Last and first frost dates in Allentown

When is the last frost in Allentown?

The last frost in Allentown usually comes around 15 April: 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 25 March, while corn waits until 22 April. The first autumn frost follows around 3 November, about 202 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 Allentown

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 11 days before the last spring frost and 15 °C 18 days after it.

Frost dates near Allentown

Of the nearest cities on our list, the last spring frost ends earliest in Dover (28 March) and latest in Harrisburg (10 April).

Seeds, seedlings and markets in Allentown

Within 15 km of Allentown OpenStreetMap lists 14 garden centres, 1 plant nursery, 6 markets and 7 farm shops (collected 29 October 2026). The nearest garden centre to the city centre is Lehigh Valley Home & Garden Center, 6 km away.

• Lehigh Valley Home & Garden Center — garden centre
  Crackersport Road 4178, 18104 Allentown · 6 km · lvhgc.com
• Downtown Allentown Market — market
  North 7th Street 27, 18101 Allentown · 1 km
• Dominican Produce — farm shop
  West Green Street 352, 18102 Allentown · 2 km
• Tall Timbers Nursery, Inc. — garden centre
  Huckleberry Road 4193, 18104 Allentown · 7 km
• Allentown Farmer's Market — market
  West Chew Street 1825, 18104 Allentown · Thu 09:00–19:00; Fri 08:00–19:00; Sat 08:00–18:00 · 2 km
• Saab Farmers Market — farm shop
  Union Boulevard 936, 18109 Allentown · 4 km

• Where to buy seeds and seedlings in Allentown
• Selling your own harvest in the United States

Places: © OpenStreetMap contributors, ODbL.

Weather in Allentown by month

Average weather in Allentown over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: May–September (21.6–30.2 °C). Months that average 30 °C or more by day: July (30.2 °C). Nights average below 0 °C in January (-4 °C), February (-2.9 °C) and December (-2 °C). About 1231 mm of rain falls in a year, on 132 days; August is the wettest month (127 mm) and November the driest (80 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).