National Harbor, Maryland Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
National Harbor weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Clear——84°53°—
- ThursdayJun 4Overcast——91°58°+7°
- FridayJun 5Overcast——95°63°+4°
- SaturdayJun 6Overcast——95°68°0°
- SundayJun 7Light Showers27%—90°68°-5°
- MondayJun 8Light Drizzle17%—73°59°-17°
- TuesdayJun 9Partly Cloudy12%—83°54°+10°
PM2.5 at 11.0 µg/m³ (AQI 55) with a 0.99 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust. AQI up 17 in the last 6 hours — air quality is degrading.
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 33 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 8 by mid-afternoon.
- Present
- AQI 33
- UV peak
- 0.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 8
PM × Wind × Precip
PM2.5 at 11.0 µg/m³ (AQI 55) with a 0.99 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.99
- 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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 3:32 AM
- Moonset
- 1:11 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
National Harbor at a glance
- Today vs. normal: 6°F below the seasonal normal for this latitude
- Last frost: April 9 (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
National Harbor's warmest month is July (~81°F mean) and its coldest is January (~38°F). Rainfall peaks in July (4.3 inches) and bottoms out in February (2.6 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 38° | 2.9″ | 6 |
| February | 40° | 2.6″ | 5 |
| March | 48° | 3.5″ | 7 |
| April | 58° | 3.2″ | 6 |
| May | 67° | 3.9″ | 7 |
| June | 76° | 4.2″ | 7 |
| July | 81° | 4.3″ | 7 |
| August | 79° | 3.3″ | 6 |
| September | 72° | 3.9″ | 6 |
| October | 61° | 3.7″ | 5 |
| November | 50° | 2.9″ | 5 |
| December | 42° | 3.4″ | 6 |
Regional context
National Harbor 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: Baltimore, MD, Hagerstown, MD, Frederick, MD, Waldorf, MD, Columbia, MD.
Frequently asked
- When does it freeze in National Harbor?
- National Harbor's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in National Harbor?
- July is the wettest month with about 4.3 inches of rain on average; the city receives roughly 42 inches annually.
- What is the warmest month in National Harbor?
- July is typically warmest, averaging about 81°F.
- What is the coldest month in National Harbor?
- January is typically coldest, averaging about 38°F.
- When can I start a vegetable garden in National Harbor?
- 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 National Harbor get?
- National Harbor averages about 72 rainy days per year.
- What hardiness zone is National Harbor?
- National Harbor'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
National Harbor, Maryland sits in a warm-summer humid continental climate zone. January means hover near 38°F while July averages 81°F — a 44°F seasonal swing.
Across the year, National Harbor receives about 42 inches of precipitation spread over roughly 72 rainy days.
The rhythm of the year is set by latitude (38.8°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.