust 54 mph from 340o on 7th

TUCSON CLIMATE STATISTICS

October 2018 This October had no significant ranking for temperature and was the5th wettest on record. Avg Max Temp(F) 80.3 Normal 84.8 Avg Min Temp(F) 59.0 Normal 57.3 Avg Mean Temp(F) 69.6 Normal 71.0 Departure from Normal (F) -1.4 Highest Monthly Avg Temp (F) 77.5 in 2016 Lowest Monthly Avg Temp (F) 63.1 in 1920 Highest Temp this month (F): 91 on 28th Lowest Temp this month (F): 51 on 9th Record High (F): 102 on 10/01/2010, 10/03/1993 Record Low (F): 26 on 10/30/1971 Temperature and precipitation records this month: 13th LoMax 67 set, previous record 72 in 2008 13th Precip 0.69” set, previous record 0.55” in 1916 20th HiMin 66 tied, first set in 1947 Tucson Number of Days of: Minimum Temp 55oF or lower 8 Minimum Temp 70oF or higher 2 Maximum Temp 75oF or lower 10 Maximum Temp 85oF or higher 10

Heating Degree Days 11 Normal 24 Cooling Degree Days 162 Normal 212 Degree base 65oF Total October Precipitation 2.87” Normal October Precipitation 0.89” Departure from normal +0.98” Greatest 24-Hr Precipitation 0.69”on 13th Total Precipitation Year-to-Date 11.87”

Departure from Normal +1.78” Greatest October Precipitation 4.98” in 2000, 1983 Least October Precipitation 0.00” in 1982, 2013, 2017 and 17 other years. Number of Days: Clear M Partly Cloudy M Cloudy M Average Wind Speed 8.3 mph Highest Peak Gust 42 mph from 120o on 20th Data are from the National Weather Service and the National Climatic Data Center and are preliminary.

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Wind Speeds for October: Day Phoenix Flagstaff Tucson (mph) Avg Max Avg Max Avg Max 1 5 15 4.1 19 4.5 18 2 8 27 7.3 30 8.9 30 3 3.4 12 7 22 5.6 21 4 6.2 17 11 32 4.8 21 5 4.2 15 3.1 21 5.8 23 6 6.9 24 9.9 35 7.9 28 7 9 54 7 25 9 34 8 7.2 20 5.5 19 7.6 24 9 4.9 18 7.1 24 7.2 23 10 6.3 18 7.4 25 7 23 11 8.7 23 6.5 27 6.4 27 12 6.9 22 6.8 19 10.1 32 13 8.5 26 3.9 25 5.5 17 14 5.2 17 7.6 26 4.8 23 15 9.5 27 16.7 37 5.2 21 16 11.6 30 11.2 29 10.8 34 17 11.2 24 6.4 17 15.6 40 18 8.2 24 5 18 12.3 36 19 8 26 13.9 33 10.9 28 20 11 26 7 23 18.3 42 21 10.4 27 4.9 25 17.1 39 22 6.1 19 4.4 25 10 24 23 6.5 33 2.9 18 9.9 39 24 4.4 13 2.4 22 6.6 18 25 5.7 15 3.5 23 6.7 14 26 4.1 17 5.2 26 5.4 15 27 3.9 15 1.8 15 6.1 20 28 4.6 16 2.8 20 7.1 15 29 5.5 13 8.1 28 7 25 30 8.7 20 7 26 8.3 29 31 6.9 21 10.4 38 4.8 19

Dew Points for October: Daily Average Dew Point (oF): Day Flg Phx Tuc 1 71 64 53 2 71 65 51 3 66 60 49 4 61 52 43 5 56 46 40 6 54 51 34 7 52 45 36 8 48 45 32 9 46 42 34 10 50 46 38 11 56 55 40 12 60 58 41 13 60 56 40 14 52 56 23 15 49 50 27 16 42 44 29 17 46 45 31 18 46 48 31 19 52 52 35 20 50 52 38 21 55 55 41 22 57 58 42 23 54 53 38 24 55 52 33 25 52 50 33 26 47 47 28 27 47 46 28 28 49 46 32 29 50 46 34 30 36 38 25 31 44 47 34

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October 2018 The minimum temperatures ranged from 3oF at Snowslide Canyon to 59oF at Yuma Marine Corps Air Station. The lowest maximum temperature of 39oF was recorded at McNary and the highest was 107oF at Bullhead City. The highest rainfall totals were 8.45” at Scottsdale and 7.81” at Pinnacle Peak. The lowest average dew point was 36oF at Clark Memorial Field and Flagstaff and the highest was 56oF at Paloma. The highest peak wind gust was 40 mph at Mohave.

Average wind speeds ranged from 2 mph at Phoenix-Encanto to 13 mph at Laughlin.

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October 2018 The highest average minimum temperature was 66oF at Laughlin, and the lowest average minimum temperature was 28oF at Sunrise Mountain. The highest

average maximum temperature was 89oF at Yuma and the lowest average maximum temperature was 48oF at Snowslide Canyon.

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Short-term Drought

Short term drought maps for September 25th on left and October 30th on right. October was a very wet month in most of the state with the exception on the far northeast. Heavy rainfall from several tropical storms provided relief from short term drought. The percentage area of Exceptional Drought (D4), Extreme

Drought (D3), and Severe Drought (D2) was reduced by half.

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The long-term drought map for October 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. This map replaced the relatively dry Octobers of 2016, 2015 and 2014 with the extremely wet October of 2018, so it is likely showing more drought relief than probably occurred as many of the aquifers do not recharge rapidly, though run-off into the reservoirs and lakes may have been significant.

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October 2018

Minimum temperatures were 2-4oF warmer than average across northern and western Arizona while central and south central Arizona ranged from 2oF warmer to 4oF cooler than normal. Eastern Yavapai County was 4 to 8oF cooler than normal. Daytime temperatures were 2 to 6oF cooler than average across

the state. October precipitation was 125 to 1200% of average with the wettest conditions in south central Arizona.

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Calendar Year 2018

Calendar year minimum temperatures across Arizona have been 1 to 4oF warmer than average, with northern Mohave County, eastern Cochise, western Gila and eastern Yavapai counties slightly cooler than average. Daytime temperatures have been 1 to 3oF warmer than average in southern Arizona, 2 to 4oF

warmer than average in the northern half of the state and 5oF 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.

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2019 Water Year Nighttime temperatures were 2-4oF warmer than average across northern and western Arizona while central and south central Arizona ranged from 2oF

warmer to 4oF cooler than normal to start the water year. Eastern Yavapai County was 4 to 8oF cooler than normal. Daytime temperatures were 2 to 6oF cooler than average across the state, but the cooler than normal temperatures are not likely to continue through the water year. The first month of the water year saw record precipitation, 125 to 1200% of average with the wettest conditions in south central Arizona. This is a much better start than the 2018 Water

Year.

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October Mean Temperature Graphs – Flagstaff, Phoenix, and Tucson 1895-2018:

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October Precipitation Graphs – Flagstaff, Phoenix, and Tucson 1895-2018

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2018 Cumulative Precipitation Graphs – Flagstaff, Phoenix and Tucson: Flagstaff is 1.64” above normal, Phoenix is 2.25” above normal, and Tucson is 1.78” 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)