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Race Overview
The Founders Half Marathon is a 13.1-mile out-and-back race in Potomac, Maryland, organized by the DC Road Runners Club. The course runs along the C&O Canal Towpath from the Carderock Recreation Area, with two water stops at Lock 10 and Lock 6 passed twice each. It is race #2 of DCRRC's winter Snowball Series and was known as the Gar Williams Half Marathon before 2025, named for a past president of the club and of the Road Runners Club of America.
WikipediaFAQ
When is the 2026 Founders Half Marathon?
The 2026 Founders Half Marathon will be held on Sunday December 13, 2026.
Founders Half Marathon Weather History
Founders Half Marathon Weather Averages
Average Temp: 38°, Average Low: 30°, Average High: 45°
| Time | 9AM | 10AM | 11AM | 12PM | 1PM | 2PM | 3PM | 4PM |
|---|---|---|---|---|---|---|---|---|
| Temp | 38° | 39° | 40° | 42° | 42° | 42° | 42° | 41° |
| Feel | 33° | 35° | 35° | 36° | 36° | 37° | 36° | 36° |
| Rain | - | - | - | - | - | - | - | - |
| Wind | 8mph | 8mph | 9mph | 8mph | 8mph | 9mph | 11mph | 9mph |
| Dew | 29° | 29° | 28° | 27° | 27° | 25° | 25° | 24° |
| RunScore |  | | |  | | | | |
Founders Half Marathon 2025
Dec 14, 2025
Partly cloudy throughout the day with rain or snow clearing later.
Low: 18°, High: 38°, Moderate Rain
| Time | 9AM | 10AM | 11AM | 12PM | 1PM | 2PM | 3PM | 4PM |
|---|---|---|---|---|---|---|---|---|
| Temp | 29° | 29° | 29° | 29° | 28° | 26° | 26° | 23° |
| Feel | 17° | 17° | 15° | 16° | 15° | 12° | 11° | 8° |
| Rain | - | - | - | - | - | - | - | - |
| Wind | 18mph | 18mph | 23mph | 19mph | 20mph | 22mph | 24mph | 23mph |
| Dew | 20° | 18° | 16° | 14° | 12° | 8° | 7° | 4° |
| RunScore |  |  |  | | | | | |
Founders Half Marathon 2024
Dec 1, 2024
Partly cloudy throughout the day.
Low: 24°, High: 43°
| Time | 9AM | 10AM | 11AM | 12PM | 1PM | 2PM | 3PM | 4PM |
|---|---|---|---|---|---|---|---|---|
| Temp |  31° | 35° | 38° | 41° | 41° | 43° | 42° | 41° |
| Feel | 31° | 35° | 34° | 37° | 37° | 40° | 36° | 35° |
| Rain | - | - | - | - | - | - | - | - |
| Wind | 2mph | 1mph | 5mph | 6mph | 6mph | 5mph | 9mph | 9mph |
| Dew | 22° | 22° | 19° | 20° | 19° | 20° | 20° | 21° |
| RunScore | | |  | | | | | |
Founders Half Marathon 2023
Dec 3, 2023
Cloudy skies throughout the day with rain clearing later.
Low: 49°, High: 55°, Heavy Rain
| Time | 9AM | 10AM | 11AM | 12PM | 1PM | 2PM | 3PM | 4PM |
|---|---|---|---|---|---|---|---|---|
| Temp | 52° | 53° | 53° | 54° | 54° | 54° | 55° | 55° |
| Feel | 52° | 53° | 53° | 54° | 54° | 54° | 55° | 55° |
| Rain | light | light | - | - | - | - | - | - |
| Wind | 2mph | 2mph | 1mph | 1mph | 0mph | 1mph | 3mph | 2mph |
| Dew | 51° | 51° | 52° | 53° | 52° | 53° | 53° | 53° |
| RunScore | | | | | | |  | |
Founders Half Marathon 2022
Dec 4, 2022
Partly cloudy throughout the day.
Low: 30°, High: 46°
| Time | 9AM | 10AM | 11AM | 12PM | 1PM | 2PM | 3PM | 4PM |
|---|---|---|---|---|---|---|---|---|
| Temp | 38° | 40° | 42° | 43° | 43° | 46° | 46° |  46° |
| Feel | 32° | 34° | 38° | 39° | 39° | 42° | 42° | 46° |
| Rain | - | - | - | - | - | - | - | - |
| Wind | 9mph | 9mph | 7mph | 7mph | 7mph | 6mph | 7mph | 2mph |
| Dew | 25° | 25° | 25° | 23° | 23° | 20° | 20° | 19° |
| RunScore | | | | | | | | |