Photo: ECTran71 · Public domainMountlake Terrace has some of the coolest summers among U.S. towns
On a normal January night the air cools to about 36°. Winters are mild: January nights here are milder than in 83% of U.S. towns. Warming shows here too: 1.1° more than in 1901–2000, led by January. Comfortable outdoor weather lasts from May to September, with highs of 64–75°.
A year in Mountlake Terrace at a glance
Each month’s typical high and low, and what it brings.
What stands out about Mountlake Terrace’s climate
Compared with towns across the U.S., with Mountlake Terrace’s place in Washington beside it.
What a year in Mountlake Terrace feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 259 frost-free days a year
In half of years the last 32° night comes by March 8 and the first by November 23. Frost and day counts come from NOAA’s station at Seattle Sand Pt Wsfo, WA, 8 miles from the town’s center, 360 ft lower.
The 2023 USDA map puts Mountlake Terrace’s center in zone 9a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 21°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 4 inches of snow a winter
Snow, measured at Seattle Sand Pt Wsfo, WA, falls mostly in December. Precipitation (rain plus melted snow) adds up to 38 inches a year; December is the wettest month and July the driest. Rain or snow falls on about 163 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Mountlake Terrace
96% 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 Seattle Sand Pt Wsfo, WA.
Living with Mountlake Terrace’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
259 frost-free days in zone 9a. The last frost comes by Mar 8 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 23.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 7.7 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Mountlake Terrace from natural hazards, earthquakes are the largest share (80%); heat waves, cold waves, winter storms and ice storms together are 4%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Mountlake Terrace and its neighbors
Every town next door is within a degree of Mountlake Terrace in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Mountlake Terrace’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 |
|---|---|---|---|---|
| Mountlake Terrace, WA | 36° | 75° | 38" | 3.8" |
| Fairfax, CA | 41° | 76° | 38" | 0.0" |
| West Haven-Sylvan, OR | 36° | 80° | 44" | 3.6" |
| Nantucket, MA | 26° | 76° | 44" | 25" |
| Springs, NY | 24° | 80° | 44" | 27" |
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 Mountlake Terrace averaged 1.1° warmer than the 1900s. The biggest change is in January (+2.4°).
A smaller shift than in 71% 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 Mountlake Terrace compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Mountlake Terrace’s place among Washington’s.
Mountlake Terrace weather by month
Highs, lows and precipitation from NOAA’s grid at Mountlake Terrace’s center; snow, wet days and snow on the ground from Seattle Sand Pt Wsfo, WA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 46° | 36° | 4.9" | 0.9" | 19 | 1 | 37° – 46° |
| February | 49° | 36° | 3.6" | 1.0" | 16 | 1 | 35° – 47° |
| March | 53° | 38° | 4.2" | 0.0" | 18 | 0 | 41° – 50° |
| April | 58° | 41° | 3.0" | 0.0" | 16 | 0 | 45° – 55° |
| May | 64° | 47° | 2.2" | 0.0" | 12 | 0 | 51° – 60° |
| June | 69° | 51° | 1.7" | 0.0" | 11 | 0 | 57° – 65° |
| July | 75° | 55° | 0.8" | 0.0" | 5 | 0 | 61° – 69° |
| August | 75° | 55° | 1.0" | 0.0" | 6 | 0 | 61° – 67° |
| September | 70° | 51° | 1.7" | 0.0" | 9 | 0 | 57° – 63° |
| October | 59° | 45° | 3.8" | 0.0" | 15 | 0 | 49° – 57° |
| November | 51° | 39° | 5.3" | 0.2" | 19 | 0 | 41° – 50° |
| December | 45° | 35° | 5.4" | 1.7" | 20 | 1 | 36° – 43° |
| Year | 59° | 44° | 37.6" | 3.8" | 163 | 2 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 35° to 47°. September is the most reliable, staying within 6°.
Where Mountlake Terrace’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 Mountlake Terrace’s center.
- Snow: Seattle Sand Pt Wsfo, WA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Seattle Sand Pt Wsfo, WA, 8 miles from the town’s center, 360 ft lower; 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 Mountlake Terrace’s climate
What is the weather like in Mountlake Terrace?
A typical July afternoon reaches 75°, a January night drops to 36°, and about 4 inches of snow falls in a normal winter. Milder January nights than 83% of U.S. towns; cooler July afternoons than 98% of U.S. towns.
How cold does it get in Mountlake Terrace in winter?
December nights average 35°. About 25 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 36°.
How much snow does Mountlake Terrace get?
About 3.8 inches in a normal winter at Seattle Sand Pt Wsfo, WA, most of it in December, with snow on the ground about 2 days a year.
How hot does it get in Mountlake Terrace?
July, with a typical high of 75° and a low of 55°. About 2 days a year reach 90° (Seattle Sand Pt Wsfo, WA).
When is the first and last frost in Mountlake Terrace?
In half of years the last spring frost (32°) comes by March 8 and the first fall frost by November 23, about 259 frost-free days, at Seattle Sand Pt Wsfo, WA.
What growing zone is Mountlake Terrace in?
Zone 9a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 21°.
What is the best time of year to visit Mountlake Terrace?
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 Mountlake Terrace getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 71% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Mountlake Terrace.
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.