Colwyn, Pennsylvania Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
Colwyn weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——90°59°—
- FridayJun 5Overcast——95°65°+5°
- SaturdayJun 6Overcast28%—91°68°-4°
- SundayJun 7Light Showers36%—88°68°-3°
- MondayJun 8Overcast14%—80°63°-8°
- TuesdayJun 9Overcast——87°60°+7°
- WednesdayJun 10Partly Cloudy——91°66°+4°
PM2.5 at 7.6 µg/m³ (AQI 42) with a 0.92 fine-to-coarse ratio and 4 mph wind — combustion smoke trapped in calm air, not road dust. 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.
What's driving it
Ozone × UV × Sky
Ozone at AQI 36 now. With UV 3.3 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 16 by mid-afternoon.
- Present
- AQI 36
- UV peak
- 3.3 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 16
PM × Wind × Precip
PM2.5 at 7.6 µg/m³ (AQI 42) with a 0.92 fine-to-coarse ratio and 4 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.92
- 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
- 3:28 AM
- Moonset
- 1:01 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Colwyn at a glance
- Today vs. normal: 12°F below the seasonal normal for this latitude
- Last frost: April 15 (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.
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
Colwyn's warmest month is July (~80°F mean) and its coldest is January (~35°F). Rainfall peaks in August (5.0 inches) and bottoms out in February (3.3 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 35° | 3.6″ | 7 |
| February | 37° | 3.3″ | 6 |
| March | 45° | 4.5″ | 7 |
| April | 56° | 4.0″ | 7 |
| May | 66° | 4.1″ | 8 |
| June | 75° | 4.8″ | 8 |
| July | 80° | 4.8″ | 7 |
| August | 78° | 5.0″ | 7 |
| September | 72° | 4.9″ | 6 |
| October | 60° | 4.2″ | 6 |
| November | 49° | 3.4″ | 6 |
| December | 40° | 4.3″ | 7 |
Regional context
Colwyn sits within a warm-summer humid continental climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Philadelphia, PA, Pittsburgh, PA, Allentown, PA, Harrisburg, PA, Lancaster, PA.
Frequently asked
- When does it freeze in Colwyn?
- Colwyn's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Colwyn?
- August is the wettest month with about 5.0 inches of rain on average; the city receives roughly 51 inches annually.
- What is the warmest month in Colwyn?
- July is typically warmest, averaging about 80°F.
- What is the coldest month in Colwyn?
- January is typically coldest, averaging about 35°F.
- When can I start a vegetable garden in Colwyn?
- 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 Colwyn get?
- Colwyn averages about 82 rainy days per year.
- What hardiness zone is Colwyn?
- Colwyn'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
Colwyn, Pennsylvania sits in a warm-summer humid continental climate zone. January means hover near 35°F while July averages 80°F — a 46°F seasonal swing.
Across the year, Colwyn receives about 51 inches of precipitation spread over roughly 82 rainy days.
The rhythm of the year is set by latitude (39.9°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.