Past IEM Features tagged: sep
80+ in September
13 Sep 2023 05:30 AMThe weather this week has generally been a treat for early fall with crisp mornings and comfortable highs in the 70s. The forecast has a chance for a few upcoming days in the low 80s for highs, which is certainly something typical for this time of year as shown by the featured chart. The chart presents the daily frequency of having a high temperature of at least 80 degrees for Des Moines during September. There's a remarkable difference between the start and end of the month. There's also an interesting bump in frequency around 15th through 20th, which is difficult to easily explain away. The moral of this story is that such warm days should be enjoyed as we creep closer to October and such days increasing fleeting.
Voting:
Good: 10
Bad: 0
Tags: sep
Warmest Day of September
20 Sep 2022 05:30 AMTuesday will be remarkably warm for the 20th of September with high temperatures in the 90s and lows near 70. For at least Des Moines, it is possible that both values will be the warmest this month. Is it common to have the warmest high or low temperature this late into the month? The featured chart addresses that very question with the daily frequency of the given day having the highest high or low temperature for that month in a given year. Overall frequencies are higher during the first week to ten days as one may expect as the period is closest to summer and features higher receipts of solar energy than the later portions of the month. There is kind of an interesting blip higher during the 17th to 21rst period for high temperature that may be related to the combination of sufficient heating, warm and dry soil temperatures, and lower atmospheric humidity due to senescence, but it could be a coincidence as well!
Voting:
Good: 11
Bad: 1
Tags: sep
September Min Low
25 Sep 2019 05:30 AMIt has not felt too much like fall yet as the warmth and humidity have been persistent for much of this September. For Des Moines, the minimum temperature so far this month is only 54 degrees. The featured chart presents the minimum temperature each September on record for the site. Of course, this September has a few more days to go, but the current value is four degrees warmer than the previous warmest value of 50. The chart also shows a 30 year rolling average and the recent years have certainly pulled the average warmer. The forecast has a couple of chilly nights ahead and likely a temperature lower than 54, so it remains to be seen if we can eek out a record this year.
Voting:
Good: 11
Bad: 0
Tags: sep
Steamy September
17 Sep 2019 05:32 AMAfter a taste of fall during August, we have leap back into summer with very muggy and warm conditions for September. The featured chart presents the number of hours each September that the dew point temperature was above 70 degrees for Des Moines. The good news is that the current warm weather is extending the growing season, but the warm, wet, and muggy conditions are likely helping to aid some pathogens in the agricultural crop fields. The forecast for this week continues the summer weather!
Voting:
Good: 10
Bad: 0
Tags: sep
September 90+ Days
27 Sep 2017 05:34 AMThe cold front on Monday gave us a break from the very warm conditions for late September. For Des Moines, five days this month were 90+ degrees for high temperature. The featured chart displays the number of 90+ degree days for September. While having five days is double the long term average, there have been plenty of recent years with as many days and the record number of sixteen days is triple of 2017. It remains to be see if we will hit 90 degrees again this fall, but very warm weather looks possible was we start off October.
Voting:
Good: 9
Bad: 0
Tags: sep
Muggy September Days
26 Sep 2016 05:22 AMThe weather feels much more like fall now after a very muggy and summer-like previous week in September. The featured chart presents the number of days each September that the maximum hourly dew point was at or above 70 degrees. This year's total is similarly anomalous to last year's total with the long term average near 3 days. The year of 1978 comes up as the winner in this chart with thirteen days shown.
Voting:
Good: 7
Bad: 1
Tags: sep
Coldest Day of September
24 Sep 2015 05:38 AMThe coldest high and low temperature this month for Des Moines happened on the 11th for high and 12-13th for low. The featured chart presents the frequency of a given day in September being the coldest for that month during one year. Intuitively, the highest frequencies occur toward the end of the month as our average temperatures slide into fall. The forecast has warm temperatures up until next Wednesday, so there is a chance that these early September lows will be the coldest this year.
Voting:
Good: 10
Bad: 13
Abstain: 4
Tags: sep
September Temps + Winds
15 Sep 2015 05:41 AMTemperatures warmed very nicely into the 80s on Monday thanks to the strong southerly wind. The featured chart displays the frequency of having a 10+ knot wind speed at a given air temperature in September. With an increasing temperature there is an increasing chance that we strong winds as well. There is a good reason for this relationship as it takes strong winds to transport warm air into the state and also indicates that vertical mixing is taking place which brings warm air from above to the surface. Without these processes, it is very difficult to support very warm temperatures in September.
Voting:
Good: 11
Bad: 8
Abstain: 2
Tags: sep
Streak above 70 in September
07 Sep 2015 05:41 AMSeptember has been very warm so far with the temperature at the Des Moines Airport at or above 70 degrees for nearly the past 6 days. Based on hourly reports, this streak above 70 is the longest on record for the site in September as shown by the featured image. The previous longest streak was back in 2013 and only another streak back in 1938 was longer than five days. Cooler air is settling into the state today, but as of this posting the temperature remains above 70 for Des Moines, so the streak continues!
Voting:
Good: 17
Bad: 7
Abstain: 6
Tags: sep
80s in September
24 Sep 2014 05:38 AMThere is some hope that we'll reach 80 degrees later this week as our stretch of very nice fall weather continues. The featured wind rose presents the wind direction and speed frequencies when Ames September temperature is at or above 80. The dominate wind direction is clear with southerly winds the most common, which makes sense as it is our source of warmer air. The winds will be out of the south for much of the rest of the week, but speeds are not expected to be all that strong.
Voting:
Good: 11
Bad: 7
Abstain: 5
Tags: windrose sep
September warmer than July
09 Sep 2013 05:38 AMFor the month to date, the average temperature for 1-8 September has been warmer than 1-8 July for Des Moines. The featured chart shows the frequency of this happening for the first of each month to the given date. For the 8th, about one in five years have seen this happen. The forecast has parts of Iowa near 100 degree today with cooler weather expected by the end of the week. If Des Moines were to hit 100 degrees today, it would be the latest into the year for such a warm temperature.
Voting:
Good: 62
Bad: 11
Tags: sep jul
Higher September Humidity
04 Sep 2012 05:45 AMMuggy weather returned over Labor Day weekend with humidity levels running more like what we would have expected in August. For Des Moines, the dew point on Monday was slightly higher than even the highest dew point for all of August. The featured chart shows the yearly combination of highest September versus August dew point. Points above the one to one line would represent years like this year with a higher dew point in September. This combination is somewhat rare and last happened in 1998.
Voting:
Good: 36
Bad: 5
Tags: aug sep
Making up deficits in September
20 Sep 2011 05:56 AMAccording to IEM estimates, the statewide precipitation departure since 1 May was around an inch for the period up until 1 September. The featured chart compares the departure from 1 May until 1 September and 1 October for years back to 1893. Seven out of 59 years whereby the departure was negative on 1 Sep was the September total able to push departure into positive territory.
Voting:
Good: 8
Bad: 4
Tags: sep
Plenty cool for September
19 Sep 2011 05:41 AMThe last five days have seen a remarkable stretch of cool weather with daily high temperatures in the 50s and lower 60s. The featured chart shows the past five days being the coldest on-average for any five day period prior to 19 September since 1903 for Ames! The forecast calls for a warm up to closer to normal high temperatures along with some more chances of rain.
Voting:
Good: 14
Bad: 5
Tags: sep11 sep