September was on the warm side of average in Lawrence with rainfall near to slightly below normal.
The average high at the Lawrence Airport was 83.6 degrees, which was 2.3 degrees above normal. The average low was 58.3 degrees, some 3.4 degrees above normal. The mean monthly temperature was 2.8 degrees above normal.
Noteworthy was the fact that the 83.6-degree average high for September was actually slightly warmer than the 83.5 average high registered in August, a month when the mean temperature was nearly 5 degrees below normal.
Warmest for the month was a 92-degree reading on the 22nd. Interestingly, this was also the warmest reading of our unusually cool August.
The coolest reading of the month occurred on the 6th when the temperature at the airport dropped to 43 degrees, the coolest reading since the 13th of May.
Precipitation-wise, the total at the Lawrence Airport for September was 3.47 inches, compared to an average of 4.16 inches.
A volunteer network of 7 professional precipitation observation sites within Lawrence came in with an average of 3.59 inches for the month. Individual amounts in the city network ranged from 2.8 inches in northwest Lawrence near Peterson and Folks to 4.33 inches in the southwest part of town near 27th and Crossgate.
For the year to date, the Lawrence city average precipitation is up to 39.06 inches, compared to a normal through September of 32.02 inches, or 122 percent of normal. Average annual precipitation in Lawrence is 38.55 inches, a figure already exceeded by the city precipitation network.
The city precipitation total for the year differs significantly from the airport total due to malfunctions of the automated equipment at the airport in previous months. For September, however, the airport rainfall readings appeared to be accurate and complete.
Some interesting facts about September this year include:
No measurable rainfall occurred from the 28th of August through the first half of September – a 19-day dry spell. This was broken by the significant rainfall event of the 16th and 17th when about 2.6 inches of rain fell across the area.
Most of the remainder of the precipitation in the month fell on the 18th, 25th and 26th. This amounted to only three separate significant rainfall events that occurred during the month.
The coolest day of the month was the 6th when the high of 75 and low of 43 brought a mean temperature of 59, some 13 degrees below the average for the date.
The warmest day of the month was the 21st when a high of 92 and low of 73 brought the mean to 83, some 17 degrees above average for the date.
Much of the first half of the month featured hazy skies resulting from smoke layers aloft. The persistent smoke layers aloft resulted from widespread wildfires, mainly across the Pacific Northwest and northern Rockies. This brought a series of bright red and interesting sunrises and sunsets during much of the first half of the month. The wildfires were mostly doused out by the major storm system that eventually brought heavy rains to our area mid month.
A 7-day warm spell occurred from the 19th though the 25th of the month. During this period, the average high was 90 degrees and the average low was 69, an exceptional 14 degrees above normal. The coolest daily maximum temperature of the month occurred right after this warm spell on the 26th when the high reached 67.
The month ended on the warm side with the last two days reaching a high of 81.
A very strong jet stream pushing into the western US looks to bring some interesting weather changes for our area during the first half of October!