Newcastle, WA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Newcastle, a city in King County, Washington.
Today
85°F
Areas Of Smoke
Areas of smoke after 9am. Sunny, with a high near 85. North wind 3 to 7 mph.
7-day forecast for Newcastle
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 85°F | Areas Of Smoke | 3 to 7 mph N | 0% |
| Tonight | 59°F | Areas Of Smoke | 3 to 7 mph N | 0% |
| Wednesday | 90°F | Patchy Smoke | 6 mph N | 0% |
| Wednesday Night | 61°F | Mostly Clear | 1 to 6 mph NNE | 0% |
| Thursday | 90°F | Sunny | 1 to 5 mph W | 0% |
| Thursday Night | 62°F | Mostly Clear | 5 mph W | 0% |
| Friday | 86°F | Sunny | 3 mph SW | 0% |
| Friday Night | 61°F | Mostly Clear | 2 to 6 mph NNE | 0% |
| Saturday | 83°F | Sunny | 5 mph W | 0% |
| Saturday Night | 58°F | Mostly Clear | 2 to 8 mph NE | 1% |
| Sunday | 78°F | Mostly Sunny | 3 mph WSW | 1% |
| Sunday Night | 58°F | Mostly Clear | 3 mph NNE | 1% |
| Monday | 78°F | Mostly Sunny | 3 mph WNW | 1% |
| Monday Night | 57°F | Partly Cloudy | 5 mph NNE | 0% |
Forecast source: National Weather Service (api.weather.gov) for Newcastle (47.531, -122.166). Updated through the day.
Growing snapshot for Newcastle
Last spring frost
Mar 13
First fall frost
Nov 16
Growing season
248 days
Hardiness zone
8b
More local growing data for Newcastle: nearby ZIP 98006 weather · frost dates · planting calendar · Washington frost dates
Nearby towns & communities
Algona
Ames Lake
Auburn
Baring
Beaux Arts Village
Bellevue
Black Diamond
Bothell
Boulevard Park
Bryn Mawr-Skyway
Burien
Carnation
Clyde Hill
Cottage Lake
Covington
Des Moines
Duvall
East Renton Highlands
Fairwood
Fall City
Federal Way
Greenwater
High Bridge
Hobart
Hunts Point
Index
Issaquah
Kenmore
Kent
Kirkland
Climate data from the nearest NOAA station, Renton Muni Ap, Wa (5.1 mi from Newcastle). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.