Summer 2015 Climate Summary

Summer 2015 was generally warmer and drier then average.

Temperatures:

Temperatures across the region were generally one to two degrees above normal, with a few exceptions. The table below summarizes the three-month average temperature, high temperature, low temperature and departures from normal for select cities:

City	Jun-Aug 2015 Average Temp	Departure from normal*	Jun-Aug 2015 Average High Temp	Departure from normal*	Jun-Aug 2015 Average Low Temp	Departure from normal*
Cheyenne	67.5	+1.1	81.3	+1.3	53.7	+0.9
Laramie	62.5	+1.3	78.7	+1.9	46.4	+0.9
Rawlins	65.3	+1.5	81.7	+1.6	48.9	+1.3
Alliance	69.3	+0.2	84.3	+0.6	54.3	+0.9
Chadron	70.7	+0.1	85.9	-0.8	55.6	+1.2
Scottsbluff	71.8	+0.7	86.3	-0.2	57.3	+1.7
Sidney	71.2	-0.8	86.7	-0.3	55.4	-1.7

* Based on 1981-2010 normals

The warmest temperatures of the summer and the number of days with highs 90 degrees or higher are depicted for select cities in the table below:

City	Highest Temperature	Date	Number of days 90 degrees or above
Cheyenne	95	August 15	10
Laramie	89	June 21	0
Rawlins	93	June 30	10
Alliance	101	August 15	30
Chadron	105	August 15	37
Scottsbluff	101	August 15	35
Sidney	101	August 26	34

Precipitation:

Precipitation was generally below normal, with a few exceptions. Ample late winter and spring precipitation occurred before the drier summer pattern ensued. The table below tabulates the June-August 2015 precipitation and departures from normal:

City	Jun-Aug 2015 precipitation	Departure from normal*
Cheyenne	4.03	-2.45
Laramie	4.46	+0.26
Rawlins	2.44	-0.19
Alliance	6.06	-0.84
Chadron	6.83	-0.10
Scottsbluff	7.33	+1.35
Sidney	4.75	-3.65

* Based on 1981-2010 normals

Thanks to the wet late winter and spring, abnormally dry conditions were limited to southwest Carbon County in June, then improved in July with the arrival of the summer monsoon. Elsewhere, there were no abnormally dry conditions reported. The images below depict the drought monitor status for the High Plains region:

June 2, 2015 Drought status August 25, 2015 Drought status

Other Notable Weather Events during Summer 2015:

-Thunderstorms across much of southeast Wyoming produced widespread large hail as well as some flash flooding from torrential rainfall on June 3-4. The worst flooding occurred during the predawn hours across southern Niobrara County from Manville to Lusk to Van Tassel.

- Late afternoon and evening thunderstorms produced very heavy rain, strong winds and numerous reports of large hail across central and southern portions of the western Nebraska Panhandle on June 16. Street flooding was observed in Scottsbluff.

- Thunderstorms over the western Nebraska Panhandle produced very heavy rain, strong winds, a weak tornado and numerous reports of large hail on June 25.

- Afternoon thunderstorms on July 3 produced golf ball to baseball size hail across portions of Albany and Laramie counties.

- Four to six inches of rain in three hours caused flash flooding in northeast Laramie County on July 21.

- Late afternoon thunderstorms over the southern Nebraska Panhandle on August 1 produced large hail and damaging wind gusts to 75 mph.

- Thunderstorms over Banner, Cheyenne and Kimball counties produced several funnel clouds, damaging winds and torrential rain on August 10-11.