Best Time to See Tree Frogs in Illinois
April, May and October is the best time to see tree frogs in Illinois. Based on 8,972 verified iNaturalist observations, here is exactly when tree 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.
Blanchard's Cricket Frog · Bryant Brumbill-Corral CC BY
Spring Peeper · John G. Phillips CC BY
Spring Peeper · Madison Emmerich CC BY
8,972 verified observations of tree frogs in Illinois, recorded across 12 months of the year on iNaturalist.
When tree frogs are recorded in Illinois
Peak month
April
1,636 records (18.2% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 17 | 0.2% |
| February | 137 | 1.5% |
| March | 951 | 10.6% |
| Aprilpeak | 1,636 | 18.2% |
| Maypeak | 1,321 | 14.7% |
| June | 944 | 10.5% |
| July | 805 | 9% |
| August | 862 | 9.6% |
| September | 937 | 10.4% |
| Octoberpeak | 1,232 | 13.7% |
| November | 111 | 1.2% |
| December | 19 | 0.2% |
Tree Frogs you are most likely to see
| Species | Verified observations |
|---|---|
| Blanchard's Cricket Frog | 2,560 |
| Gray Treefrog | 1,132 |
| Boreal Chorus Frog | 1,103 |
| Spring Peeper | 679 |
| Green Treefrog | 659 |
| Cope's Gray Tree Frog | 502 |
| Bird-voiced Treefrog | 195 |
| Western Chorus Frog | 102 |
Weather to expect, source Open-Meteo
Typical weather in Illinois
Recent typical conditions by month, so you can plan a trip around both when tree frogs are active and what the weather is doing. The best months to look for tree frogs sit around 43 to 73 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" |
| Jun | 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" |
| Octbest time | 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 tree frogs in Illinois:
Sightings of tree frogs in Illinois peak in April, when 1,636 of the year's 8,972 verified observations are logged — about 18.2% of the annual total. Activity stays high through April, May and October.
The quietest stretch is January and December, when tree frogs are hardest to find — January sees just 17 records. If a reliable sighting matters, plan around the peak window rather than the off-season.
The tree frogs you are most likely to encounter in Illinois are Blanchard's Cricket Frog, Gray Treefrog and Boreal Chorus 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 tree 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
Frequently asked questions
What is the best month to see tree frogs in Illinois?+
April is the single best month, and the broader peak window runs through April, May and October, based on 8,972 verified iNaturalist observations.
When are tree frogs hardest to see in Illinois?+
January is the quietest month for tree frogs in Illinois, with only 17 verified records.
Are tree frogs active year-round in Illinois?+
Tree frogs are recorded in 12 of 12 months in Illinois, so they can be seen year-round, with a clear peak in April.
More places to see tree frogs
More wildlife in Illinois