Planting zone for 84017 — Coalville, UT
ZIP code 84017 (Coalville, Summit County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is June 7 and the first fall frost September 12.
Where ZIP 84017 is
Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoomNot the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.
Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →
Frost forecast — next 7 nights
live from the National Weather ServiceLoading the forecast for Coalville, UT…
Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.
Frost dates in Coalville, UT
A hard freeze (28 °F) usually ends around May 21 and returns around September 25.
From the NOAA station Coalville, UT — 10 miles away, elevation 5,551 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.
When to plant vegetables in 84017
Counted from the median last spring frost (Jun 7) and first fall frost (Sep 12) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.
When spring arrived in 2026
In 2026, spring leaf-out near 84017 came on Mar 28 — 24 days earlier than the 1991–2020 average (Apr 21).
Apr 212026
Mar 28
The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).
Soil in Coalville, UT
The soil mapped at the center of ZIP 84017 is Dastrup — loam, well drained.
Map unit: Dastrup loam, 2 to 5 percent slopes.
Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 84017; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Coalville, UT
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Coalville 13 E, UT (4 mi away); precipitation: Chalk Creek #2, UT (9 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.
Questions about 84017
What planting zone is ZIP code 84017?
ZIP code 84017 (Coalville, UT) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).
When is the last frost in Coalville, UT?
The median last spring frost (32 °F) near 84017 is June 7; after June 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Coalville station.
When is the first frost in Coalville, UT?
The median first fall frost near 84017 is September 12, giving a median frost-free growing season of 95 days.
When should I plant tomatoes in 84017?
Start tomato seeds indoors around Apr 12 – Apr 26 and set transplants outside around Jun 14 – Jun 28, one to three weeks after the median last frost.
How much rain and snow does 84017 get?
About 29 inches of precipitation a year (NOAA 1991–2020 normals, Chalk Creek #2 station).
How hot do summers get in Coalville, UT?
The average high peaks at 78 °F in July, with about 4 days a year at 90 °F or more.
What kind of soil does 84017 have?
The USDA soil survey maps Dastrup at the center of ZIP 84017: loam, well drained, pH about 7.6 (slightly alkaline).
Did spring come early in Coalville, UT in 2026?
Spring leaf-out near 84017 came on Mar 28 in 2026, 24 days earlier than the 1991–2020 average (Apr 21), according to the USA National Phenology Network Spring Index.
What kind of onions grow in Coalville, UT?
Long-day onions: the longest day near 84017 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).