Frost Dates for 46409 — Gary, Indiana

Half of springs at Indiana Dunes Nl, IN see their last 32°F night by April 22; only one in ten is past it by April 7, and one in ten still has one after May 8. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 8 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 35% of the 125 Indiana stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 27 in half of years, as early as October 15 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 11 days later, around November 7; in spring the one-in-ten date for 28°F is April 23, 15 days before the 32°F one. The freeze-free season lasts 188 days in a typical year, longer than at 69% of the 125 Indiana stations; it reaches 209 days one year in ten and falls short of 167 one year in ten. On average 117 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 12 days longer, to about May 4, and return around October 16. Severe cold of 16°F or below comes every winter, usually between December 8 and March 6.

July is the warmest month at Indiana Dunes Nl, IN, averaging 82°F by day and 64°F at night; January is the coldest at 32°F and 18°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 24% of years.

Warmth for growing adds up to 3,043 growing degree days a year (base 50°F), fewer than at 86% of the 125 Indiana stations. 33% of them (991) have built up by the end of June, and July adds the most, 711. Precipitation totals 39.4 inches a year, most in May (4.3") and least in February (2.0"); May to September bring 52% of it.

The nearest other station, Valparaiso Wtr Wks, IN, 15 miles east of Gary, has the same 50% last-frost date, a first frost 2 days earlier (October 25), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Gary usually arrives around December 7, and the last of the season around March 17. Those are the middle dates across the winters of 1991–2020 at Crown Pt 1N, IN, 7.4 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 36 days after the last snow.

ZIP 46409 is 14 miles from Indiana Dunes Nl, IN, which stands at 680 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 9 other ZIP codes share the station; its figures are presented in full for 46368 (Portage). The 2023 USDA Plant Hardiness Zone Map lists ZIP 46409 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.