Last and first frost dates in Letterkenny

When is the last frost in Letterkenny?

The last frost in Letterkenny usually comes around 30 March: that is the median of 2016–2025, so in about half of those years the last night at or below 0 °C came later. Hardy crops start before it and frost-tender ones only after it: in the table below arugula can go into open ground from 9 March, while corn waits until 12 May. The first autumn frost follows around 28 November, about 243 days later: harvest or cover frost-tender crops before then.

When to sow and plant

Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

When the soil warms up in Letterkenny

The day the top 7 cm of soil first averages each temperature over a week, median of 2016–2025 (ERA5 via Open-Meteo). The soil reaches 10 °C 31 days after the last spring frost and 15 °C 69 days after it.

Frost dates near Letterkenny

Of the nearest cities on our list, the last spring frost ends earliest in Dundalk (20 March) and latest in Belfast (18 April).

Seeds, seedlings and markets in Letterkenny

Within 15 km of Letterkenny OpenStreetMap lists 3 garden centres and 1 market (collected 28 October 2026). The nearest garden centre to the city centre is Gary's Petworld and Garden Centre, 2 km away.

• Gary's Petworld and Garden Centre — garden centre
  Mon–Fri 09:00–18:00 · 2 km

• Where to buy seeds and seedlings in Letterkenny
• Selling your own harvest in Ireland

Places: © OpenStreetMap contributors, ODbL.

Weather in Letterkenny by month

Average weather in Letterkenny over 2016–2025: the warmest month is August. No month averages 20 °C by day; the warmest, August, reaches 17.7 °C. No month averages below 0 °C at night; the coldest nights, in January, average 2.7 °C. About 1237 mm of rain falls in a year, on 209 days; August is the wettest month (126 mm) and April the driest (77 mm).

Average of the daily highs and lows, rain per month and days with at least 1 mm (ERA5 via Open-Meteo, the same grid cell as the frost dates).

Planted in autumn

From a month before the first autumn frost, so the roots grow before winter, to the late-planting limit on each crop’s page (about two weeks before the ground freezes, by ten years of weather).