Treynor, Iowa Weather
Prairie lightning bugs rise. Day 77 of spring. Read this microseason across nine climate regions →
Treynor weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Showers55%0.28″77°65°—
- FridayJun 5Thunderstorm73%—85°66°+8°
- SaturdayJun 6Drizzle73%—85°65°0°
- SundayJun 7Light Showers61%0.02″79°66°-6°
- MondayJun 8Drizzle46%—85°65°+6°
- TuesdayJun 9Thunderstorm18%—91°68°+6°
- WednesdayJun 10Thunderstorm10%—93°75°+2°
AQI 29 (Good), driven by Ozone. AQI down 21 over the last 6 hours — air quality is improving sharply.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 8 AM.
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:55 AM
- Moonset
- 2:21 PM
- In sign
- ♑︎ Capricorn
Prairie lightning bugs rise
Treynor at a glance
- Today vs. normal: 5°F below the seasonal normal for this latitude
- Last frost: April 23 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
SPC Convective Outlook
Storm Prediction Center — Treynor
SPC has placed Treynor in the Slight Risk category for severe thunderstorms tomorrow.
- TODAYMRGLMarginal Risk
- TOMORROWSLGTSlight Risk
- DAY 3SLGTSlight Risk
Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Treynor's warmest month is July (~74°F mean) and its coldest is January (~21°F). Rainfall peaks in May (5.4 inches) and bottoms out in January (0.8 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 21° | 0.8″ | 2 |
| February | 25° | 1.1″ | 3 |
| March | 38° | 2.0″ | 4 |
| April | 49° | 3.9″ | 7 |
| May | 61° | 5.4″ | 9 |
| June | 71° | 5.3″ | 7 |
| July | 74° | 3.6″ | 6 |
| August | 72° | 4.9″ | 5 |
| September | 65° | 3.6″ | 5 |
| October | 52° | 3.0″ | 5 |
| November | 38° | 1.6″ | 3 |
| December | 26° | 1.3″ | 3 |
Regional context
Treynor's baseline climate, derived from NOAA NCEI 1991-2020 normals at the nearest reporting station, swings from a January mean of 21°F to a July mean of 74°F — a 54°F seasonal arc typical of the mid-latitude bands. Annual precipitation runs about 36.4 inches spread across roughly 59 days with measurable rain or snow each year.
Precipitation runs summer-dominant here: May averages 5.4 inches across 9.0 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while January drops to just 0.8 inches across 2.3 rainy days under drier cool-season air. That wet-warm-summer pattern groups Treynor with places like Mineola, IA, McClelland, IA and Silver City, IA — a regional cohort where summer thunderstorm season carries more than half the annual moisture.
The frost-sensitive growing window opens around mid-April, when overnight lows reliably clear freezing for cool-season crops like kale, peas, spinach, and parsnips. Warm-season transplants — tomatoes, peppers, and basil — typically wait two weeks past that date to avoid late spring cold snaps. The window closes around mid-November, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. These dates represent 30-year central tendencies; actual year-to-year variation can shift either bookend by 7-14 days, and local microclimate features within Treynor — cold-air drainage on calm clear nights, slope aspect, distance from any nearby lake or river — can push the practical frost window earlier or later than the regional average.
Similar climates: Mineola, IA, McClelland, IA, Silver City, IA, Carson, IA, Macedonia, IA.
Frequently asked
- When does it freeze in Treynor?
- Treynor's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Treynor?
- May is the wettest month with about 5.4 inches of rain on average; the city receives roughly 36 inches annually.
- What is the warmest month in Treynor?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in Treynor?
- January is typically coldest, averaging about 21°F.
- When can I start a vegetable garden in Treynor?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Treynor get?
- Treynor averages about 59 rainy days per year.
- What hardiness zone is Treynor?
- Treynor's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Treynor, Iowa sits in a warm-summer humid continental climate zone. January means hover near 21°F while July averages 74°F — a 54°F seasonal swing.
Across the year, Treynor receives about 36 inches of precipitation spread over roughly 59 rainy days.
The rhythm of the year is set by latitude (41.2°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.