The region, like most of the U.S., had a cool year, with the city coming in around three-quarters of a degree below average. Temperatures reached as high as 103, late in the Summer, on August 30, and the coldest reading was 7 on December 24th. There were only 46 days with a high of 90 or greater, compared to 73 in 2012 and 68 in 2011. 18 days were recorded where the high temperature remained below freezing and there were 104 days with lows below freezing. No days recorded below zero temperatures.
St. Louis temperature stats.
The year alternated cool and warm periods, and the year began on a warm note, which had started in August 2012 and continued until mid February. This was approximately a 120 day period of warmth, which extended through the first 45 days or so of 2013. The weather pattern flipped at that point and a 100 day cool period began, lasting through early July. A temporary burst of warmth re surged early in the summer, then gave way to a cooler period for mid summer. A second 45 day period of warmth ran from Mid August until early October. This stretch included the year’s hottest temperature, on September 8th. An extended and often sharply colder pattern took hold after that and lasted beyond the year’s end.
2013 was characterized by long stretches of warm and cool periods, but the predominate mode was cool.
Despite a pronounced dry trend late in the year, St. Louis goes down above average in terms of rain for 2013, due to a wet early and mid 2013.
2013 finishes just under 2″ above average.
St. Louis fell behind right out of the gate in January but made up ground by the end of January. For the remainder of the year, totals were above average. Rainfall notably decreased late in the year, with a moderate drought developing, but the built-up surplus was enough to keep the yearly totals above average.
St. Louis 2013 rain and snowfall.
Taking a wider view of the region; here is a look at the average annual rains, departure (or difference) from average and the percent of average rains for 2013.
Average yearly rains over Missouri and S Illinois.
Observed precipitation for 2013. The darkest reds depict 60″ rainfall totals over the SW and SC Missouri Ozarks and parts of SE Illinois. 50″ totals were over much of the rest of SW Missouri due to repeating summer rains and SE Missouri and SE Illinois thanks, in part to heavy December rains. Northern and NW Missouri to just NW of KC had 25 to 40″ of rainfall with a small area of NW and NE Missouri having 20-25″ of rainfall.
This graphic clearly shows which areas received the heaviest rains and which areas were missed in large part.
Percent of average rainfall.
Despite the wet year, large-scale oceanic conditions tilt the odds in favor of summertime drought and winter dryness and this may be a pattern which holds several more years, so the wet weather could come to an end in 2014.
Average drought frequency for the Midwest/Plains for a negative Pacific multidecadal oscillation (-PDO) and a positive Atlantic multidecadal oscillation (+AMO). These oscillations slowly change states over a period of 10-20 years. The current pattern, became established in the late 2000s. The +AMO has been in place since 1995, while the -PDO since 2008. In its current state, the odds are tilted towards drought in Kansas City 30% of the time or 3 in every 10 years. When the +AMO becomes a -AMO, which may occur shortly, drought frequency drops to near average (2 in every 10 years or once in every 4 years.)
A wide variety of weather characterized 2013, here are a few of the highlights:
The Palm Sunday snowstorm:
The Palm Sunday snowstorm brought significant snows to the St. Louis Metro, but bypassed areas to the south.
Summer makes a late, and powerful, entrance:
Oppressive heat was late arriving to the region, not taking hold until mid August and after.
Late October’s first freeze:
The first freeze hit a little ahead of schedule on October 25th. Low temperatures that morning.
Typhoon Haiyan helps fuel a change in our weather pattern mid November:
A record breaking western Pacific Typhoon 8,500 miles away helped force a change in our jet stream pattern to turn the corner to a much colder regime.
That change fuels severe weather:
November 17, 2013: A tornadic thunderstorm passes just north of Chester.
Severe weather watches and warnings:
Severe weather watches (tornado-pink) and warnings (tornado-red)
Severe weather reports:
These are storm reports shown through early Sunday afternoon. Washington and Clinton Counties had tornado reports, with funnel clouds in Williamson and Franklin Counties of S Illinois. Lots of wind and hail reports elsewhere.
The Pearl Harbor Day snowfall:
Snowfall from the December 7-8, 2013 snowstorm.
The winter solstice rains:
Heavy rain and flooding the story on the eastern side of the district, with a persistent band of heavy rains setting up SE of St. Louis and concentrating over SE Missouri and S Illinois. Two day totals are listed here.