Oak Brook (IL) Temperature by Month
Oak Brook in Illinois, United States of America sees significant seasonal temperature differences, with daytime highs between 0°C (32°F) in January and 29°C (84°F) in July, averaging 15°C (59°F) annually. Explore the full monthly breakdown below.
Oak Brook Monthly Temperatures
In Oak Brook, temperatures differ significantly between summer and winter months. Nighttime lows reflect this range, dropping from 18°C (64°F) in July to -9°C (16°F) in January.
The chart below illustrates the average maximum day and minimum night temperatures in Oak Brook by month:
The coolest part of the day is typically between 4 AM and 6 AM, while 3 PM is usually the warmest, when solar heating is at its peak. July, the city's warmest month, averages 319 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Oak Brook vs the United States of America
The map below shows the annual temperature across the United States of America. You can also select individual months if you want to compare a specific time of year.
very warm
warm
pleasant
moderate
cold
very cold
Oak Brook vs World: Temperature Compared
Oak Brook's average annual maximum temperature is 15°C (59°F). To put that in context, here's how it compares to a few well-known destinations:
Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.
Zermatt, Switzerland averages just 4°C (39°F) annually due to its altitude, with very cold winters and cool summers even at its warmest.
Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.
Perth, Australia averages 25°C (77°F) annually, with a classic Mediterranean climate — hot dry summers and mild wet winters.
What Does the Temperature Feel Like in Oak Brook?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.
In Oak Brook, January is the coolest month, with average highs of 0°C (32°F) and humidity around 72% — considered high. In July, the warmest month, temperatures average 29°C (84°F) with 68% humidity — conditions that feel high. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
Seasonal temperature shifts influence more than just how warm it feels — they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.
Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Oak Brook this rarely lasts long on the ground.
For more on Oak Brook's weather — including monthly rainfall, sunshine hours, and humidity — visit our Oak Brook climate page.
