Weather in Joliet, Illinois
Roses open along the stoops. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 16Light Drizzle50%83°62°
- SundayMay 17Overcast19%86°63°
- MondayMay 18Rain61%82°68°
- TuesdayMay 19Showers68%77°57°
- WednesdayMay 20Overcast39%65°48°
- ThursdayMay 21Overcast—66°47°
- FridayMay 22Overcast—57°53°
- PM 2.5
- 6.1 μg/m³
- PM 10
- 7.0 μg/m³
- NO₂
- 11.7 μg/m³
- Ozone
- 86.0 μg/m³
- UV Index
- 0.0 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 10:36 AM
- Moonset
- 1:37 AM
- In sign
- ♊︎ Gemini
Roses open along the stoops
Joliet at a glance
- Today vs. normal: 70°F — typical for the season
- Last frost: April 25 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Warm-season window is open
As of May 17, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
July brings Joliet's warmest temperatures (~74°F mean) while January delivers the coldest (~24°F). Rainfall peaks in July (4.5 inches) and drops to its lowest point in February (1.8 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 24° | 2.0″ | 5 |
| February | 28° | 1.8″ | 5 |
| March | 38° | 2.3″ | 5 |
| April | 49° | 3.9″ | 7 |
| May | 60° | 4.5″ | 8 |
| June | 70° | 4.3″ | 7 |
| July | 74° | 4.5″ | 6 |
| August | 72° | 4.0″ | 6 |
| September | 66° | 3.2″ | 5 |
| October | 53° | 3.1″ | 6 |
| November | 40° | 2.5″ | 5 |
| December | 29° | 1.9″ | 5 |
Regional context
Joliet belongs to a warm-summer humid continental climate region — sharing similar temperature ranges, seasonal patterns, and growing conditions with nearby cities in this climate group.
Similar climates: Chicago, IL, Rockford, IL, Round Lake Beach, IL, Aurora, IL, Naperville, IL.
Naturalist notes
Late April brings the first migrating warblers through Joliet's woodlands as oak trees begin leafing out.
May nights fill with the territorial calls of American toads as lilac bushes reach peak bloom across the city.
Frequently asked
- When does it freeze in Joliet?
- Joliet's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Joliet?
- July is the wettest month with about 4.5 inches of rain on average; the city receives roughly 38 inches annually.
- What is the warmest month in Joliet?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in Joliet?
- January is typically coldest, averaging about 24°F.
- When can I start a vegetable garden in Joliet?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Joliet get?
- Joliet averages about 70 rainy days per year.
- What hardiness zone is Joliet?
- Joliet's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Joliet, Illinois sits in a warm-summer humid continental climate zone. January temperatures hover near 24°F while July averages 74°F — a 50°F seasonal swing.
Throughout the year, Joliet receives about 38 inches of precipitation spread over roughly 70 rainy days.
Latitude (41.5°N), proximity to large water bodies, and elevation set the rhythm of the year — shaping what grows here, when frost is likely, and what the weather story looks like day to day.