Best Time to See Frogs in Illinois
May, June and April is the best time to see frogs in Illinois. Based on 29,185 verified iNaturalist observations, here is exactly when frogs are most active across the year in Illinois.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 28, 2026.
Green Frog · psweet CC BY-SA
American Bullfrog · L.J. Lamera CC BY
Blanchard's Cricket Frog · Bryant Brumbill-Corral CC BY
29,185 verified observations of frogs in Illinois, recorded across 12 months of the year on iNaturalist.
When frogs are recorded in Illinois
Peak month
May
5,342 records (18.3% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 53 | 0.2% |
| February | 303 | 1% |
| March | 1,803 | 6.2% |
| Aprilpeak | 4,421 | 15.1% |
| Maypeak | 5,342 | 18.3% |
| Junepeak | 4,584 | 15.7% |
| July | 3,599 | 12.3% |
| August | 3,247 | 11.1% |
| September | 3,133 | 10.7% |
| October | 2,366 | 8.1% |
| November | 258 | 0.9% |
| December | 76 | 0.3% |
Frogs you are most likely to see
| Species | Verified observations |
|---|---|
| American Toad | 6,738 |
| American Bullfrog | 4,770 |
| Green Frog | 2,562 |
| Blanchard's Cricket Frog | 2,560 |
| Northern Leopard Frog | 1,676 |
| Fowler's Toad | 1,318 |
| Southern Leopard Frog | 1,237 |
| Gray Treefrog | 1,134 |
Weather to expect, source Open-Meteo
Typical weather in Illinois
Recent typical conditions by month, so you can plan a trip around both when frogs are active and what the weather is doing. The best months to look for frogs sit around 43 to 83 degrees Fahrenheit, so pack for that.
| Month | Avg high | Avg low | Rain |
|---|---|---|---|
| Jan | 38°F | 23°F | 3" |
| Feb | 40°F | 22°F | 3.1" |
| Mar | 53°F | 34°F | 4.8" |
| Aprbest time | 63°F | 43°F | 4.1" |
| Maybest time | 73°F | 54°F | 4.6" |
| Junbest time | 83°F | 64°F | 3.5" |
| Jul | 85°F | 68°F | 4.3" |
| Aug | 83°F | 66°F | 3.9" |
| Sep | 79°F | 61°F | 3" |
| Oct | 65°F | 48°F | 4.9" |
| Nov | 52°F | 35°F | 1.8" |
| Dec | 45°F | 29°F | 2.3" |
Typical recent conditions (5-year means) from the Open-Meteo archive, averaged for Illinois. Weather varies year to year, so treat these as a guide.
More on frogs in Illinois:
Sightings of frogs in Illinois peak in May, when 5,342 of the year's 29,185 verified observations are logged — about 18.3% of the annual total. Activity stays high through May, June and April.
The quietest stretch is January and December, when frogs are hardest to find — January sees just 53 records. If a reliable sighting matters, plan around the peak window rather than the off-season.
The frogs you are most likely to encounter in Illinois are American Toad, American Bullfrog and Green Frog — the most-recorded species in the state. Each keeps its own seasonal rhythm, but the month-by-month pattern above reflects every reported sighting together.
Where to go
Best places to see frogs in Illinois
- Lewis & Clark National Historic Trail — National Historic Trail
- Lincoln Home National Historic Site — National Historic Site
- Emmett Till and Mamie Till-Mobley National Monument — National Monument
- Mormon Pioneer National Historic Trail — National Historic Trail
- New Philadelphia National Historic Site — National Historic Site
- Pullman National Historical Park — National Historical Park
Gear to see them
Frequently asked questions
What is the best month to see frogs in Illinois?+
May is the single best month, and the broader peak window runs through May, June and April, based on 29,185 verified iNaturalist observations.
When are frogs hardest to see in Illinois?+
January is the quietest month for frogs in Illinois, with only 53 verified records.
Are frogs active year-round in Illinois?+
Frogs are recorded in 12 of 12 months in Illinois, so they can be seen year-round, with a clear peak in May.
More places to see frogs
More wildlife in Illinois