Last Frost Date Îles-de-la-Madeleine — May 5
Last frost date on the Îles-de-la-Madeleine: May 5. First frost: November 5. Between them, 183 frost-free days — the longest season in Quebec, and it is the autumn that does it.
Last frost date Îles-de-la-Madeleine: May 5 on average. First fall frost: November 5. Frost-free period: 183 days, the longest anywhere in Quebec — Laval is next at 165, Montréal 151. The length comes almost entirely from the autumn, not from an early spring: still wait until late May or early June for tomatoes, peppers and basil. Source: Environment and Climate Change Canada 1991–2020 climate normals, composite station ILES DE LA MADELEINE (Climate ID 7053250), completeness code D — 18 years between 1991 and 2016, 3 missing. No citable hardiness zone exists for the islands; see below.
❄️ The Îles-de-la-Madeleine at a glance
183 frost-free days — the longest season in Quebec
This is the number that surprises people, and it is measured rather than estimated. The Îles-de-la-Madeleine publish 183 frost-free days. Laval, the longest on the Quebec mainland, has 165. Gatineau 159. Montréal 151. Across all 163 places we hold frost dates for, the islands rank 15th — and everything ahead of them sits on the British Columbia coast or in southern Ontario, hundreds of kilometres further south.
| Place | Prov. | Last frost | First frost | Frost-free days |
|---|---|---|---|---|
| Îles-de-la-Madeleine ⭐ | QC | May 5 | November 5 | 183 |
| Laval | QC | April 28 | October 10 | 165 |
| Halifax | NS | May 10 | October 18 | 161 |
| Gatineau | QC | April 30 | October 6 | 159 |
| Charlottetown | PE | May 10 | October 14 | 157 |
| Saint John | NB | May 8 | October 8 | 153 |
| Montreal | QC | May 9 | October 7 | 151 |
| Trois-Rivieres | QC | May 15 | October 5 | 143 |
| Sydney | NS | May 20 | October 10 | 143 |
| St. John's | NL | May 24 | October 13 | 142 |
A note on method, because it explains a one-day discrepancy: for every other place the day count is the span between our two published average dates. For the islands it is the average length of the frost-free period that ECCC publishes directly — 183 days, one fewer than the span from May 5 to November 5, because all three averages are computed separately. We publish ECCC's figure.
It is the autumn, not the spring
A long season sounds like an early spring. On the islands it is the opposite, and the distinction changes what you should actually do in the garden. The May 5 last frost is an ordinary date for the latitude. It is the November 5 first frost that is remarkable — roughly three weeks later than Montréal, a month later than Québec City.
The mechanism is the Gulf. Water warms slowly in spring and cools slowly in autumn, and an archipelago a few kilometres wide follows the water's curve rather than the land's. The clearest signature is in the temperature normals: the warmest month on the islands is August, not July.
| Station | July | August | October | Year |
|---|---|---|---|---|
| ILES DE LA MADELEINE | 17.7 °C | 18.4 °C | 9.0 °C | 5.6 °C |
| MONTREAL TRUDEAU | 21.7 °C | 20.6 °C | 8.9 °C | 7.0 °C |
Four degrees cooler in July, and yet frost arrives three weeks later. That is the whole story in one line: a long, cool season, not a long, warm one. And by October the two stations have almost converged — 9.0 against 8.9 °C — except that Montréal will already have frosted and the islands will not.
What it changes in the garden
The 183-day figure is easy to misread. Here is what it buys and what it does not.
It does not move spring forward. Soil on a wind-swept archipelago warms slowly, and May 5 is not an early date. Tomatoes, peppers, basil, squash and beans still wait for late May or early June, as they do everywhere in Quebec. A tender transplant set out mid-May gains nothing and risks everything.
It lengthens autumn enormously. That is where the gain is. Successions sown into early August have time to finish: lettuce, spinach, radishes, arugula, turnips, Swiss chard. Roots and greens hold into November, and the frost that eventually arrives sweetens carrots, parsnips and Brussels sprouts rather than ending them.
