Delta, Colorado Weather
Pikas hayfeeding in granite peaks. Day 78 of spring. Read this microseason across nine climate regions →
Delta weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——93°53°—
- FridayJun 5Overcast——95°58°+2°
- SaturdayJun 6Overcast——95°58°0°
- SundayJun 7Overcast——89°57°-6°
- MondayJun 8Overcast——91°55°+2°
- TuesdayJun 9Overcast——95°56°+4°
- WednesdayJun 10Drizzle—0.19″69°55°-26°
Ozone at AQI 68 now. AQI up 30 in the last 6 hours — air quality is degrading. With UV 0.4 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 12 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 68 now. With UV 0.4 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 12 by mid-afternoon.
- Present
- AQI 68
- UV peak
- 0.4 at 1 PM
- Sky at peak
- partly cloudy
- Projected peak
- AQI 12
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
- 6:11 AM
- Moonset
- 4:25 PM
- In sign
- ♒︎ Aquarius
Pikas hayfeeding in granite peaks
Delta at a glance
- Today vs. normal: 12°F above the seasonal normal for this latitude
- Last frost: April 9 (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 — Delta
SPC has placed Delta 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 | 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
Delta's warmest month is July (~72°F mean) and its coldest is December (~28°F). Rainfall peaks in September (1.8 inches) and bottoms out in June (0.5 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 28° | 1.1″ | 4 |
| February | 31° | 0.9″ | 3 |
| March | 40° | 0.8″ | 3 |
| April | 46° | 1.0″ | 3 |
| May | 56° | 1.2″ | 4 |
| June | 66° | 0.5″ | 2 |
| July | 72° | 1.0″ | 4 |
| August | 70° | 1.2″ | 4 |
| September | 62° | 1.8″ | 5 |
| October | 49° | 1.3″ | 4 |
| November | 38° | 0.5″ | 2 |
| December | 28° | 1.1″ | 3 |
Regional context
Delta's baseline climate, derived from NOAA NCEI 1991-2020 normals at the nearest reporting station, swings from a January mean of 28°F to a July mean of 72°F — a 45°F seasonal arc typical of the mid-latitude bands. Annual precipitation runs about 12.5 inches spread across roughly 40 days with measurable rain or snow each year.
Rainfall stays relatively even across the calendar: September tops out at 1.8 inches across 4.8 days with measurable rain, and June settles around 0.5 inches across 1.9 rainy days — a comparatively narrow seasonal range. The temperate, evenly-distributed pattern groups Delta with places like Orchard City, CO, Olathe, CO and Cedaredge, CO, where seasonal storm tracks deliver moisture more uniformly than the continental interior.
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 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 Delta 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: Orchard City, CO, Olathe, CO, Cedaredge, CO, Lazear, CO, Hotchkiss, CO.
Frequently asked
- When does it freeze in Delta?
- Delta's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Delta?
- September is the wettest month with about 1.8 inches of rain on average; the city receives roughly 12 inches annually.
- What is the warmest month in Delta?
- July is typically warmest, averaging about 72°F.
- What is the coldest month in Delta?
- December is typically coldest, averaging about 28°F.
- When can I start a vegetable garden in Delta?
- 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 Delta get?
- Delta averages about 40 rainy days per year.
- What hardiness zone is Delta?
- Delta'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
Delta, Colorado sits in a hot desert climate zone. January means hover near 28°F while July averages 72°F — a 45°F seasonal swing.
Across the year, Delta receives about 12 inches of precipitation spread over roughly 40 rainy days.
The rhythm of the year is set by latitude (38.8°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.