Weather in Union, New Jersey
Roses open along the stoops. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 17Overcast—91°63°
- MondayMay 18Drizzle—86°65°
- TuesdayMay 19Light Drizzle—94°65°
- WednesdayMay 20Drizzle58%92°62°
- ThursdayMay 21Overcast27%75°54°
- FridayMay 22Light Drizzle22%64°49°
- SaturdayMay 23Light Drizzle31%54°49°
- PM 2.5
- 10.6 μg/m³
- PM 10
- 10.8 μg/m³
- NO₂
- 11.2 μg/m³
- Ozone
- 98.0 μg/m³
- UV Index
- 0.0 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 9:42 AM
- Moonset
- 12:35 AM
- In sign
- ♊︎ Gemini
Roses open along the stoops
Union at a glance
- Today vs. normal: 69°F — typical for the season
- Last frost: April 20 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Warm-season window is open
As of May 17, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
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
Union's warmest month is July (~78°F mean) and its coldest is January (~32°F). Rainfall peaks in June (4.9 inches) and bottoms out in February (3.3 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 32° | 3.7″ | 7 |
| February | 34° | 3.3″ | 6 |
| March | 41° | 4.3″ | 7 |
| April | 52° | 4.1″ | 7 |
| May | 63° | 4.4″ | 8 |
| June | 72° | 4.9″ | 7 |
| July | 78° | 4.8″ | 6 |
| August | 76° | 4.4″ | 7 |
| September | 69° | 4.3″ | 6 |
| October | 57° | 4.2″ | 6 |
| November | 46° | 3.6″ | 6 |
| December | 37° | 4.6″ | 8 |
Regional context
Union 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: Trenton, NJ, Newark, NJ, Jersey City, NJ, Paterson, NJ, Elizabeth, NJ.
Frequently asked
- When does it freeze in Union?
- Union's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Union?
- June is the wettest month with about 4.9 inches of rain on average; the city receives roughly 50 inches annually.
- What is the warmest month in Union?
- July is typically warmest, averaging about 78°F.
- What is the coldest month in Union?
- January is typically coldest, averaging about 32°F.
- When can I start a vegetable garden in Union?
- 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 Union get?
- Union averages about 79 rainy days per year.
- What hardiness zone is Union?
- Union'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
Union, New Jersey sits in a warm-summer humid continental climate zone. January means hover near 32°F while July averages 78°F — a 46°F seasonal swing.
Across the year, Union receives about 50 inches of precipitation spread over roughly 79 rainy days.
The rhythm of the year is set by latitude (40.7°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.