Portland receives its highest rainfall in Dec, while humidity peaks during summer months.
🌧️ Wettest:Dec — 124 mm☀️ Driest:Aug — 86 mm
💧 Humidity peaks at 87% in Jun · annual avg 84%
🌍 Climate Summary
Avg Annual Temp:46.9°F
Avg Annual Rainfall:1269 mm
Avg Humidity:84%
Data Period:1981 – 2025
Portland Climate Overview
Portland has a temperate climate with warm summers and freezing winters.
Temperatures peak in Aug and drop to their lowest in Jan,
while rainfall is highest during winter months.
Humidity remains high throughout the year creating cold and damp conditions.
📈 Yearly Trends
The warmest year in Portland's recorded history was 2010
(avg: 50°F),
while the coldest year was 1992
(avg: 44.1°F),
based on annual average temperatures.
📊 Key Climate Trends
🌡️ Portland's temperature has remained relatively stable over the past decade
📊 Minimum temperatures have remained largely stable across the dataset
🌧️ Rainfall has decreased in recent years compared to earlier periods
🌡️ Annual Temperature Trend
View Range:
Average annual high/low · Last 10 years · °F
Portland's temperatures has remained relatively stable over the past decade.
The highest recorded temperature reached
79.5°F in Aug 2010,
while the lowest dropped to
-5.5°F in Feb 2023.
🌧️ Annual Precipitation
View Range:
Total annual precipitation · Last 10 years · mm/year
Annual rainfall in Portland shows noticeable variation. Rainfall has decreased in recent years compared to earlier periods.
Based on 45 years of data (1981–2025), Aug is typically the hottest month in Portland, Maine, with average high temperatures around 75.2°F.
What is the coldest month in Portland?▼
Jan is the coldest month in Portland, with average low temperatures around 8.5°F.
What is the rainiest month in Portland?▼
Dec receives the most rainfall with approximately 124 mm, while Aug is the driest with 86 mm.
What was the highest temperature ever recorded in Portland?▼
The highest recorded temperature was 79.5°F in Aug 2010. This is part of the historical record spanning 1981–2025.
What was the lowest temperature ever recorded in Portland?▼
The lowest recorded temperature was -5.5°F in Feb 2023.
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 Portland get?▼
Portland receives the most sunlight in Jul with an average solar radiation of 5.79 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning, agriculture, and understanding seasonal sunshine availability in Maine.
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.