Weather in Rock Island Arsenal, Illinois
Roses Bloom Along the Shelter Rows. Day 59 of spring. Read this microseason across nine climate regions →
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 10:46 AM
- Moonset
- 1:47 AM
- In sign
- ♉︎ Taurus
Roses Bloom Along the Shelter Rows
Rock Island Arsenal at a glance
- Today vs. normal: NaN°F below the seasonal normal for this latitude
- Last frost: April 25 (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
Rock Island Arsenal's warmest month is July (~74°F mean) and its coldest is January (~22°F). Rainfall peaks in June (5.2 inches) and bottoms out in January (1.5 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 22° | 1.5″ | 4 |
| February | 27° | 1.8″ | 4 |
| March | 38° | 2.6″ | 5 |
| April | 50° | 3.8″ | 7 |
| May | 62° | 5.1″ | 8 |
| June | 71° | 5.2″ | 8 |
| July | 74° | 4.2″ | 6 |
| August | 73° | 4.0″ | 6 |
| September | 66° | 3.3″ | 5 |
| October | 53° | 2.9″ | 5 |
| November | 39° | 2.3″ | 5 |
| December | 28° | 2.0″ | 5 |
Frequently asked
- When does it freeze in Rock Island Arsenal?
- Rock Island Arsenal's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Rock Island Arsenal?
- June is the wettest month with about 5.2 inches of rain on average; the city receives roughly 39 inches annually.
- What is the warmest month in Rock Island Arsenal?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in Rock Island Arsenal?
- January is typically coldest, averaging about 22°F.
- When can I start a vegetable garden in Rock Island Arsenal?
- 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 Rock Island Arsenal get?
- Rock Island Arsenal averages about 67 rainy days per year.
- What hardiness zone is Rock Island Arsenal?
- Rock Island Arsenal'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
Rock Island Arsenal, Illinois sits in a warm-summer humid continental climate zone. January means hover near 22°F while July averages 74°F — a 52°F seasonal swing.
Across the year, Rock Island Arsenal receives about 39 inches of precipitation spread over roughly 67 rainy days.
The rhythm of the year is set by latitude (41.5°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.