Riverton 2009 Annual Climate Summary

2009 Climate Summary for Downtown Riverton
Month	Avg High	Avg Low	Average Temp	Departure From Normal	Total Pcpn	Departure From Normal	Snowfall	Avg Snow	Departure
January	35.9	9.7	22.8	7.9	0.25	-0.03	4.8	4.7	0.1
February	45.5	14.4	30.0	7.9	T	-0.25	0.1	4.3	-4.2
March	47.2	18.4	32.8	-2.1	1.15	0.67	15.2	4.4	10.8
April	56.0	31.7	43.9	-0.2	2.02	1.01	14.2	3.8	10.4
May	70.9	41.3	56.1	2.3	0.98	-0.80	0.2	0.4	-0.2
June	73.4	47.1	60.3	-3.4	1.89	0.75	0.0	T	0.0
July	86.2	53.3	69.8	-0.5	1.64	0.91	0.5	0.0	0.5
August	84.0	49.9	67.0	-1.2	0.75	0.26	0.1	0.0	0.1
September	79.1	45.5	62.3	5.0	0.30	-0.58	0.0	0.7	-0.7
October	49.2	27.2	38.2	-6.6	2.30	1.49	19.7	2.5	17.2
November	48.9	19.8	34.4	6.2	0.01	-0.46	0.2	5.0	-4.8
December	21.6	-1.4	10.1	-5.8	0.30	-0.06	7.5	5.3	2.2
Total/Ave	58.2	29.7	44.0	0.8	11.59	2.91	62.5	31.1	31.4

Yearly Extremes: Highest Temperature: 97 Degrees on August 23^rd Lowest Temperature: -28 Degrees on December 9^th Days with Maximum Temperature 90 Degrees F or Higher: 24 Days with Maximum Temperatures 32 Degrees F or Lower: 39 Days with Minimum Temperatures 32 Degrees F or Lower: 184 Days with Minimum Temperature 0 Degrees F or Lower: 26 Most Precipitation in 24 Hours: 1.34 inches on October 5-6^th Most Precipitation in One Day: 1.32 inches on October 5^th Most Snowfall in 24 Hours: 10.0 on October 5-6^th Most Snowfall in One Day: 9.8 inches on October 5^th Highest Wind Gust (Riverton Regional Airport): 68 mph (west-northwest) on January 11^th

Monthly Reviews:

JANUARY 2009 – Much Warmer than Normal Arctic Front - Downtown Riverton Plunges to -21F on the 27^th Riverton’s average monthly temperature was 22.8 degrees which was 7.9 degrees above normal making it the 12^th warmest January on record. Temperatures ranged from 21 degrees below zero on the 27^th to 57 degrees on the 9^th. The monthly precipitation total of 0.25 inches was 0.03 inches below normal. Snowfall for the month was 4.8 inches. The peak wind gust was 68 mph out of the west-northwest on the 11^th.

FEBRUARY 2009 – Much Warmer and Drier than Normal Riverton’s average monthly temperature was 30.0 degrees which was 8.2 degrees above normal making it the 11^th warmest February on record. Temperatures ranged from 4 degrees on the 28^th to 61 degrees on the 26^th. The monthly precipitation total was only a trace which was 0.25 inches below normal. Snowfall for the month was 0.1 inches. The peak wind gust was 67 mph out of the northwest on the 25^th.

MARCH 2009 – Cooler and Much Wetter than Normal Warm Start - Record Highs March 2-3 March 8-10 - 5 Inches of Snow in Riverton Area March 9-11: Cold Follows the Snow Late March Snow Storm Dumps 4 to 7 inches of snowfall in the Riverton area. Riverton’s average monthly temperature was 32.8 degrees which was 2.1 degrees below normal. Temperatures ranged from 10 degrees below zero on the 11^th to 73 degrees on the 22^nd. The monthly precipitation total of 1.15 inches was 0.67 inches above normal. Snowfall for the month was 15.2 inches making it the 4^th snowiest March on record. The peak wind gust was 56 mph out of the west on the 29^th.

APRIL 2009 – Cooler and Drier than Normal April 16-17: Spring Snow Storm Dumps 6 to 9 inches of Snow in Riverton Area Riverton’s average monthly temperature was 43.9 degrees which was 0.4 degrees below normal. Temperatures ranged from 18 degrees on the 6^th to 76 degrees on the 24^th. The monthly precipitation total of 2.02 inches was 1.01 inches above normal which was the 12^th wettest April on record. Snowfall for the month was 14.2 inches making it the 10^th snowiest April on record. The peak wind gust was 59 mph out of the west on the 8th.

