Portland has a temperate climate with warm summers and freezing winters.
Temperatures peak in August and drop to their lowest in January, while rainfall is highest during winter months.
Humidity remains high throughout the year creating cold and damp conditions.
| Month | 🌤️ | High | Low | Avg | Humid % | Rain (mm) | Wind (m/s) | Solar (kWh/m²) |
|---|---|---|---|---|---|---|---|---|
| January | ☔ | 46.8°F | 8.5°F | 27.6°F | 86% | 104 | 5.2 | 1.63 |
| February | ☔ | 44.4°F | 11.0°F | 27.7°F | 84% | 92 | 5.1 | 2.52 |
| March | ☔ | 48.6°F | 15.9°F | 32.2°F | 82% | 114 | 4.6 | 3.65 |
| April | ☔ | 55.7°F | 30.5°F | 43.1°F | 84% | 116 | 3.6 | 4.63 |
| May | ☔ | 64.5°F | 40.0°F | 52.2°F | 86% | 98 | 2.9 | 5.31 |
| June | ☔ | 70.5°F | 48.5°F | 59.5°F | 87% | 104 | 2.6 | 5.66 |
| July | ☔ | 74.8°F | 56.8°F | 65.8°F | 87% | 93 | 2.4 | 5.79 |
| August | ☔ | 75.2°F | 56.7°F | 66.0°F | 85% | 86 | 2.5 | 5.23 |
| September | ☔ | 71.8°F | 49.2°F | 60.5°F | 83% | 94 | 3.0 | 4.19 |
| October | ☔ | 64.2°F | 39.2°F | 51.7°F | 80% | 124 | 3.9 | 2.83 |
| November | ☔ | 57.2°F | 28.5°F | 42.8°F | 80% | 122 | 4.6 | 1.85 |
| December | ☔ | 51.1°F | 15.3°F | 33.2°F | 83% | 124 | 4.9 | 1.38 |
Showing average climate conditions across 45 years (1981–2025)
🧥 Pack heavy layers and prepare for snow — this is a Severe Winter destination.
🌤️ Conditions are ideal for outdoor activities throughout the day in this Mild Summer.
☔ Moderate Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025 climate normals · °F
Temperatures rise steadily from spring, peak in August, and gradually decline through autumn into winter.
These seasonal patterns make summer ideal for outdoor activities, while winters bring freezing conditions and heavy snowfall.
Monthly rainfall · 1981–2025 seasonal trends · mm/month
Rainfall is concentrated in the winter months. Humidity stays high (around 84%), peaking during summer months, which creates cold and damp conditions.
☔ Moderate Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025
Across 45 years of records, Portland's temperature has remained relatively stable over the past decade. Its hottest day reached 79.5°F in August 2010, and its coldest dropped to -5.5°F in February 2023. 2010 was the warmest year overall and 1992 the coolest.
The warmest year in Portland's recorded history was 2010 (avg: 50.0°F), while the coldest was 1992 (avg: 44.1°F).
Average annual high/low · Last 30 years · °F
Total annual precipitation · Last 30 years · mm/year
| Year | Min Temp | Avg Temp | Max Temp | Rainfall (mm) | Avg Humidity | Avg Wind |
|---|---|---|---|---|---|---|
2025 | 36.0°F | 48.7°F | 61.5°F | 868 | 82% | 4.0 m/s |
2024 | 37.8°F | 49.8°F | 62.1°F | 1224 | 84% | 3.7 m/s |
2023 | 36.0°F | 48.9°F | 61.7°F | 1534 | 85% | 3.7 m/s |
2022 | 35.8°F | 48.9°F | 62.2°F | 1184 | 83% | 3.9 m/s |
2021 | 36.3°F | 49.3°F | 62.2°F | 1167 | 82% | 3.7 m/s |
2020 | 34.9°F | 48.7°F | 62.6°F | 1215 | 83% | 3.9 m/s |
2019 | 33.8°F | 47.1°F | 60.4°F | 1677 | 84% | 3.8 m/s |
2018 | 32.9°F | 47.7°F | 62.4°F | 1662 | 84% | 3.9 m/s |
2017 | 34.0°F | 48.0°F | 61.9°F | 1496 | 84% | 3.8 m/s |
2016 | 33.6°F | 48.0°F | 62.6°F | 1317 | 82% | 3.8 m/s |
Showing 1 to 10 of 45 years
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Based on 45 years of data (1981–2025), August is typically the hottest month in Portland, Maine, with average high temperatures around 75.2°F.
January is the coldest month in Portland, with average low temperatures around 8.5°F.
December receives the most rainfall with approximately 124 mm, while August is the driest with 86 mm.
The highest recorded temperature was 79.5°F in August 2010. This is part of the historical record spanning 1981–2025.
The lowest recorded temperature was -5.5°F in February 2023.
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.
Portland receives the most sunlight in July 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 and agriculture in Maine.
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.
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.
