Greybull, Wyoming Weather
Pikas hayfeeding in granite peaks. Day 78 of spring. Read this microseason across nine climate regions →
Greybull weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——83°55°—
- FridayJun 5Partly Cloudy——90°54°+7°
- SaturdayJun 6Overcast——97°60°+7°
- SundayJun 7Overcast42%—85°63°-12°
- MondayJun 8Overcast22%—80°59°-5°
- TuesdayJun 9Overcast——85°65°+5°
- WednesdayJun 10Light Drizzle26%0.03″83°59°-2°
AQI 49 (Good), driven by Ozone. AQI up 6 over the last 6 hours (gradual rise). Ozone at AQI 36 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 9 by mid-afternoon.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 36 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 9 by mid-afternoon.
- Present
- AQI 36
- UV peak
- 0.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 9
PM × Wind × Precip
PM2.5/PM10 ratio 0.53 with 6 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.53
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- transport
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).
The higher the clouds, the finer the weather.
- Moonrise
- 6:27 AM
- Moonset
- 4:11 PM
- In sign
- ♒︎ Aquarius
Pikas hayfeeding in granite peaks
Greybull at a glance
- Today vs. normal: 3°F below the seasonal normal for this latitude
- Last frost: May 13 (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
Warm-season window is open
As of June 5, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
SPC Convective Outlook
Storm Prediction Center — Greybull
SPC has placed Greybull in the General Thunderstorms category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe risk
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
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 | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Greybull's warmest month is July (~73°F mean) and its coldest is January (~16°F). Rainfall peaks in May (1.4 inches) and bottoms out in March (0.2 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 16° | 0.3″ | 1 |
| February | 23° | 0.4″ | 1 |
| March | 37° | 0.2″ | 1 |
| April | 46° | 0.6″ | 2 |
| May | 56° | 1.4″ | 4 |
| June | 66° | 1.2″ | 3 |
| July | 73° | 0.5″ | 2 |
| August | 70° | 0.3″ | 1 |
| September | 60° | 1.0″ | 2 |
| October | 46° | 0.8″ | 2 |
| November | 31° | 0.4″ | 2 |
| December | 19° | 0.2″ | 1 |
Regional context
Greybull's climate, per the NOAA NCEI 1991-2020 normals from the nearest reporting station, runs cold-winter and warm-summer. January means hover near 16°F while July climbs to 73°F — a 57°F seasonal swing typical of northern-tier latitudes. Annual precipitation totals about 7.2 inches spread across roughly 22 days with measurable rain or snow.
Precipitation runs summer-dominant here: May averages 1.4 inches across 3.7 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while March drops to just 0.2 inches across 1.0 rainy days under drier cool-season air. The warm-season-wet rhythm lines Greybull up with places like Basin, WY, Shell, WY and Manderson, WY, where the May-September stretch delivers the bulk of the year's precipitation.
The frost-sensitive growing window opens around late-May, when overnight lows reliably clear freezing for cool-season crops like kale, peas, spinach, and parsnips. Heat-loving transplants like tomatoes, peppers, and squash generally hold off for another 10-14 days to clear the last spring frost risk window. The window closes around early-October, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. These are 30-year central tendencies; year-to-year frost dates can move by up to two weeks. Local features matter: a south-facing slope inside Greybull typically runs 3-5 days ahead of the regional last-frost date, while a low-lying lot along a creek or drainage can lag the same date by a week or more on calm clear nights.
Similar climates: Basin, WY, Shell, WY, Manderson, WY, Burlington, WY, Hyattville, WY.
Frequently asked
- When does it freeze in Greybull?
- Greybull's last spring frost typically falls around mid-May, and the first fall frost arrives around mid-October.
- What is the rainy season in Greybull?
- May is the wettest month with about 1.4 inches of rain on average; the city receives roughly 7 inches annually.
- What is the warmest month in Greybull?
- July is typically warmest, averaging about 73°F.
- What is the coldest month in Greybull?
- January is typically coldest, averaging about 16°F.
- When can I start a vegetable garden in Greybull?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-May); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Greybull get?
- Greybull averages about 22 rainy days per year.
- What hardiness zone is Greybull?
- Greybull'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
Greybull, Wyoming sits in a cold semi-arid climate zone. January means hover near 16°F while July averages 73°F — a 57°F seasonal swing.
Across the year, Greybull receives about 7 inches of precipitation spread over roughly 22 rainy days.
The rhythm of the year is set by latitude (44.5°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.