Potomac
United States · 7 July 2018
Average
22.6°C
low 18.6° · high 26.4°
Rainfall
0mm
dry day
Wind
3.3m/s
daily average
Humidity
51%
daily average
Cloud
49%
cover
Pressure
1025hPa
daily average
The temperature ranged from 18.6°C around 23:00 to 26.4°C around 17:00. No measurable rain was recorded during the day.
How unusual was this day?
Compared against the same 135 calendar days (±7 days) across the other 9 years on file.
High temperature
6th percentile
Low temperature
7th percentile
Rainfall
30th percentile
Wind
95th percentile
A percentile of 100 means this was the hottest/wettest/windiest of the comparable days on file; 50 is right in the middle. This window's average temperature was 26.6°C, versus 22.6°C on this specific day.
Sun & daylight
Sunrise
05:50
Sunset
20:37
Day length
14h 47m
Hour by hour
Temperature (line) and hourly rainfall (bars), local time — America/New_York.
Cumulative rainfall through the day.
| Local time | UTC | Temp °C | Feels °C | Rain mm | Wind m/s | Dir | Humidity % | Pressure hPa |
|---|---|---|---|---|---|---|---|---|
| 00:00 | 04:00 | 24.3 | 23.6 | 0 | 4 | NNE | 62 | 1021 |
| 01:00 | 05:00 | 23.6 | 22 | 0 | 4.9 | NNE | 62 | 1022 |
| 02:00 | 06:00 | 22.6 | 20.1 | 0 | 5.4 | NNE | 58 | 1022 |
| 03:00 | 07:00 | 21.7 | 18.7 | 0 | 5.3 | NNE | 54 | 1023 |
| 04:00 | 08:00 | 21 | 17.8 | 0 | 5 | NNE | 53 | 1023 |
| 05:00 | 09:00 | 19.5 | 15.9 | 0 | 4.8 | NNE | 51 | 1024 |
| 06:00 | 10:00 | 19 | 15.4 | 0 | 4.5 | NNE | 49 | 1026 |
| 07:00 | 11:00 | 18.9 | 15.8 | 0 | 3.9 | NE | 51 | 1027 |
| 08:00 | 12:00 | 19.1 | 16.3 | 0 | 3.8 | NNE | 54 | 1027 |
| 09:00 | 13:00 | 19.9 | 17.5 | 0 | 3.8 | NE | 56 | 1027 |
| 10:00 | 14:00 | 21.1 | 19.3 | 0 | 3.3 | NE | 55 | 1027 |
| 11:00 | 15:00 | 22.9 | 20.9 | 0 | 2.8 | NE | 44 | 1027 |
| 12:00 | 16:00 | 23.9 | 22.5 | 0 | 2.5 | ENE | 45 | 1027 |
| 13:00 | 17:00 | 24.3 | 23.2 | 0 | 2.2 | ENE | 44 | 1027 |
| 14:00 | 18:00 | 25 | 23.9 | 0 | 2.2 | ENE | 43 | 1027 |
| 15:00 | 19:00 | 25.9 | 24.9 | 0 | 2.4 | ENE | 43 | 1026 |
| 16:00 | 20:00 | 26.2 | 25.1 | 0 | 2.6 | ENE | 42 | 1026 |
| 17:00 | 21:00 | 26.4 | 25.3 | 0 | 2.6 | ENE | 41 | 1025 |
| 18:00 | 22:00 | 26 | 25.1 | 0 | 2.3 | ENE | 42 | 1025 |
| 19:00 | 23:00 | 25.4 | 24.2 | 0 | 2.5 | ENE | 43 | 1025 |
| 20:00 | 00:00 | 24 | 23.3 | 0 | 2.1 | ENE | 48 | 1025 |
| 21:00 | 01:00 | 21.9 | 21 | 0 | 2.1 | E | 53 | 1026 |
| 22:00 | 02:00 | 20.8 | 19.8 | 0 | 2.3 | E | 58 | 1026 |
| 23:00 | 03:00 | 18.6 | 18.1 | 0 | 2.5 | ESE | 75 | 1027 |
Nearby cities
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Data source & coverage — ERA5 reanalysis, 2016–2025 (10 years)details
- Source
- ERA5 reanalysis, accessed via the Copernicus Climate Change Service (C3S) Climate Data Store
- Data type
- Reanalysis — a physically consistent reconstruction combining a forecast model with historical observations, not a live station reading or a forecast
- Coverage
- 2016–2025 (10 years) for United States
- Location
- Potomac — 39.000°, -77.250°, ERA5 grid cell center, 4.1 km from requested point
- Time zone
- America/New_York
- What's shown here
- The hourly and daily record for 7 July 2018 specifically — not a monthly average. See the Potomac climate overview for typical conditions.
- Spatial resolution
- 0.25° (~25 km) distributed grid — ERA5's native model resolution is finer; this is the publicly distributed regridded product
- Version / refreshed
- Methodology v2026.07 · data last refreshed December 31, 2025
- Limitations
- A model reconstruction, not a station observation — hyper-local extremes (a single storm cell, an urban heat pocket) can differ from a nearby gauge. See the full methodology.
- Attribution
- Generated using Copernicus Climate Change Service information
Cite this data
PastClimate (2026-07-17). Historical climate data for Potomac, United States (39.00°N, 77.25°W), derived from ERA5 (Hersbach et al., 2023, Copernicus Climate Change Service). Retrieved from https://www.pastclimate.com/
PastClimate. (2026). Historical climate data for Potomac, United States [Data set]. Derived from ERA5 (Copernicus Climate Change Service). Retrieved July 17, 2026, from https://www.pastclimate.com/
"Historical Climate Data for Potomac, United States." PastClimate, derived from ERA5 (Copernicus Climate Change Service), July 17, 2026, www.pastclimate.com.
@misc{pastclimate,
author = {PastClimate},
title = {Historical climate data for Potomac, United States},
year = {2026},
note = {Derived from ERA5 (Hersbach et al., 2023), Copernicus Climate Change Service. Accessed 2026-07-17},
url = {https://www.pastclimate.com/}
}Notice something wrong with this data? Report a data issue.