The real constraints are accumulated heat, then wind. Melons, eggplant and peppers struggle despite the 183 days, because they count degree-days rather than days — greenhouse, tunnel, or early varieties. And salt wind does more damage than a late frost: a shelterbelt of rugosa rose, sea buckthorn or white spruce is worth more to an island vegetable garden than any variety choice.
The station, and what it actually measures
These dates come from the ECCC composite station named ILES DE LA MADELEINE, Climate ID 7053250. Three things are worth stating plainly, because a figure without its provenance is not worth much.
First, the station is composite — four IDs, all on the islands. ECCC builds a normal from successive stations when no single one ran for the whole period. This one joins 7053250, 7053254, 705C2G9 and 7053KGR, all near 47°25′N, 61°47′W at 7.6 to 10.7 m elevation, by the Havre-aux-Maisons airport. No mainland station is folded in. For the frost elements specifically, two threads are used: 705C2G9 to 13 March 2013, then 7053KGR to 31 January 2016.
Second, this is not a full 30-year normal. All three frost values rest on 18 years between 1991 and 2016, with 3 missing — 69.2% of possible observations. ECCC rates them code D, which means "at least 15 years" (A means a near-complete series). ECCC itself writes on that page that a composite with 30 years and no missing years is a more reliable normal than one with 15 years and 2 missing. So the 183 days are a genuine multi-year measurement, and a weaker one than a full normal. The temperature normals above do cover the full 30 years and carry code A.
Third, the reading is taken at the airport, on Île du Havre aux Maisons, about ten metres above the sea. On an archipelago this narrow no garden is far from water, so the gap between the station and a vegetable plot at Fatima or Grande-Entrée stays small — far smaller than between a mainland airport and the downtown it is taken to represent.
Hardiness zone: we do not have one, and will not invent one
Every other city page on this site shows a hardiness zone. This one shows none, deliberately.
Natural Resources Canada is the only authority for a Canadian hardiness zone, and its municipality lookup has no entry for the Îles-de-la-Madeleine. Computing one ourselves would be original research a reader could mistake for an official figure, and inferring one from a mainland city would be plainly wrong — the Gulf's moderation is exactly what makes the islands different. An absent field is more honest than an invented one.
To get the zone for your own ground, check NRCan's map directly: planthardiness.gc.ca. It accepts coordinates and covers ground its municipality list does not.
Why a mainland station cannot stand in
The question comes up naturally: with no local data, could you borrow Gaspé's, Charlottetown's or Sydney's? The answer is no, for two reasons — and happily it is academic, because the islands have their own station.
| Station | Province | Distance |
|---|---|---|
| CHETICAMP | NS | 107 km |
| MONTICELLO | PE | 119 km |
| CHARLOTTETOWN A | PE | 163 km |
| SYDNEY A | NS | 192 km |
| CAUSAPSCAL — nearest in Quebec | QC | 420 km |
The first reason is distance: the nearest Quebec station, Causapscal, is 420 km away, inland in the Matapédia valley. The second is more decisive — it is not the same climate. Charlottetown, 163 km off, publishes 157 frost-free days; Sydney, 192 km off, publishes 143; the islands publish 183. An island gardener planning from Charlottetown's dates would lose the better part of a month of autumn. That is precisely the mistake this page exists to prevent.
Îles-de-la-Madeleine — Frequently Asked Questions
What is the last frost date on the Îles-de-la-Madeleine?
The average last spring frost on the Îles-de-la-Madeleine (the Magdalen Islands) is May 5, measured at the composite station ILES DE LA MADELEINE, Climate ID 7053250, in Environment and Climate Change Canada's 1991–2020 climate normals. The average first fall frost is November 5, and the published frost-free period is 183 days. One qualification matters: that average rests on 18 years of record between 1991 and 2016 with 3 missing years, not a full 30-year normal. ECCC rates it completeness code D, meaning at least 15 years. It is a real, multi-year measurement and a weaker one than a full normal, and this page says so wherever the figure appears.
