New Castle has a warm temperate climate with warm summers and cold winters.
Temperatures peak in July and drop to their lowest in January, while rainfall is highest during summer months.
Humidity remains high throughout the year, especially during winter months, creating cold and damp conditions.
| Month | 🌤️ | Avg High | Avg Temp | Avg Low | Record High | Record Low | Humid % | Rain (mm) | Wind (m/s) | Solar (kWh/m²) |
|---|---|---|---|---|---|---|---|---|---|---|
| January | ❄️ | 38.7°F | 31.6°F | 24.4°F | 67.1°F | -11.6°F | 84% | 80 | 3.1 | 2.01 |
| February | 🌨️ | 41.9°F | 34.1°F | 26.3°F | 72.0°F | -1.7°F | 83% | 73 | 3.2 | 2.84 |
| March | ☔ | 50.7°F | 41.6°F | 32.5°F | 79.3°F | -2.9°F | 80% | 101 | 3.3 | 3.88 |
| April | ☔ | 61.8°F | 51.8°F | 41.9°F | 90.7°F | 20.1°F | 78% | 94 | 3.0 | 4.94 |
| May | ☔ | 71.3°F | 61.7°F | 52.1°F | 90.9°F | 34.5°F | 79% | 100 | 2.5 | 5.57 |
| June | ☔ | 80.7°F | 71.4°F | 62.1°F | 99.7°F | 44.1°F | 75% | 102 | 2.3 | 6.14 |
| July | ☔ | 86.5°F | 77.4°F | 68.3°F | 102.4°F | 50.9°F | 71% | 116 | 2.0 | 6.04 |
| August | ☔ | 85.2°F | 76.0°F | 66.8°F | 100.2°F | 46.6°F | 71% | 104 | 2.0 | 5.40 |
| September | ☔ | 78.9°F | 69.3°F | 59.7°F | 97.3°F | 40.1°F | 73% | 105 | 2.3 | 4.39 |
| October | ☔ | 67.0°F | 57.5°F | 47.9°F | 94.8°F | 27.9°F | 77% | 90 | 2.5 | 3.30 |
| November | ☔ | 54.9°F | 46.1°F | 37.4°F | 80.4°F | 20.8°F | 80% | 83 | 2.7 | 2.33 |
| December | ☔ | 43.9°F | 36.6°F | 29.3°F | 73.9°F | 0.3°F | 84% | 96 | 2.8 | 1.77 |
Showing average climate conditions across 45 years (1981–2025)
🧥 Expect frosty nights and below-freezing temperatures during this Cold Winter period.
🌤️ Early mornings and evenings are most comfortable during this Hot Summer season.
☔ 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 July, and gradually decline through autumn into winter.
These seasonal patterns make summer pleasant for travel, while winters can bring frost and occasional snowfall.
Monthly rainfall · 1981–2025 seasonal trends · mm/month
Rainfall is concentrated in the summer months. Humidity stays high (around 78%), peaking during winter 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, New Castle's temperature shows a slight warming trend over the past decade. Its hottest day reached 102.4°F in July 2012, and its coldest dropped to -11.6°F in January 1994. 2024 was the warmest year overall and 1996 the coolest.
The warmest year in New Castle's recorded history was 2024 (avg: 57.7°F), while the coldest was 1996 (avg: 51.6°F).
Average annual high/low · Last 30 years · °F
Total annual precipitation · Last 30 years · mm/year
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall (mm) | Avg Humidity | Avg Wind |
|---|---|---|---|---|---|---|---|---|
2025 | 64.9°F | 55.8°F | 46.8°F | 99.7°F | 10.4°F | 991 | 74% | 2.7 m/s |
2024 🔥 | 66.9°F | 57.7°F | 48.6°F | 97.7°F | 14.0°F | 1024 | 77% | 2.5 m/s |
2023 | 66.2°F | 57.0°F | 47.8°F | 97.3°F | 15.8°F | 1198 | 78% | 2.5 m/s |
2022 | 65.1°F | 55.9°F | 46.8°F | 98.4°F | 7.2°F | 1114 | 76% | 2.7 m/s |
2021 | 65.3°F | 56.7°F | 48.0°F | 97.0°F | 16.2°F | 1013 | 79% | 2.5 m/s |
2020 | 65.1°F | 56.5°F | 48.0°F | 96.8°F | 19.0°F | 1413 | 79% | 2.6 m/s |
2019 | 64.6°F | 55.9°F | 47.3°F | 94.8°F | 4.6°F | 1106 | 78% | 2.6 m/s |
2018 🌧️ | 63.1°F | 55.0°F | 46.9°F | 94.5°F | 0.5°F | 1577 | 82% | 2.7 m/s |
2017 | 64.8°F | 56.1°F | 47.3°F | 96.8°F | 10.8°F | 1096 | 77% | 2.7 m/s |
2016 | 64.8°F | 55.9°F | 46.9°F | 97.0°F | 7.7°F | 1040 | 77% | 2.6 m/s |
Showing 1 to 10 of 45 years
Based on 45 years of data (1981–2025), July is typically the hottest month in New Castle, Delaware, with average high temperatures around 86.5°F.
January is the coldest month in New Castle, with average low temperatures around 24.4°F.
July receives the most rainfall with approximately 116 mm, while February is the driest with 73 mm.
The highest recorded temperature was 102.4°F in July 2012. This is part of the historical record spanning 1981–2025.
The lowest recorded temperature was -11.6°F in January 1994.
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.
New Castle receives the most sunlight in June with an average solar radiation of 6.14 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning and agriculture in Delaware.
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.
