Keystone, South Dakota Weather
Prairie lightning bugs rise. Day 77 of spring. Read this microseason across nine climate regions →
Keystone weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Light Drizzle12%0.02″71°55°—
- ThursdayJun 4Light Drizzle24%0.02″72°54°+1°
- FridayJun 5Overcast22%—79°56°+7°
- SaturdayJun 6Overcast——92°59°+13°
- SundayJun 7Drizzle31%—91°64°-1°
- MondayJun 8Mostly Clear31%—79°57°-12°
- TuesdayJun 9Overcast18%—96°62°+17°
PM2.5 at 6.8 µg/m³ (AQI 38) with a 0.86 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust. AQI flat over the last 6 hours (within ±3 points).
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 32 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 8 by mid-afternoon.
- Present
- AQI 32
- UV peak
- 0.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 8
PM × Wind × Precip
PM2.5 at 6.8 µg/m³ (AQI 38) with a 0.86 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.86
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
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
- 5:38 AM
- Moonset
- 2:45 PM
- In sign
- ♑︎ Capricorn
Prairie lightning bugs rise
Keystone at a glance
- Today vs. normal: 11°F below the seasonal normal for this latitude
- Last frost: May 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
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 — Keystone
SPC has placed Keystone in the Slight Risk category for severe thunderstorms tomorrow.
- TODAYNONENo severe risk
- TOMORROWSLGTSlight Risk
- DAY 3TSTMGeneral Thunderstorms
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.