All Countries
Mountainside, NJ
Full City Profile · New Jersey · Union County County
3.9
/5.0
B+
Good
6,967
Population
1,742/sq mi density
$210,100
Median Income
$86,949 per capita
$755,600
Home Value
$1,033,256 Zillow
$3,501
Median Rent
51.0% income on rent
55°F
Avg Temperature
271 sunny days/yr
44
Violent Crime/100K
755 property/100K
B+
Overall
3.9 / 5.0
Good overall score based on economy, affordability, safety and education
A+
Economy
5.0 / 5.0
$210,100 median income, 1.3% unemployment
A+
Affordability
4.7 / 5.0
$755,600 home value, $3,501/mo rent
F
Safety
1.0 / 5.0
44 violent crimes/100K
A+
Education
5.0 / 5.0
66.2% bachelor's degree or higher
Mountainside experiences four distinct seasons with an average annual temperature of 55°F (13°C). Winters average 33°F in January while summers reach 77°F in July. The area gets 271 sunny days per year. Annual precipitation totals 50.4 inches. The area receives 26.3 inches of snow annually. Air quality is rated Good with a median AQI of 39.
Temperature
33°F Jan (0°C)
77°F Jul (25°C)
| Annual Average | 54.6°F |
| 1% above US avg | |
| January Average | 33°F (0°C) |
| July Average | 77°F (25°C) |
| Sunny Days | 271 days/yr |
Geography
| Elevation | 231 ft (70 m) |
| Area | 4.1 sq mi (10.5 km²) |
| Population Density | 1,742/sq mi |
| Coordinates | 40.6807°N, 74.3603°W |
| Timezone | America/New_York |
| County | Union County County |
| Nearest Airport | Newark Liberty International (EWR) 10 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 39.0 |
| Rating | Good |
Air Pollutants (EPA 2023)
| NO₂ (Nitrogen Dioxide) | 26.6 ppb |
| SO₂ (Sulfur Dioxide) | 0.74 ppb |
| CO (Carbon Monoxide) | 0.42 ppm |
| PM2.5 (Fine Particles) | 9.8 μg/m³ |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 95.5 / 100 |
| Social Vulnerability | 55.8 / 100 |
| Community Resilience | 30.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Relatively Moderate |
| Earthquake | Relatively Moderate |
| Wildfire | Very Low |
| Flood | Relatively High |
| Hail | Very Low |
| Strong Wind | Very High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Very High |
| Lightning | Very High |
| Ice Storm | Very High |
| Drought | Very Low |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
| Coastal Flood | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Tsunami History
3 tsunamis recorded within 500 km. Highest wave on record: 0.3 m (1 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1964 | LONG ISLAND, NY | Meteorological | 0.3 m | — | 107 km |
| 1895 | HIGH BRIDGE, NJ | Earthquake | — | — | 44 km |
| 1840 | PHILADELPHIA, PENNSYLVANIA | Earthquake | — | — | 121 km |
Source: NOAA/NCEI Historical Tsunami Database. Sorted by wave height.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 33°F (0°C) | 3.9 in | |
| February | 31°F (-1°C) | 3.1 in | Coldest, Driest |
| March | 40°F (4°C) | 4.1 in | |
| April | 50°F (10°C) | 4.3 in | |
| May | 60°F (16°C) | 4.7 in | |
| June | 69°F (20°C) | 4.2 in | |
| July | 77°F (25°C) | 5.0 in | Warmest, Wettest |
| August | 72°F (22°C) | 4.4 in | |
| September | 65°F (18°C) | 4.6 in | |
| October | 53°F (12°C) | 3.9 in | |
| November | 44°F (7°C) | 4.3 in | |
| December | 34°F (1°C) | 3.8 in |
Mountainside has a seasonal temperature swing of 46°F / from 31°F in February to 77°F in July. Total annual precipitation is 50.4 inches, with July being the wettest month (5.0") and February the driest (3.1").