Why is the frost-free season so long on the Îles-de-la-Madeleine?
Because the Gulf of St. Lawrence sets the calendar, not the continent. Water warms slowly in spring and cools slowly in autumn, and an archipelago a few kilometres wide with water on every side follows the water's curve rather than the land's. The temperature normals show it plainly: the warmest month on the islands is August, at 18.4 °C daily average, not July at 17.7 °C — a classic maritime lag. And it is the autumn, not the spring, that does the work: the last spring frost lands on an ordinary date for the latitude, but the first fall frost holds off until November 5.
Do the Îles-de-la-Madeleine really have Quebec's longest growing season?
Yes, among every place we hold data for. The islands' 183 frost-free days beat Laval (165), Gatineau (159) and Montréal (151), the longest on the Quebec mainland. Across all 163 places on this site the islands rank 15th, and everything above them is coastal British Columbia or southern Ontario. The cleanest comparison is same-period, same-kind-of-station: the islands publish 183 days in the 1991–2020 normals, and Montréal-Trudeau publishes 167 in the same normals. Measured identically, the islands still run about two weeks longer.
Can you plant earlier on the Îles-de-la-Madeleine?
No, and that is the most expensive way to misread 183 days. The long season is almost entirely at the back end. A May 5 last frost is not early, and the soil on a wind-exposed archipelago warms slowly. Tender crops — tomatoes, peppers, basil, squash, beans — still wait for late May or early June, as they do everywhere in Quebec. What the season buys is the other end: an extra month in autumn, so successions can be sown into August and greens and roots harvested into November.
What hardiness zone are the Îles-de-la-Madeleine in?
We do not know, and we would rather say so than invent a number. Natural Resources Canada is the only authority for a Canadian hardiness zone, and its municipality lookup has no entry for the Îles-de-la-Madeleine. Computing one ourselves would be original research a reader could mistake for an official figure. Check NRCan's map directly at planthardiness.gc.ca, which accepts coordinates and covers ground its municipality list does not. One thing is certain: a zone borrowed from a mainland city would be wrong, because the Gulf's moderation is exactly what makes the islands different.
Can I use frost dates from Gaspé, Charlottetown or Sydney instead?
No. The nearest ECCC station to the islands that publishes a frost normal is Chéticamp, Nova Scotia, 107 km away across open water, then Monticello PEI at 119 km, Charlottetown at 163 km and Sydney at 192 km. The nearest Quebec station is Causapscal at 420 km, inland in the Matapédia valley — a continental climate with nothing in common. None is a defensible proxy, and the numbers show why: Charlottetown publishes 157 frost-free days and Sydney 143, against the islands' 183. Happily the question is moot, because the islands have their own station, on the islands.
Which station do these dates come from?
The ECCC composite station named ILES DE LA MADELEINE. ECCC builds a normal from several successive stations when no single one ran for the whole period; this one draws on four — 7053250, 7053254, 705C2G9 and 7053KGR — all sitting near 47°25'N, 61°47'W at 7.6 to 10.7 m elevation, which is to say all on the islands, near the Havre-aux-Maisons airport. No mainland station is folded in. For the frost elements specifically, two threads are used: 705C2G9 to 13 March 2013, then 7053KGR to 31 January 2016.
What grows well on the Îles-de-la-Madeleine?
The constraint is heat, not frost. With 183 frost-free days but daily averages of 17.7 °C in July and 18.4 °C in August — about 4 °C below Montréal — the season is long and cool rather than long and warm. Cool-season crops do well: cabbage, kale, broccoli, cauliflower, carrots, beets, turnips, potatoes, peas, spinach, lettuce, onions, garlic. Heat-accumulating crops — melons, eggplant, peppers, late tomatoes — struggle despite the day count, because they count degree-days rather than days, and want a greenhouse, a tunnel or early varieties. Then there is salt wind, which is the real limiting factor: a shelterbelt does more for an island garden than any variety choice.
📍 Plan your season
Plan your 183 days
The gain is in the autumn: set the calculator to the islands and see how far your successions can run before November 5.