Waterloo receives its highest rainfall in Jun, while humidity peaks during winter months.
🌧️ Wettest:Jun — 133 mm☀️ Driest:Jan — 26 mm
💧 Humidity peaks at 88% in Jan · annual avg 77%
🌍 Climate Summary
Avg Annual Temp:47.5°F
Avg Annual Rainfall:910 mm
Avg Humidity:77%
Data Period:1981 – 2025
Waterloo Climate Overview
Waterloo has a temperate climate with warm summers and freezing winters.
Temperatures peak in Jul and drop to their lowest in Jan,
while rainfall is highest during summer months.
Humidity remains high throughout the year, especially during winter months, creating cold and damp conditions.
📈 Yearly Trends
The warmest year in Waterloo's recorded history was 2012
(avg: 53.1°F),
while the coldest year was 1993
(avg: 43°F),
based on annual average temperatures.
📊 Key Climate Trends
🌡️ Waterloo's temperature shows a slight warming trend over the past decade
📈 Minimum temperatures show a slight warming trend in recent years
🌧️ Rainfall has decreased in recent years compared to earlier periods
🌡️ Annual Temperature Trend
View Range:
Average annual high/low · Last 10 years · °F
Waterloo's temperatures shows a slight warming trend over the past decade.
The highest recorded temperature reached
107.2°F in Jul 2012,
while the lowest dropped to
-43.5°F in Feb 1996.
🌧️ Annual Precipitation
View Range:
Total annual precipitation · Last 10 years · mm/year
Annual rainfall in Waterloo shows noticeable variation. Rainfall has decreased in recent years compared to earlier periods.
Based on 45 years of data (1981–2025), Jul is typically the hottest month in Waterloo, Iowa, with average high temperatures around 92.1°F.
What is the coldest month in Waterloo?▼
Jan is the coldest month in Waterloo, with average low temperatures around -14.2°F.
What is the rainiest month in Waterloo?▼
Jun receives the most rainfall with approximately 133 mm, while Jan is the driest with 26 mm.
What was the highest temperature ever recorded in Waterloo?▼
The highest recorded temperature was 107.2°F in Jul 2012. This is part of the historical record spanning 1981–2025.
What was the lowest temperature ever recorded in Waterloo?▼
The lowest recorded temperature was -43.5°F in Feb 1996.
How many years of data does this page cover?▼
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.
How much sunlight does Waterloo get?▼
Waterloo receives the most sunlight in Jul with an average solar radiation of 6.23 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning, agriculture, and understanding seasonal sunshine availability in Iowa.
Where does this weather data come from?▼
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.
📚 Data Source
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.