Waukegan has a temperate climate with warm summers and freezing winters.
Temperatures peak in August and drop to their lowest in January, while rainfall is highest during summer months.
Humidity remains high throughout the year, especially during winter months, creating cold and damp conditions.
| Month | 🌤️ | High | Low | Avg | Humid % | Rain (mm) | Wind (m/s) | Solar (kWh/m²) |
|---|---|---|---|---|---|---|---|---|
| January | ❄️ | 43.8°F | -11.8°F | 16.0°F | 89% | 41 | 4.3 | 1.44 |
| February | ❄️ | 51.0°F | -5.4°F | 22.8°F | 85% | 41 | 4.3 | 2.32 |
| March | 🌨️ | 66.2°F | 10.2°F | 38.2°F | 79% | 61 | 4.1 | 3.49 |
| April | ☔ | 75.0°F | 23.7°F | 49.4°F | 77% | 90 | 4.0 | 4.45 |
| May | ☔ | 81.4°F | 33.9°F | 57.6°F | 76% | 101 | 3.4 | 5.27 |
| June | ☔ | 87.8°F | 44.2°F | 66.0°F | 75% | 109 | 2.9 | 5.85 |
| July | ☔ | 90.7°F | 53.5°F | 72.1°F | 74% | 103 | 2.6 | 5.85 |
| August | ☔ | 91.6°F | 52.9°F | 72.2°F | 73% | 106 | 2.5 | 5.14 |
| September | ☔ | 87.5°F | 40.7°F | 64.1°F | 73% | 87 | 2.9 | 4.08 |
| October | 🌤️ | 77.9°F | 27.8°F | 52.8°F | 76% | 77 | 3.5 | 2.72 |
| November | 🌨️ | 64.2°F | 15.2°F | 39.7°F | 81% | 63 | 3.8 | 1.69 |
| December | ❄️ | 49.4°F | -2.5°F | 23.5°F | 88% | 52 | 3.9 | 1.23 |
Showing average climate conditions across 45 years (1981–2025)
🧥 Pack heavy layers and prepare for snow — this is a Severe Winter destination.
🌤️ Early mornings and evenings are most comfortable during this Hot Summer season.
☔ Moderate Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025 climate normals · °F
Temperatures rise steadily from spring, peak in August, and gradually decline through autumn into winter.
These seasonal patterns make summer ideal for outdoor activities, while winters bring freezing conditions and heavy snowfall.
Monthly rainfall · 1981–2025 seasonal trends · mm/month
Rainfall is concentrated in the summer months. Humidity stays high (around 79%), peaking during winter months, which creates cold and damp conditions.
☔ Moderate Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025
Across 45 years of records, Waukegan's temperature shows a slight warming trend over the past decade. Its hottest day reached 103.7°F in July 2012, and its coldest dropped to -36.9°F in January 1982. 2012 was the warmest year overall and 2014 the coolest.
The warmest year in Waukegan's recorded history was 2012 (avg: 53.2°F), while the coldest was 2014 (avg: 43.2°F).
Average annual high/low · Last 30 years · °F
Total annual precipitation · Last 30 years · mm/year
| Year | Min Temp | Avg Temp | Max Temp | Rainfall (mm) | Avg Humidity | Avg Wind |
|---|---|---|---|---|---|---|
2025 | 23.2°F | 49.3°F | 75.4°F | 837 | 76% | 3.5 m/s |
2024 | 27.1°F | 51.1°F | 74.8°F | 974 | 76% | 3.4 m/s |
2023 | 25.3°F | 50.4°F | 75.4°F | 866 | 76% | 3.3 m/s |
2022 | 23.2°F | 48.2°F | 73.2°F | 935 | 77% | 3.7 m/s |
2021 | 27.1°F | 50.7°F | 74.3°F | 662 | 76% | 3.4 m/s |
2020 | 27.1°F | 49.1°F | 70.9°F | 1033 | 81% | 3.4 m/s |
2019 | 19.9°F | 44.6°F | 69.3°F | 1219 | 85% | 3.4 m/s |
2018 🌧️ | 24.8°F | 48.2°F | 71.4°F | 1228 | 82% | 3.3 m/s |
2017 | 25.5°F | 49.6°F | 73.9°F | 1076 | 79% | 3.5 m/s |
2016 | 24.6°F | 49.1°F | 73.4°F | 890 | 81% | 3.4 m/s |
Showing 1 to 10 of 45 years
Based on 45 years of data (1981–2025), August is typically the hottest month in Waukegan, Illinois, with average high temperatures around 91.6°F.
January is the coldest month in Waukegan, with average low temperatures around -11.8°F.
June receives the most rainfall with approximately 109 mm, while February is the driest with 41 mm.
The highest recorded temperature was 103.7°F in July 2012. This is part of the historical record spanning 1981–2025.
The lowest recorded temperature was -36.9°F in January 1982.
This page covers 45 years of climate data from 1981 to 2025. As new data is added to the database the page automatically reflects the updated coverage.
Waukegan receives the most sunlight in July with an average solar radiation of 5.85 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning and agriculture in Illinois.
All climate data is sourced from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite and model data. It provides monthly averages for temperature, precipitation, humidity, wind speed, and solar radiation.
All weather data is sourced from NASA POWER (Prediction of Worldwide Energy Resources), a NASA project providing solar and meteorological data for renewable energy, building efficiency, and agricultural research.
