Squirrels in Illinois in September
Yes, September is one of the best months to see squirrels in Illinois. It is the 3rd busiest month of the year, with 2,501 of the 24,549 sightings logged across the year (10.2%), based on verified iNaturalist records.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 28, 2026.
Peak month for squirrels in Illinois
10.2%
of yearly sightings
2,501
records in September
#3
busiest month of 12
24,549
verified records a year
August 6.2%, September 10.2%, October 9.8%. Busiest month is April at 14.8%.
24,549 verified observations of squirrels in Illinois, recorded across 12 months of the year on iNaturalist.
When squirrels are recorded in Illinois
Peak month
April
3,644 records (14.8% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 1,299 | 5.3% |
| February | 1,309 | 5.3% |
| March | 2,290 | 9.3% |
| Aprilpeak | 3,644 | 14.8% |
| Maypeak | 3,136 | 12.8% |
| June | 2,094 | 8.5% |
| July | 1,284 | 5.2% |
| August | 1,534 | 6.2% |
| Septemberpeak | 2,501 | 10.2% |
| October | 2,416 | 9.8% |
| November | 1,750 | 7.1% |
| December | 1,292 | 5.3% |
Squirrels you are most likely to see
| Species | Verified observations |
|---|---|
| Eastern Gray Squirrel | 13,881 |
| Eastern Chipmunk | 4,523 |
| Eastern Fox Squirrel | 3,453 |
| Groundhog | 1,523 |
| Thirteen-lined Ground Squirrel | 510 |
| Southern Flying Squirrel | 177 |
| American Red Squirrel | 81 |
| Franklin's Ground Squirrel | 5 |
In Illinois, September carries 10.2% of the year's squirrels sightings, about 1.9 points above an even month-to-month split. That makes it the 3rd busiest of the twelve months, out of 12 months with recorded activity.
Activity is rising from August (6.2%) into September, and it heads toward October (9.8%) after. This is right inside the peak window, so September is one of the surest months to plan a trip around.
The squirrels most often recorded in Illinois are Eastern Gray Squirrel, Eastern Chipmunk and Eastern Fox Squirrel. Those counts are annual totals rather than a September split, so treat them as which species you are likely to encounter, while the month figures above show how many sightings fall in September itself.
Which squirrels you are most likely to see
- Eastern Gray Squirrel13,881 records
- Eastern Chipmunk4,523 records
- Eastern Fox Squirrel3,453 records
- Groundhog1,523 records
- Thirteen-lined Ground Squirrel510 records
- Southern Flying Squirrel177 records
Plan your squirrel trip in Illinois
Start with live tours near Lewis & Clark National Historic Trail, then compare a nearby stay and a broader wildlife backup before you lock in the trip.
GetYourGuide
Live tours nearbySee live tours near Lewis & Clark National Historic Trail
Use the live GetYourGuide widget to compare local departures and activity styles close to the main squirrel viewing area.
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Stay nearbyStay near Lewis & Clark National Historic Trail
Compare hotels, cabins and lodges close to the best squirrel viewing area in Illinois.
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Broader backupBook a squirrel tour in Illinois
Compare guided wildlife tours, boat trips and nature experiences if you want a second travel network beyond the live widget.
Gear to see them
Frequently asked questions
Can you see squirrels in Illinois in September?+
Yes. September accounts for 2,501 of the 24,549 verified squirrels sightings logged in Illinois across the year, which is 10.2% of the annual total.
Is September a good time to see squirrels in Illinois?+
September is one of the best months. It ranks 3rd of the year and sits inside the peak window of April, May and September.
What month is best for squirrels in Illinois?+
April is the single busiest month, with the broader peak running through April, May and September, based on 24,549 verified observations.
Which squirrels are you most likely to see in Illinois?+
The most-recorded species in Illinois are Eastern Gray Squirrel, Eastern Chipmunk and Eastern Fox Squirrel, based on all-time iNaturalist counts.