Last Frost Date Fredericton — May 17 (Zone 5b)
Last frost date Fredericton: May 17 for the urban core (Zone 5b). The Saint John River moderates the immediate riverbank (downtown, Devon, Oromocto); inland Nashwaaksis, New Maryland, and Hanwell run 3–10 days later. Historical range, frost protection, and a 9-community breakdown.
Last frost date Fredericton 2026: May 17 for the urban core (downtown, Devon, North Side) — hardiness Zone 5b. Riverbank pockets (Officers Square, King Street): May 13–17. Oromocto: May 15–18. Nashwaaksis, Marysville: May 17–20. New Maryland: May 20–25. Hanwell, Beaver Dam Brook (inland, elevation): May 20–28. Wait until May 28–June 5 to transplant tomatoes, peppers, basil. Historical range: early May (earliest) to early June (latest). Source: Environment and Climate Change Canada climate normals (1991–2020).
❄️ Fredericton Frost Dates at a Glance
Last Frost Date Fredericton — Historical Average
The last frost date for Fredericton — May 17 for the urban core — is the 50th-percentile historical average drawn from Environment and Climate Change Canada climate normals for the 1991–2020 reference period. In plain terms: roughly half of recent years have seen Fredericton's last spring frost before May 17, and half after. It is a planning anchor with meaningful year-to-year variation because Fredericton sits inland from the Bay of Fundy — about 100 km up the Saint John River — and loses some of the maritime moderation that Saint John NB enjoys.
The full historical range is wider than many gardeners realize. The earliest last spring frost recorded in modern records for Fredericton's urban core is around May 1; the latest is around June 8. That's a 38-day window. The Saint John River runs through downtown and provides 2–4 days of moderation along the immediate riverbank, but inland areas behave more like interior Maine — with all the late-spring frost risk that comes with it. A warm late winter can pull the last frost forward by two weeks; a cold spring with persistent low pressure off the Gulf of St. Lawrence can push it into early June.
The 1991–2020 normals replaced the older 1981–2010 set in 2021. Compared to the older period, Fredericton's average last frost has shifted about 3–5 days earlier due to gradual warming. ECCC updates its 30-year normals every decade, so the May 17 figure will hold as the official average until the next update around 2031.
Last Frost by Fredericton Neighbourhood and Surrounding Community
Frost dates across Greater Fredericton vary by 7–14 days based on proximity to the Saint John River and elevation. The river itself moderates the immediate riverbank strongly — downtown and Devon get a noticeable head start over inland Nashwaaksis. New Maryland and Hanwell sit on higher ground and routinely see frost a week later than downtown. Oromocto, downriver and on the floodplain, shares the urban-core timing thanks to river moderation.
| Community / Area | Last Frost | Zone |
|---|---|---|
| Downtown (Officers Square, King Street, riverbank) | May 13–17 | 5b/6a |
| Devon / North Side waterfront | May 14–18 | 5b |
| Oromocto (downriver, floodplain) | May 15–18 | 5b |
| Fredericton urban core (general) | May 17 | 5b |
| Nashwaaksis, Marysville, Barker's Point | May 17–20 | 5b |
| Lincoln, Fredericton Junction | May 17–20 | 5b |
| New Maryland (south, elevation) | May 20–25 | 5a/5b |
| Hanwell, Beaver Dam Brook (inland) | May 20–28 | 5a |
| McAdam, Harvey (inland west) | May 22–30 | 4b/5a |
Dates derived from ECCC climate normals (1991–2020) and station-by-station observations across Greater Fredericton and the Saint John River valley.
How to Protect Plants from a Late Fredericton Frost
A late frost after May 17 happens roughly 1 year in 5 in Fredericton's urban core, more often in New Maryland and Hanwell. Late Fredericton frosts are usually -1 to -3°C and often arrive on clear calm nights after warm days — the classic radiation-frost pattern that catches gardeners off guard. Four protection methods:
- Floating row cover (Reemay, Agribon): draped over transplants in the evening, removed in the morning. Protects to about -3°C. Available at Halifax Seed, Country Stores, Home Hardware, and Canadian Tire across NB.
- Cloches and individual covers: inverted 4 L plastic milk jugs, commercial cloches, or cut 2 L pop bottles work for 5–10 individual tomato or pepper transplants.
- Heavy mulch: 5–10 cm of straw, salt-marsh hay, or shredded leaves around transplants insulates roots and buffers overnight temperature swings by 2–3°C.
- Warm microclimates: plant tender crops against a south-facing fence, brick wall, or in a riverbank garden where the Saint John River buys 3–4 days of moderation. Avoid frost pockets at the base of New Maryland's hills.
