Bottineau County Frost Dates.
Probability table.
The median last spring frost in Bottineau County is May 5. The median first fall frost is October 3, giving a typical growing season of 151 days.
Data from WESTHOPE, ND US, 11.7 miles away with 30-year NOAA record (1991-2020).
The frost year, at a glance.
Pick your row by your appetite for risk.
Five risk tiers across three temperature thresholds. Most farmers plan against the conservative side for high-value transplants and the median for direct-seed crops. The aggressive rows are useful when paired with row cover or other season-extension tools.
Last Spring Frost
The range of last-frost dates seen across 1991–2020 at the killing-freeze (28°F) threshold and at the lighter 32°F and harder 24°F thresholds. For frost-sensitive transplants in Bottineau County, the "very conservative" row is the date frost has occurred at in only 1 of 10 historical years — i.e., the safe-side bound.
Reading: pick a row by your appetite for risk. Very conservative — the unluckiest 10% of years had frost past this date. Very aggressive — only the luckiest 10% of years were frost-free this early. Plant frost-sensitive transplants on the conservative side.
First Fall Frost
The range of first-frost dates in fall. For frost-sensitive harvests (winter squash, fall tomatoes, pumpkins), the "very conservative" row is the harvest deadline — frost has arrived this early in only 1 of 10 historical years.
Reading: pick a row by your appetite for risk. Very conservative — frost arrived this early in only the unluckiest 10% of years. Very aggressive — frost held off this late in only the luckiest 10% of years. Schedule frost-sensitive harvests on the conservative side.
Growing Season
Days between the last spring frost (28°F) and first fall frost (28°F). Plan for the shorter end if you're growing long-season crops without season-extension tools.
What this means for your crops
Crop-specific planting and harvest guidance derived from the frost probability data above. Each line uses the actual percentile dates from the nearest NOAA station — not a generic regional rule.
- TomatoesFull North Dakota calendar →Set transplants out after May 17 — that's the conservative bound where only 1 of 10 historical years had a 28°F frost past this date. For unprotected fields, waiting another 7 days for the soil to hold above 60°F gives a stronger start.
- PeppersFull North Dakota calendar →Peppers are more cold-sensitive than tomatoes. Hold transplants until May 24 — about a week past the conservative last-frost bound — and aim for 65°F+ soil temperature.
- Sweet cornFull North Dakota calendar →Direct seed sweet corn after May 14, when soil temperature reliably holds above 55°F. Sweet corn tolerates a light spring frost but won't germinate in cold ground.
- PumpkinsFull North Dakota calendar →For Halloween harvest, plant by June 3. That gives 110 days to reach the conservative first-fall-frost date (September 21) — frost has arrived this early in only 1 of 10 historical years, so most pumpkins will finish in time.
- PotatoesFull North Dakota calendar →Potatoes can go in around April 30 — about 2 weeks before the median 32°F last-frost date. The shoots tolerate a light frost; what you need is soil temperature above 45°F.
- Winter wheatFull North Dakota calendar →For optimal fall establishment, plant winter wheat around August 22 — six weeks before the median first 28°F freeze (October 3). That window gets the crop tillered before dormancy without pushing it too tall, where Hessian fly is a concern.
- Clover (cool-season)Full North Dakota calendar →Frost-seed clover in late winter when freeze-thaw cycles are still working the soil — typically 4–6 weeks before May 22. Clover germinates as soils warm and is well-rooted before grass competition kicks in.
- Winter rye (cover)Full North Dakota calendar →Winter rye is the most frost-tolerant cereal — plant by September 5, four weeks before the median first 28°F freeze. It can germinate in cool soil and will keep growing whenever temperatures are above freezing through fall.
These dates assume a healthy, well-drained field and standard varieties. Adjust for raised beds, row cover, or short-season varieties as appropriate.
Why your farm may differ from these dates.
The dates on this page come from the nearest qualifying NOAA station with a 30-year record. Real frost on a real field is shaped by terrain, water, and the built environment. Read the station data as a regional anchor, then adjust for what you know about your own ground.
- ElevationHigher ground frosts earlier in fall and later in spring. As a rule of thumb, expect roughly a 3–5°F difference in overnight low for every 1,000 feet of elevation change versus the nearest valley station.
- Cold air drainageOn clear, calm nights cold air sinks into low spots. Valley bottoms, hollows, and the bottom of orchard rows can frost 2–6 weeks differently than nearby slopes — even within a 100-yard radius. South-facing slopes warm faster in spring than north-facing slopes.
- Urban and suburban heatPavement, buildings, and irrigation push frost dates later than rural stations report. If your operation sits inside a metro area, the local last-frost date is often 1–3 weeks earlier than what a rural NOAA station shows.
- Water proximityLarge lakes, rivers, and especially the coast moderate temperature swings. Sites within a mile of a sizable water body typically see a later last-spring frost and an earlier first-fall frost than inland sites at the same latitude.
For precision frost monitoring, install a personal weather station on the field that matters most. The closer the sensor is to the soil surface where you actually plant, the more useful the data.
How this compares to USDA Zone 4a.
USDA Zone 4a measures average annual extreme minimum winter temperature for plant winter hardiness. The frost probability data on this page measures the actual range of last-spring and first-fall frost dates from the nearest NOAA weather station — far more useful for planning annual crop planting and harvest.
Plan for variability — not just the median.
The probability table above tells you the range. The median gives you 50/50 odds. The conservative end gives you 9-out-of-10 odds. Within Bottineau County, the difference between an early year and a late year for last spring frost can be about 27 days. Operations with row cover, low tunnels, or high tunnels can effectively shift the conservative end earlier; operations without protection should plan against the conservative bound.
The NOAA station behind these dates.
- UPHAM 3 N, ND US13.3 mi30-yr record
- BOTTINEAU, ND US17.3 mi30-yr record
- LAKE METIGOSHE SP, ND US26 mi30-yr record
Frost dates in nearby North Dakota counties.
- Bowman CountySpring May 5 · Fall Oct 3
- Kidder CountySpring May 5 · Fall Oct 5
- McIntosh CountySpring May 5 · Fall Oct 4
- Barnes CountySpring May 4 · Fall Oct 5
- Benson CountySpring May 4 · Fall Oct 8
- Foster CountySpring May 4 · Fall Oct 5
- Golden Valley CountySpring May 6 · Fall Oct 4
- Grand Forks CountySpring May 4 · Fall Oct 5