For the state of Iowa, the average temperature was 69.0°F which was 4.6°F below normal for the month of July (See Figure 1). July 2014 is now the 5th coolest July on record for the state among the 142 years of records.* The average temperature for the Des Moines County Warning Area (CWA) was 68.8°F with the coldest spots located over the west-central and far southeast portions of the CWA (See Figure 2).
There were a few individual days that rose above normal, but no extended heat wave occurred during the month. The hottest days of the month were on the 12th, 21st, 22nd, and 25th when several locations rose into the lower 90s (See Figure 3). The hottest temperature of the month, within the Des Moines CWA, was 95°F at Osceola on the 22nd. The highest temperature throughout the entire state was 102°F on the 25th at Sidney in far southwest Iowa. Des Moines reached at least 90°F only 3 times during the month and normally averages 10 days with 90°F or greater during the month of July. In similar fashion, Waterloo only had 1 day that topped 90°F but normally averages around 8 days with maximum temperatures reaching 90°F or higher in July. Mason City continued its streak of not reaching 90°F in July as the highest temperature at the station was 89°F. By the end of the month, this streak extended to 325 days since the last time the station reached 90°F on September 9, 2013.
On the flip side, there were many more colder than normal days in July. Table 1 illustrates how often central Iowa was below normal during the month. Ottumwa set a couple of new daily temperature records. The first was a daily low maximum temperature of 65°F on the 2nd which broke the previous record of 67°F set back in 1944. The second record was a record low of 49°F set on the 16th breaking the previous record of 51°F in 1930. Lamoni also set a new record low temperature of 52°F on the 16th, breaking the previous record of 55°F set in 1961. Another record low maximum of 66°F was set at Waterloo on the 2nd breaking the old record of 67°F from 1941.
Little precipitation fell during the month of July 2014 across central Iowa and there was only one major severe weather event and that occurred on July 6. Other than southeast Iowa, the remainder of the state was well below normal for precipitation (See Figure 4). The majority of the precipitation only fell on a handful of days which includes the 5th, 6th, 12th and the 25th. The Des Moines International Airport recorded 1.99” on the 5th, while several other locations recorded at least an inch of rain on the same day (See Figure 5). The highest precipitation total during the month, for the state and DMX CWA, was in Montezuma in Poweshiek County with a monthly total of 10.21 inches. The lowest monthly total for the state also occurred in the DMX CWA and that was 0.71 inches at Atlantic in Cass County.
A total of 9 tornadoes occurred on July 6, 2014, 8 dropped down in the DMX CWA. There were two tornadoes rated EF1 and they occurred near the towns of Reinbeck and Dinsdale. The rest were EF0 tornadoes and you can find more information about the event as well as all the tornadoes from 2014 our Tornado Page.
The Saylorville Reservoir pool height rose a about 7 feet during the first week of July to 877.57 feet on the 6th before gradually falling throughout the rest of the month to 851.50 feet on the 31st (See Figure 6). The maximum pool height corresponded to a maximum storage of 446,670 Acre-feet on the 6th while the lowest storage of the month was 171,070 Acre-feet on the 31st. The Des Moines River downstream of Saylorville Lake maximum stage height was 14.29 feet on the 7th and the lowest was 8.45 feet on the 31st. The maximum outflow at the same location was 19,500 CFS on the 2nd to a minimum of 5,600 CFS on the 31st.
Lake Red Rock Reservoir pool height rose from 755 feet on the 1st to 766 feet during the middle of the month before dropping back to around 757 feet by the 31st (See Figure 7). The pool storage nearly reached 1,000,000 Acre-feet when it maxed out at 910,820 Acre-feet on the 11th. The lowest storage was 483,840 Acre-feet on the 1st. The stage height of the Des Moines River downstream of Lake Red Rock Reservoir ranged from 90.37 feet on the 2nd to 93.69 feet on the 13th. It remained above 93 feet from the 1th to the 28th and it was only below 91 feet the first two days of the month. The outflow from Lake Red Rock increased from 13000 CFS on the 1st to around 22,000 CFS by the 12th where it remained steady until the 29th when it dipped down to 18,400 CFS.
*Statewide averages courtesy of State Climatologist Harry Hillaker: http://www.iowaagriculture.gov/climatology/weatherSummaries/2014/pms201407.pdf