Boston is 1.9°C (3.4°F) warmer by day, Chicago has 2.1°C (3.8°F) warmer nights, Boston gets 246 mm (9.7 in) more rain a year.
Boston is at its warmest in July and coolest in January, while Chicago peaks in August and bottoms out in January. Month for month, Chicago is the warmer of the two in 8 of 12 months.
Boston is the wetter of the two, collecting 1,213 mm (47.8 in) of rain a year against 967 mm (38.1 in) in Chicago. The most comfortable time to visit is June, July and August in Boston and July, August and September in Chicago.
| Boston | Metric | Chicago |
|---|---|---|
| 🌡️ Temperature | ||
| 57.4°F | 🌡️Average daytime high | 54°F |
| 40.1°F | 🌙Average nighttime low | 43.9°F |
| July | 🔥Hottest month | August |
| January | ❄️Coldest month | January |
| 🌧️ Rain | ||
| 47.8 in | 🌧️Annual rainfall | 38.1 in |
| October | ☔Wettest month | May |
| February | 🏜️Driest month | January |
| 💨 Climate | ||
| 80% | 💧Average humidity | 81% |
| 0.7 m/s | 💨Average wind speed | 4.4 m/s |
Overnight, Boston typically falls to around 4.5°C (40.1°F) while Chicago settles near 6.6°C (43.9°F).
Boston is hottest in July and coldest in January, whereas Chicago peaks in August and is coolest in January.
Boston sees the most rain in October and the least in February; Chicago is wettest in May and driest in January.
Chicago feels the more humid of the two, averaging 81% relative humidity against 80%.
For Chicago, the pick of the year is July, August and September.
Month by month, here is the coldest night, the average day and the hottest afternoon each city can expect. Switch Compare to read rainfall, humidity, wind or solar instead, and Period to move between the long-term 45-year average and any single year — the shading is a quick warm-to-cool guide.
| Month | Boston | Chicago | ||||
|---|---|---|---|---|---|---|
| Min | Avg | Max | Min | Avg | Max | |
| January | 17.8 | 25❄️ | 32.4 | 22.1 | 26.6❄️ | 31.1 |
| February | 19.4 | 27.1 | 34.9 | 23.7 | 28.4 | 33.1 |
| March | 26.4 | 34.7 | 43 | 30.9 | 36 | 41 |
| April | 35.8 | 45.1 | 54.5 | 38.5 | 44.1 | 49.6 |
| May | 46.4 | 55.9 | 65.5 | 47.1 | 52.9 | 58.6 |
| June | 55.9 | 65.1 | 74.3 | 57.9 | 63.5 | 69.1 |
| July | 62.4 | 71.8🔥 | 81.1 | 66.2 | 71.1 | 75.9 |
| August | 61.3 | 71.1 | 80.8 | 66.6 | 71.4🔥 | 76.1 |
| September | 54.1 | 64 | 73.8 | 60.1 | 65.3 | 70.5 |
| October | 43.7 | 52.5 | 61.5 | 48.7 | 54 | 59.2 |
| November | 33.8 | 41.5 | 49.3 | 37.4 | 42.1 | 46.6 |
| December | 24.8 | 31.5 | 38.1 | 27.7 | 31.6 | 35.8 |
| Annual Avg | 40.1 | 48.7 | 57.4 | 43.9 | 48.9 | 54 |
Min / mean / max temperature (°F). 🔥 marks each city's hottest month, ❄️ its coldest; shading runs cool blue to warm red.
The same figures plotted out, so the shape of a typical year is easier to see than in a grid. Where the two lines run close together Boston and Chicago feel alike; where they separate, they are genuinely different places to be.
Hover or tap any point to read the exact figures. Boston Chicago
See how Boston and Chicago stack up against other cities. Swipe for more.
Choose which city to keep, then search for any other city in our database — we'll build the comparison for you.
Quick answers to the questions people ask most when comparing Boston and Chicago — each drawn straight from the climate figures above.
Boston is the warmer of the two. It averages daytime highs of 14.1°C (57.4°F) against 12.2°C (54°F) in Chicago — roughly 1.9°C (3.4°F) warmer by day. Nights are milder in Chicago, with average lows of 6.6°C (43.9°F) versus 4.5°C (40.1°F).
Boston is hottest in July, averaging highs of about 27.3°C (81.1°F), while Chicago peaks in August at around 24.5°C (76.1°F). That makes Boston the hotter of the two at the height of summer.
Boston gets colder. In its coldest month (January) overnight lows average about -7.9°C (17.7°F), compared with -5.5°C (22.2°F) at the low point of the year in Chicago.
Boston is the wetter city, collecting about 1,213 mm (47.8 in) of rain a year versus 967 mm (38.1 in) in Chicago. Boston is wettest in October and driest in February; Chicago is wettest in May and driest in January.
Humidity is similar in both, averaging around 80% in Boston and 81% in Chicago across the year.
The most comfortable months in Boston are June, July and August, when average temperatures are at their mildest.
Chicago is at its most pleasant around July, August and September, based on the mildest average temperatures of the year.
Chicago is the warmer city in 8 of the 12 months of the year. The gap is widest in May, about 1.7°C (3.1°F), and narrowest in December, about 0.1°C (0.2°F).
Boston has the bigger seasonal swing, about 26°C (46.8°F) between its coldest and hottest months versus 24.9°C (44.8°F) in Chicago — so Chicago has the steadier, more even climate.
It depends what matters most to you: choose Boston for warmer weather and pick Chicago if you prefer drier conditions. There is no single "better" climate — it comes down to whether you value warmth, dryness or comfort most.
Every figure on this page is calculated from NASA POWER satellite climate data spanning 1981–2025 (45 years). The averages describe the long-term climate of Boston and Chicago, not a single year's weather or a short-range forecast.
