Iowa Monthly Climate Summary – June 2016

Temperatures

The statewide monthly average temperature was 73.2°F or 3.5°F above normal (See Figure 1). June 2016 ranks as the 14th warmest June among 144 years of statewide climate records. A warmer June was last recorded in 1991. The average temperature at Des Moines and Waterloo was 77.3°F and 71.9°F respectively.  Des Moines was 5.5°F above normal while Waterloo was only 1.9°F above its monthly average. On the 15th, the hottest temperature of 96°F was recorded for the month at Des Moines while the coldest temperature was 56°F on the 2nd. The hottest temperature at Waterloo was 95°F on the 10th while just two days earlier the low temperature dropped to 46°F.

Above normal temperatures prevailed for the majority of month of June across the state. A long hot spell occurred from the 9th to the 20th when the hottest temperature of 100°F was recorded at Little Sioux on the 11th (See Figure 2). This 100°F ended up being the hottest temperature for the entire state during June 2016 and was Iowa’s first triple-digit temperature since September 10, 2013. The state’s second longest streak without a 100°F reading ended on the 11th with 1,004 consecutive days. The longest streak is 1,438 consecutive days from August 3, 1991 to July 9, 1995.  The maximum temperature at Des Moines from the 9th to the 27th was 85°F or higher for 19 consecutive days in June.  This became the longest streak of its kind during the month of June since 1878 at Des Moines. The previous longest stretch was 17 consecutive days set in June 1956.

Precipitation

The statewide average precipitation was 3.69 inches which was 1.33 inches below the state’s normal for June (See Figures 3 & 4). This ranks as the 45th driest June out of 144 years of statewide climate records. The monthly totals at Des Moines and Waterloo were 1.47” or 3.47” below normal and 8.97” or 4.98” above normal. Des Moines recorded its 10th driest June since 1878 and Waterloo recorded its 4th wettest June since 1895. This was common throughout the state as the precipitation was highly variable (See Figure 5). For example, Cedar Falls had a whopping 11.22” while Salem only recorded 0.25” for the entire month. By the end of the month, much of south central to southeast Iowa were placed into Moderate Drought by the U.S. Drought Monitor with much of the southwest to western part of the state classified as Abnormally Dry (See Figure 6). Severe weather was limited throughout the month of June, even though June is Iowa’s peak severe weather month. In fact, the first half of 2016 was fairly “quiet” with respect to severe weather (See Figures 7a/7b).  The most active day came on June 14th when several central to northern Iowa counties reported wind damage. Heavy rain and damaging winds plagued a few counties during the evening of the 25th into the early morning on 26th (See Figure 8). Flooding was also limited during the month with only 1 river reaching flood stage and just a handful of Flash Flood Warnings issued by National Weather Service Office in Des Moines.

Blog post by Kenny Podrazik, Meteorologist, NWS Des Moines

Summer 2016 Central Iowa Fire Weather News

It has been a slow fire weather season.  The spring was cool and damp and warm season grasses were a little slower to green up.  As we transitioned into June we did warm up and were dry but grass fires, or at least grass fires that were known by the NWS, were minimal.  As we went into July, we continued to have hot spells though any period of heat through mid July was both preceded and followed by a cooler spell which again helped keep grass fires in check.

As we roll into fall we will be preparing for the fall fire weather season which will begin on September 1st.  Beginning September 1st we will be issuing the Fire Weather Planning Forecast twice a day…at 6 am and by 4 pm daily.  We will also be alert to the potential for red flag warnings as we head into harvest season then late fall.  In addition, we will use crop curing as a guide to fire danger during the months of September and October and transition to prairie grass curing in later October through mid November.   We have found that using these two different fuels in the fall better assesses the fire threat and will alert people to the proper threats.  The threats will be displayed in the form of a state map on the fire weather web page of our website.  Please check out http://www.weather.gov/dmx/fire for the latest fire weather forecasts.

Assessment of prairie grass curing is provided by local County Conservation Board employees.  They provide the National Weather Service with curing values of prairie grass on a weekly basis through the entire dry down of the grass and I would like to take this time to recognize their efforts in helping us to provide the most accurate forecast and warning service possible.

As we head into the fall season I would like to remind everyone to heed forecasts and warnings of dry conditions.  Harvesting in extreme dry and windy conditions is the number one cause of crop fires in the fall and crop fires by far exceed any other cause of fall fires.

Blog Post by Frank Boksa, Meteorologist, NWS Des Moines

Iowa Summer Weather Review

Temperatures:

Temperatures have remained warmer than normal for much of the spring into the first half of the summer.  The warm temperatures have been interrupted from time to time by cooler periods, especially in May when monthly temperatures averaged just below normal, but for the most part readings have remained warmer than normal.  The warmest readings have been across western Iowa with a couple periods of intense heat during June and July with heat index values going above 110 degrees during the third week of July.

 

Spring and early Summer temperature departure in Iowa – warmer than normal.

Spring and early Summer temperature departure in Iowa – warmer than normal.

Precipitation:

Since the beginning of March, precipitation has been most robust and reliable along the Minnesota border into east central Iowa as well as the far southwest corner of the state.  Much of the remainder of Iowa has seen at or below normal rainfall, especially in central into south central and southeast Iowa.  The month of June was particularly dry in these locations with some areas remaining below one inch of precipitation or only about a quarter of normal.  Recent storms across much of Iowa in July have helped to alleviate the incipient drought conditions in the state, although much of the rain was quickly used by maturing crops.  The map shows the percentage of normal precipitation from the March through July time frame.

Summer rainfall departures – Wet on the edges, dry central and southeast.

Summer rainfall departures – Wet on the edges, dry central and southeast.

Spring 2016 Climate Table
Blog post by Craig Cogil, Senior Forecaster, NWS Des Moines