The golden rule for Fredericton: never transplant tomatoes, peppers, basil, beans, or squash if nights below 5°C are forecast within 7 days. Watch clear-sky forecasts in late May closely — those are the radiation-frost conditions that produce -3°C overnight in New Maryland and Hanwell while downtown stays at +2°C.
What to Plant Before vs. After Fredericton's Last Frost
❄️ Before May 17 (frost-tolerant)
- Direct sow mid-April: peas, spinach, radishes, lettuce, arugula, kale
- Direct sow late April: carrots, beets, Swiss chard, parsnips, turnips
- Transplant late April/early May: broccoli, cabbage, cauliflower, kohlrabi
- Transplant early May: onions, leeks, hardy herbs
- Plant fall (mid-October): hardneck garlic — overwinters reliably
⚠️ After May 28 (frost-sensitive)
- Tomatoes: transplant May 28–June 5 (65–75 day varieties)
- Peppers: transplant June 5–10 (soil at 15°C)
- Basil: June 5 minimum — cold damages it permanently
- Beans, cucumbers, squash: direct sow late May/early June
- Melons, eggplant: marginal in Zone 5b — short-season varieties only
How Fredericton's Frost Date Compares to Other Canadian Cities
Fredericton's May 17 last frost is later than its Atlantic neighbours (Halifax May 10, Saint John NB May 8, Charlottetown May 14, Moncton May 15) thanks to its inland position 100 km up the Saint John River. Within Atlantic Canada, only St. John's NL (May 28) and Cape Breton (May 15–20) frost later. Compared to central Canada, Fredericton's May 17 is similar to Quebec City (May 17) and a week later than Montreal/Ottawa (May 9).
| City | Last Frost | Zone | vs Fredericton |
|---|---|---|---|
| Saint John NB | May 8 | 6a | 9 days earlier (Bay of Fundy) |
| Halifax | May 10 | 6a | 7 days earlier |
| Charlottetown PEI | May 14 | 6a | 3 days earlier |
| Moncton | May 15 | 5b | 2 days earlier |
| Fredericton | May 17 | 5b | — |
| Quebec City | May 17 | 4b | same date, colder zone |
| St. John's NL | May 28 | 6a | 11 days later |
Common Questions about Fredericton's Last Frost
When can I safely transplant tomatoes in Fredericton?
May 28–June 5 in Fredericton's urban core, slightly earlier along the riverbank, and June 5–10 in New Maryland and Hanwell. Tomatoes need both frost-free conditions and warm soil (above 12°C at 5 cm depth). Fredericton's 131-day growing season is shorter than Halifax's, so stick to 65–75 day cultivars (Bush Beefsteak, Manitoba, Scotia) for reliable maturity before the September 26 first fall frost. Harden off transplants 7–10 days before setting them out.
Why does Fredericton freeze later than Saint John?
Saint John NB sits directly on the Bay of Fundy — one of the coldest large bodies of water in North America — which keeps spring air temperatures down but also prevents the warm-day/cold-night swings that produce radiation frosts. Fredericton is about 100 km up the Saint John River, well inland from the Fundy moderation. The river itself helps the immediate downtown riverbank, but Fredericton's inland-continental position adds 9 days to the last frost average (May 17 vs Saint John's May 8) and gives Fredericton a notably more variable spring.
What hardiness zone is Fredericton?
Fredericton's urban core is Zone 5b under the Canadian Plant Hardiness Zone system — comparable to Montreal, Ottawa, and Moncton. The immediate riverbank (downtown waterfront) approaches Zone 6a in protected spots. New Maryland, Hanwell, and other inland-elevated communities drop to Zone 5a. A Zone 5 plant will survive reliably in any Fredericton garden; Zone 6 plants are reliable in sheltered downtown gardens but risky farther from the river.
When is the first fall frost in Fredericton?
Around September 26 for Fredericton's urban core — about two days earlier than Moncton and two weeks earlier than Toronto. Inland communities (Hanwell, McAdam) can frost in mid-September. The fall frost arrives faster and harder than the spring frost: a clear cold late-September night can drop temperatures to -2°C and end the tomato season overnight. Many Fredericton gardeners buy themselves 7–10 extra harvest days by covering tomatoes and peppers with row cover on forecast frost nights.
📍 New Brunswick Garden Resources
Plan Your Fredericton Garden Season
Combine Fredericton's May 17 frost date with your exact postal code in the frost calculator and the seed-starting calculator to build a precise planting schedule for the Saint John River valley's 131-day Zone 5b season.