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Mercer County, Illinois severe weather history spans 341 recorded events between 1952 and 2026. The dominant hazard is thunderstorm wind, accounting for 39.6% of all recorded events. It ranks #1,549 nationally and #54 in Illinois.
341
Recorded events
1
Direct deaths
6
Direct injuries
$34.7M
Property damage
The record
What the Mercer County, Illinois severe weather history record shows
Across the archive, Mercer County, Illinois severe weather history averages 4.6 recorded events a year. The busiest stretch on record is the 2000s, with 110 events logged in that decade alone. Roughly 53 events fall before 1990 and 288 from 1990 onward — a gap that reflects the expansion of NOAA reporting practice as much as the weather itself.
The deadliest hazard in the Mercer County, Illinois record is lightning, responsible for 1 direct deaths. The costliest is flash flood, with $15.3M in reported property damage. In total, 8 distinct hazard types appear in this county archive, each listed with its own dated record below.
By hazard type
Every hazard type recorded in Mercer County
| Hazard | Events | Deaths | Damage | Max | Span |
|---|---|---|---|---|---|
| Thunderstorm Wind | 135 | 0 | $10.6M | 78 | 1957–2026 |
| Hail | 96 | 0 | $2.8M | 2.5 | 1959–2026 |
| Tornado | 45 | 0 | $5.3M | F3 | 1952–2026 |
| Flood | 35 | 0 | $575K | 0 | 1998–2024 |
| Flash Flood | 13 | 0 | $15.3M | 7 | 1997–2025 |
| Funnel Cloud | 8 | 0 | $0 | 0 | 2000–2018 |
| Heavy Rain | 6 | 0 | $150K | 6 | 2003–2011 |
| Lightning | 3 | 1 | $45K | 0 | 1997–2006 |
Decade by decade
Mercer County, Illinois severe weather history by decade
Reporting practice changed over time — early decades are undercounted, not calmer.
Tornado tracks
Paths crossing this county
46 mapped tornado paths intersect this county: 43 touched down inside it and 3 crossed in from a neighbouring county. This comes from path geometry, not county-tagged reports.
| Date | Scale | Deaths | Injuries | Path length | Origin |
|---|---|---|---|---|---|
| 1978-08-15 | EF3 | 0 | 0 | 6.4 mi | Touched down here |
| 1974-06-14 | EF3 | 0 | 2 | 48.6 mi | Crossed in |
| 2015-05-24 | EF2 | 0 | 0 | 6.8 mi | Touched down here |
| 2006-04-13 | EF2 | 0 | 0 | 2.0 mi | Touched down here |
| 1998-06-18 | EF2 | 0 | 0 | 6.0 mi | Touched down here |
| 1974-04-13 | EF2 | 0 | 0 | 0.1 mi | Touched down here |
| 1973-04-21 | EF2 | 0 | 2 | 30.2 mi | Touched down here |
| 2025-06-03 | EF1 | 0 | 0 | 1.6 mi | Touched down here |
| 2025-06-03 | EF1 | 0 | 0 | 10.8 mi | Touched down here |
| 2025-06-03 | EF1 | 0 | 0 | 3.8 mi | Touched down here |
Significant events
Deadliest events on record in Mercer County
| Date | Type | Location | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Jun 6, 1997 | Lightning | ALEDO | 1 | 0 | $0 |
| Nov 30, 1991 | Thunderstorm Wind | 0 | 3 | $0 | |
| Jun 14, 1974 | Tornado | 0 | 1 | $0 | |
| Apr 14, 1974 | Tornado | 0 | 1 | $3K | |
| Apr 24, 1965 | Tornado | 0 | 1 | $250K |
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Numerous trees and power lines were downed in Joy. Westmer High School had considerable roof damage done to the gymnasium. The outer roof of the Frontier Communications Building was peeled off. A mobile home just north of Joy was destroyed.
The tornado damaged several rural home sites. Northeast of Seaton damage was noted to farm buildings and a silo. South of Aledo seven power lines poles were snapped, and a farmhouse 4 miles west of Aledo was destroyed. The tornado also damaged or destroyed farm buildings, roofs and chimneys south of Aledo.
Heavy rainfall of 4 to over 10 inches over significant areas from 21 to 23 September in extreme North Central and Northeast Iowa moved downstream causing the Mississippi River to rise above major flood stage levels. ||Keithsburg rose above its major flood stage level of 17.0 feet on September 30th, 2016 around 10 AM CST. It crested around 17.8 feet on October 2nd, 2016. It fell below major flood stage on October 4th around 4 AM CST.
Context
Risk, population and federal disasters
Very Low
FEMA NRI risk rating
15,495
Population (ACS)
$147K
Median home value
15
Federal declarations
| Declared | Incident | Title | Type |
|---|---|---|---|
| Mar 26, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Mar 13, 2020 | Biological | COVID-19 | EM |
| Sep 19, 2019 | Flood | SEVERE STORMS AND FLOODING | DR |
| May 10, 2013 | Flood | SEVERE STORMS, STRAIGHT-LINE WINDS, AND FLOODING | DR |
| Mar 17, 2011 | Snowstorm | SEVERE WINTER STORM AND SNOWSTORM | DR |
| Jun 24, 2008 | Severe Storm | SEVERE STORMS AND FLOODING | DR |
Quick answers
Frequently asked
How many severe weather events have been recorded in Mercer County, Illinois?
341 events are on record between 1952 and 2026, causing 1 direct deaths and $34.7M in property damage.
What is the most common severe weather hazard in Mercer County?
Thunderstorm Wind, with 135 recorded events — 39.6% of everything in the archive for this county.
How many tornadoes have crossed Mercer County?
46 mapped tornado paths intersect the county boundary; 43 of them touched down inside it. This is derived from path geometry, not county-tagged reports.
How many federal disaster declarations cover Mercer County?
15 federal disaster declarations from FEMA include Mercer County, each tied to a specific incident period.
How risky is Mercer County compared with the rest of the country?
FEMA's National Risk Index rates Mercer County as very low risk, placing it in the 9 percentile of its state for expected annual loss.
Where does the Mercer County, Illinois severe weather history data come from?
Every figure is drawn from United States federal public-domain records: NOAA/NCEI Storm Events for the event archive, NOAA SPC SVRGIS for mapped tornado paths, FEMA for disaster declarations and risk ratings, and the U.S. Census for population context. Dates are shown in UTC and recent entries may still be revised by NOAA.
Nearby
Neighbouring counties
- Menard County 258
- Monroe County 315
- Massac County 300
- Montgomery County 417
- Mason County 268
- Morgan County 371
Cite this page
“Mercer County, Illinois.” Severe Weather History. severeweatherhistory.com/county/illinois/mercer-county/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.