| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -0.8° | -10° | 23.7mm | 6.6 | 17 |
| February | 1.8° | -8.3° | 33.4mm | 7.3 | 15 |
| March | 9.4° | -1.8° | 54mm | 9.1 | 42 |
| April | 16.7° | 4° | 89.1mm | 10.9 | 68 |
| May | 22.7° | 10.6° | 112.9mm | 12.8 | 74 |
| June | 28° | 16.3° | 119.3mm | 11.6 | 73 |
| July | 29.5° | 18.3° | 91.2mm | 9.1 | 72 |
| August | 28.6° | 17.1° | 91mm | 9.6 | 74 |
| September | 25.4° | 12.1° | 72.1mm | 8.8 | 82 |
| October | 17.7° | 5.2° | 75.8mm | 9 | 75 |
| November | 9.6° | -1.4° | 44.6mm | 7.6 | 46 |
| December | 2.2° | -6.9° | 36.4mm | 8.1 | 15 |
January in Iowa City averages a daily high of -0.8°C with nights around -10°C. Expect roughly 6.6 wet days totalling 23.7mm. A hard month to visit for comfort alone.
February in Iowa City averages a daily high of 1.8°C with nights around -8.3°C. Expect roughly 7.3 wet days totalling 33.4mm. A hard month to visit for comfort alone.
March in Iowa City averages a daily high of 9.4°C with nights around -1.8°C. Expect roughly 9.1 wet days totalling 54mm. Demanding conditions — pack for it and plan indoor options.
April in Iowa City averages a daily high of 16.7°C with nights around 4°C. Expect roughly 10.9 wet days totalling 89.1mm. Generally workable, with some weather to plan around.
May in Iowa City averages a daily high of 22.7°C with nights around 10.6°C. Expect roughly 12.8 wet days totalling 112.9mm. Generally workable, with some weather to plan around.
June in Iowa City averages a daily high of 28°C with nights around 16.3°C. Expect roughly 11.6 wet days totalling 119.3mm. Generally workable, with some weather to plan around.
July in Iowa City averages a daily high of 29.5°C with nights around 18.3°C. Expect roughly 9.1 wet days totalling 91.2mm. Generally workable, with some weather to plan around.
August in Iowa City averages a daily high of 28.6°C with nights around 17.1°C. Expect roughly 9.6 wet days totalling 91mm. Generally workable, with some weather to plan around.
September in Iowa City averages a daily high of 25.4°C with nights around 12.1°C. Expect roughly 8.8 wet days totalling 72.1mm. Comfortable conditions for being outdoors all day.
October in Iowa City averages a daily high of 17.7°C with nights around 5.2°C. Expect roughly 9 wet days totalling 75.8mm. Comfortable conditions for being outdoors all day.
November in Iowa City averages a daily high of 9.6°C with nights around -1.4°C. Expect roughly 7.6 wet days totalling 44.6mm. Demanding conditions — pack for it and plan indoor options.
December in Iowa City averages a daily high of 2.2°C with nights around -6.9°C. Expect roughly 8.1 wet days totalling 36.4mm. A hard month to visit for comfort alone.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Iowa City peaks at 82.
Based on 30 years of records, August–October scores highest for comfort in Iowa City, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 29.5°C.
June is the wettest, averaging 119.3mm of rain across roughly 11.6 wet days.
January is the coolest month, with average daily highs around -0.8°C.