MAY 2009 – Warmer and Drier than Normal May 24^th and 25^th: Over an Inch of Rain on the South Side of Riverton The average temperature for Riverton was 56.1 degrees which was 2.1 degrees above normal. The highest reading was 81 degrees which occurred on the 21^st. The lowest reading was 19 which occurred on the 1^st. Total precipitation for the month was 0.98 inches which was 0.80 inches below normal. The peak wind gust for the month and year was 64 mph out of the southwest on the 19^th.

JUNE 2009 – Cooler and Wetter than Normal The average temperature for Riverton was 60.3 degrees which was 3.5 degrees below normal. The highest reading was 86 degrees which occurred on the 30th. The lowest reading was 35 which occurred on the 10th. Total precipitation for the month was 1.89 inches which was 0.75 inches above normal. The greatest daily total was 0.58 inches on the 12^th. The peak wind gust was 63 mph out of the west on the 26^th.

JULY 2009 – Slightly Cooler and Much Wetter than Normal The average temperature for Riverton was 69.8 degrees which was 0.6 degrees below normal. The highest reading was 95 degrees which occurred on the 23^rd. The lowest reading was 39 which occurred on the 16^th. Total precipitation for the month was 1.64 which was 0.91 Inches above normal making it the 13^th wettest on record. The greatest daily total was 1.10 inches on the 5^th. The highest wind gust was 66 mph out of the northwest which occurred on the 21^st.

AUGUST 2009 – Cooler and Slightly Wetter than Normal August 16^th-17^th: Where Did Summer Go? Riverton’s average temperature for the month was 67.0 degrees which was 1.5 degrees below normal. The highest temperature for the month and year was 97 degrees on the 23^rd. The lowest temperature was 39 on the 17^th Total precipitation for the month was 0.75 inches which was 0.26 inches above normal. The day with the greatest rainfall was 0.47 inches on the 16^th. The peak wind gust was 56 mph out of the north on the 3^rd.

SEPTEMBER 2009 – Much Warmer and Drier than Normal The average temperature for Riverton was 62.3 degrees which was 4.9 degrees above normal. The highest reading was 89 degrees which occurred on the 5^th. The lowest reading was 30 which occurred on the 28^th. Total precipitation for the month was a 0.30 inches which was 0.58 inches below normal. The peak wind gust was 59 mph out of the north on the 20^th.

OCTOBER 2009 – 3^rd Coldest and 4^th Snowiest on Record Coldest First 17 Days in Riverton Weather History The average temperature for Riverton was 38.2 degrees which was 6.7 degrees below normal which ties it with 1969 for the 3^rd coldest October on record. The highest reading was 70 degrees which occurred on the 20^th. The lowest reading was 6 degrees on the 10^thwhich shattered the old record by seven degrees. The record low of 6 degrees was also the coldest temperature ever recorded so early in the season and only the second single digit low temperature ever recorded before October 20^th. Total precipitation for the month was a 2.30 of an inch which was 1.49 inches above normal making it the 7^th wettest October on record. The greatest daily precipitation was 1.32 inches on the 5^th. There was 19.7 inches of snowfall during the month with 10 inches of snow falling during the early season storm on the 5^th and 6^th. The 19.7 inches of snow in October made it the 4^th snowiest October on record dating back to 1907. The peak wind gust was 55 mph out of the northwest on the 24^th.

NOVEMBER 2009 – Much Warmer than Normal with only 0.01 inches of Precipitation The average temperature for Riverton was 34.4 degrees which was 6.3 degrees above normal. The highest reading was 67 degrees which occurred on the 7^th. The lowest reading was 10 which occurred on the 15^th. Total precipitation for the month was a 0.01 inches which was 0.46 inches below normal. There was only 0.2 inches of snowfall during the entire month. The peak wind gust was 56 mph out of the southwest northwest on the 11^th.

DECEMBER 2009 – Much Colder with Near Normal Precipitation The average temperature for Riverton was 10.1 degrees which was 5.8 degrees below normal. The highest reading was 50 degrees which occurred on the 22^nd. The lowest reading was 28 below zero which occurred on the 9^th. Total precipitation for the month was a 0.30 inches which was 0.06 inches below normal. The greatest daily precipitation was 0.07 of an inch that fell on the 24^th. There were 7.5 inches of snowfall during the month which was 2.2 inches above normal. The highest wind gust of the month was 61 mph out of the northwest which occurred on the 9^th.

National Weather Service Weather Forecast Office