Iowa Power Outage Season
When outages happen most in Iowa, and what to expect.
June is historically Iowa's busiest month for recorded power outages, part of a summer season (June–August) that accounts for about 35% of all recorded outages statewide, averaging 2.5 hours per event. 6 of Iowa's 99 tracked counties currently carry a Reliability Grade of F.
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Iowa outages by month
Total recorded events and average duration per event, summed across every tracked county in Iowa.
Peak season insight
Iowa's outage season runs June–August, accounting for 35% of all recorded outages. June has the highest frequency.
Month-by-month data table
| Month | Events | Avg duration |
|---|---|---|
| January | 1,774 | 1.9 hrs |
| February | 1,581 | 2.0 hrs |
| March | 2,516 | 3.0 hrs |
| April | 2,788 | 2.4 hrs |
| May | 3,526 | 2.5 hrs |
| June | 4,434 | 2.3 hrs |
| July | 4,277 | 2.7 hrs |
| August | 3,675 | 3.6 hrs |
| September | 2,986 | 1.9 hrs |
| October | 2,890 | 1.9 hrs |
| November | 2,406 | 1.9 hrs |
| December | 2,076 | 3.3 hrs |
This month in Iowa
October has historically recorded 2,890 outage events across Iowa, below the state's typical monthly average. Outages that start in October have averaged 1.9 hours.
Main causes by season
Named storms behind Iowa's worst recorded outages, from the NOAA Storm Events Database.
Winter (December–February)
- Blizzard
- Tornado
- Winter Weather
- Thunderstorm Wind
- High Wind
Spring (March–May)
- Thunderstorm Wind
- Drought
- Hail
- Tornado
- Blizzard
Summer (June–August)
- Hail
- Thunderstorm Wind
- Tornado
- Excessive Heat
- Flood
Fall (September–November)
- Drought
- Frost/Freeze
- Flash Flood
- Heavy Rain
- Hail
Iowa's worst outage events on record
The five largest outages in Iowa by duration and customers affected.
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Aug 10, 2020 | 211 hrs | 109,389 (69%) | Thunderstorm Wind |
| Aug 10, 2020 | 145 hrs | 114,873 (40%) | Drought |
| Aug 10, 2020 | 175 hrs | 51,777 (51%) | Thunderstorm Wind |
| Aug 10, 2020 | 155 hrs | 56,299 (46%) | Thunderstorm Wind |
| Aug 10, 2020 | 213 hrs | 35,836 (57%) | Drought |
Highest-risk counties in Iowa
Lowest reliability percentile among Iowa's tracked counties.
| County | Grade | National percentile |
|---|---|---|
| Marshall County | F | 6th |
| Tama County | F | 12th |
| Jasper County | F | 14th |
| Poweshiek County | F | 15th |
| Linn County | F | 16th |
Live weather alerts for Iowa
Flood Warning
Flood Warning issued October 1 at 8:45AM CDT until October 3 at 6:20AM CDT by NWS Omaha/Valley NE
Read the official NWS alert →Flood Warning
Flood Warning issued October 1 at 8:45AM CDT until October 2 at 4:00PM CDT by NWS Omaha/Valley NE
Read the official NWS alert →Flood Watch
Flood Watch issued October 1 at 6:34AM CDT until October 2 at 1:00AM CDT by NWS Des Moines IA
Read the official NWS alert →Flood Warning
Flood Warning issued October 1 at 6:23AM CDT until October 3 at 10:00AM CDT by NWS Des Moines IA
Read the official NWS alert →Flood Warning
Flood Warning issued October 1 at 6:23AM CDT until October 2 at 7:00PM CDT by NWS Des Moines IA
Read the official NWS alert →These live alerts come from the National Weather Service. They are public-safety information, not an outage prediction.
Iowa power outage FAQ
When do power outages happen most in Iowa?
June is historically the busiest single month for recorded outages in Iowa, and Summer (June–August) accounts for about 35% of all recorded outages across the state.
How long do power outages in Iowa typically last?
Across Iowa's tracked counties, the average recorded outage lasts about 2.5 hours, though individual events -- especially named storms -- can run much longer.
Which counties in Iowa have the highest outage risk?
Marshall County, Tama County, Jasper County, Poweshiek County, Linn County currently rank lowest for reliability in Iowa. See each county's page for its full history.
Does this page predict a power outage in Iowa?
No. It describes patterns in recorded county-level outage history, not a guaranteed future event. Check the live National Weather Service alerts below for current conditions.
Prepare for Iowa's outage season
Sized for Iowa's recorded outage frequency and duration.
