Few U.S. towns have cooler summers than Marietta-Alderwood
January nights here settle around 35°. November is the wettest month here, with about 5.3 times the rain of July. Winters are mild: January nights here are milder than in 80% of U.S. towns. Seedlings are safe outdoors from about March 31, with the first autumn frost due around October 30.
A year in Marietta-Alderwood at a glance
Each month’s typical high and low, and what it brings.
What stands out about Marietta-Alderwood’s climate
Compared with towns across the U.S., with Marietta-Alderwood’s place in Washington beside it.
What a year in Marietta-Alderwood feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 211 frost-free days a year
In half of years the last 32° night comes by March 31 and the first by October 30. Frost and day counts come from NOAA’s station at Bellingham International Airport, 0.9 miles from the town’s center, 110 ft higher.
The 2023 USDA map puts Marietta-Alderwood’s center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 16°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
About 3 inches of snow a winter
Snow, measured at Bellingham 3 Ssw, WA, falls mostly in January. Precipitation (rain plus melted snow) adds up to 35 inches a year; November is the wettest month and July the driest. Rain or snow falls on about 166 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Marietta-Alderwood
99% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Bellingham International Airport.
Living with Marietta-Alderwood’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
211 frost-free days in zone 8b. The last frost comes by Mar 31 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 30.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 4.2 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Marietta-Alderwood from natural hazards, earthquakes are the largest share (75%); heat waves, cold waves, winter storms and ice storms together are 8%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Marietta-Alderwood and its neighbors
Every town next door is within a degree of Marietta-Alderwood in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Marietta-Alderwood’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Marietta-Alderwood, WA | 35° | 73° | 35" | 3.4" |
| Kentfield, CA | 42° | 74° | 35" | 0.0" |
| West Haven-Sylvan, OR | 36° | 80° | 44" | 3.6" |
| Nantucket, MA | 26° | 76° | 44" | 25" |
| Makawao, HI | 53° | 75° | 23" | 0.0" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Marietta-Alderwood averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.0°).
A smaller shift than in 51% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Marietta-Alderwood compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Marietta-Alderwood’s place among Washington’s.
Marietta-Alderwood weather by month
Highs, lows and precipitation from NOAA’s grid at Marietta-Alderwood’s center; snow, wet days and snow on the ground from Bellingham 3 Ssw, WA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 46° | 35° | 4.7" | 1.1" | 20 | 1 | 34° – 45° |
| February | 49° | 35° | 2.9" | 0.6" | 16 | 0 | 33° – 47° |
| March | 53° | 38° | 3.3" | 0.5" | 18 | 0 | 40° – 49° |
| April | 58° | 42° | 2.6" | 0.0" | 15 | 0 | 45° – 54° |
| May | 64° | 47° | 2.3" | 0.0" | 11 | 0 | 52° – 58° |
| June | 68° | 51° | 1.7" | 0.0" | 10 | 0 | 56° – 64° |
| July | 73° | 54° | 1.0" | 0.0" | 6 | 0 | 60° – 67° |
| August | 73° | 54° | 1.2" | 0.0" | 6 | 0 | 60° – 66° |
| September | 68° | 50° | 2.0" | 0.0" | 9 | 0 | 56° – 62° |
| October | 59° | 44° | 3.7" | 0.1" | 16 | 0 | 49° – 57° |
| November | 51° | 39° | 5.2" | 0.8" | 20 | 1 | 41° – 50° |
| December | 46° | 35° | 4.4" | 0.3" | 20 | 1 | 35° – 43° |
| Year | 59° | 44° | 35.0" | 3.4" | 166 | 3 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 33° to 47°. September is the most reliable, staying within 6°.
Where Marietta-Alderwood’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Marietta-Alderwood’s center.
- Snow: Bellingham 3 Ssw, WA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Bellingham International Airport, 0.9 miles from the town’s center, 110 ft higher; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Marietta-Alderwood’s climate
What is the weather like in Marietta-Alderwood?
A typical July afternoon reaches 73°, a January night drops to 35°, and about 3 inches of snow falls in a normal winter. Milder January nights than 80% of U.S. towns; cooler July afternoons than all but 128 U.S. towns.
How cold does it get in Marietta-Alderwood in winter?
January nights average 35°. About 59 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 34°.
How much snow does Marietta-Alderwood get?
About 3.4 inches in a normal winter at Bellingham 3 Ssw, WA, most of it in January, with snow on the ground about 3 days a year.
How hot does it get in Marietta-Alderwood?
July, with a typical high of 73°. 90° days are rare: none in a normal year at Bellingham International Airport.
When is the first and last frost in Marietta-Alderwood?
In half of years the last spring frost (32°) comes by March 31 and the first fall frost by October 30, about 211 frost-free days, at Bellingham International Airport.
What growing zone is Marietta-Alderwood in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 16°.
What is the best time of year to visit Marietta-Alderwood?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Marietta-Alderwood getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 51% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Marietta-Alderwood.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.