New Castle, Indiana Weather
Fireflies pulse through the magnolias. Day 76 of spring. Read this microseason across nine climate regions →
New Castle weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——80°51°—
- ThursdayJun 4Overcast——83°56°+3°
- FridayJun 5Overcast——79°61°-4°
- SaturdayJun 6Light Showers62%—79°64°0°
- SundayJun 7Drizzle62%—82°67°+3°
- MondayJun 8Drizzle11%—80°63°-2°
- TuesdayJun 9Light Drizzle12%—79°68°-1°
Ozone at AQI 75 now. AQI flat over the last 6 hours (within ±4 points). With UV 8.5 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 85 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 75 now. With UV 8.5 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 85 by mid-afternoon.
- Present
- AQI 75
- UV peak
- 8.5 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 85
PM × Wind × Precip
PM2.5 at 7.1 µg/m³ (AQI 39) with a 0.88 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.88
- Wind
- light
- 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).
The higher the clouds, the finer the weather.
- Moonrise
- 3:33 AM
- Moonset
- 12:39 PM
- In sign
- ♑︎ Capricorn
Fireflies pulse through the magnolias
New Castle at a glance
- Today vs. normal: 4°F above the seasonal normal for this latitude
- Last frost: April 16 (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 3, 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 — New Castle
SPC has placed New Castle 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
New Castle's warmest month is July (~72°F mean) and its coldest is January (~26°F). Rainfall peaks in June (5.3 inches) and bottoms out in February (2.5 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 26° | 3.0″ | 6 |
| February | 29° | 2.5″ | 5 |
| March | 38° | 3.4″ | 7 |
| April | 50° | 4.4″ | 9 |
| May | 61° | 4.8″ | 9 |
| June | 69° | 5.3″ | 9 |
| July | 72° | 4.7″ | 7 |
| August | 71° | 3.4″ | 6 |
| September | 65° | 3.1″ | 6 |
| October | 53° | 3.2″ | 6 |
| November | 41° | 3.5″ | 7 |
| December | 31° | 3.0″ | 7 |
Regional context
New Castle's baseline climate, derived from NOAA NCEI 1991-2020 normals at the nearest reporting station, swings from a January mean of 26°F to a July mean of 72°F — a 46°F seasonal arc typical of the mid-latitude bands. Annual precipitation runs about 44.3 inches spread across roughly 82 days with measurable rain or snow each year.
Rainfall stays relatively even across the calendar: June tops out at 5.3 inches across 8.8 days with measurable rain, and February settles around 2.5 inches across 5.3 rainy days — a comparatively narrow seasonal range. The balanced distribution lines New Castle up with places like Westwood, IN, Greensboro, IN and Mount Summit, IN, all of which run on overlapping storm tracks rather than a single seasonal moisture source.
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-soil crops — tomatoes, peppers, eggplant — wait until soil temperatures reach the mid-50s°F, usually two weeks past the last-frost date. 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 New Castle 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: Westwood, IN, Greensboro, IN, Mount Summit, IN, Spiceland, IN, Millville, IN.
Frequently asked
- When does it freeze in New Castle?
- New Castle's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in New Castle?
- June is the wettest month with about 5.3 inches of rain on average; the city receives roughly 44 inches annually.
- What is the warmest month in New Castle?
- July is typically warmest, averaging about 72°F.
- What is the coldest month in New Castle?
- January is typically coldest, averaging about 26°F.
- When can I start a vegetable garden in New Castle?
- 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 New Castle get?
- New Castle averages about 82 rainy days per year.
- What hardiness zone is New Castle?
- New Castle'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
New Castle, Indiana sits in a humid subtropical climate zone. January means hover near 26°F while July averages 72°F — a 46°F seasonal swing.
Across the year, New Castle receives about 44 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.