Frost dates for Portsmouth, Virginia
Virginia · first & last freeze, from NOAA 1991–2020 climate normals
In a typical year, the last spring freeze around Portsmouth comes near March 16 and the first fall freeze near November 26. One year in ten, a freeze still arrives after April 1 in spring — and one year in ten, the first fall freeze has already landed by November 8. NCEI's own growing-season statistic (days between freezes, percentiled per year) puts the median at 255 days.
Freeze-date probabilities, three thresholds
| Threshold | Last spring — 9 in 10 years past by | Last spring — typical (median) | Last spring — 1 in 10 years later than | First fall — 1 in 10 years by | First fall — typical (median) | First fall — 9 in 10 years by |
|---|---|---|---|---|---|---|
| 36°F — near-freezing (frost can occur) | March 12 | March 29 | April 10 | November 1 | November 14 | November 29 |
| 32°F — freezing | February 26 | March 16 | April 1 | November 8 | November 26 | December 17 |
| 28°F — hard freeze | February 9 | March 2 | March 19 | November 21 | December 12 | January 5 |
Measured at Norfolk Nas, VA (USW00013750), 7.5 mi from the city's census reference point, elev. 17 ft. NOAA/NCEI 1991–2020 normals. Read each date column as odds over the 30-year record — e.g. "9 in 10 years past by" means only one spring in ten saw a later freeze than that date.
Frost-free windows (computed)
| Window (32°F ends) | Opens | Closes | Length |
|---|---|---|---|
| Cautious (1-in-10 freeze risk at each end) | April 1 | November 8 | 221 days |
| Typical (median freeze dates) | March 16 | November 26 | 255 days |
| Gambler's (9-in-10 freeze risk at each end) | February 26 | December 17 | 294 days |
Pure arithmetic on the freeze-date percentiles above — the "cautious" window opens on the date only 1 year in 10 still sees a later spring freeze, and closes on the date by which only 1 year in 10 has already frozen.
About this city's numbers
- Census entity: Portsmouth city, Virginia — official 2024 population estimate 96,482.
- Weather station: Norfolk Nas, VA (USW00013750), 7.5 mi from the city's census-gazetteer reference point at elevation 17 ft. Frost dates are that station's history — neighborhoods vary.
- Data pulled 2026-09-05; normals period 1991-2020 (replaced by NOAA roughly once a decade).
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