Round Lake Beach, Illinois Weather
Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →
Round Lake Beach weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Light Drizzle66%0.04″81°67°—
- SundayJul 5Overcast18%—79°63°-2°
- MondayJul 6Overcast——76°60°-3°
- TuesdayJul 7Overcast——79°58°+3°
- WednesdayJul 8Overcast15%—81°60°+2°
- ThursdayJul 9Light Drizzle50%0.04″76°63°-5°
- FridayJul 10Overcast43%—77°61°+1°
AQI 39 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 6.6 µg/m³ (AQI 37) with a 0.89 fine-to-coarse ratio and 4 mph wind — combustion smoke trapped in calm air, not road dust.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 10 PM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 35 now. With UV 3.4 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 11 around 1 PM.
- Present
- AQI 35
- UV peak
- 3.4 at 1 PM
- Sky at peak
- partly cloudy
- Projected peak
- AQI 11
PM × Wind × Precip
PM2.5 at 6.6 µg/m³ (AQI 37) with a 0.89 fine-to-coarse ratio and 4 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.89
- Wind
- calm
- 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).








































If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 10:50 PM
- Moonset
- 9:55 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
Round Lake Beach at a glance
- Today vs. normal: 7°F above the seasonal normal for this latitude
- Last frost: April 30 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
16-Day Forecast — Round Lake Beach
- Sat81°67°66%
- Sun79°63°18%
- Mon76°60°1%
- Tue79°58°1%
- Wed81°60°15%
- Thu76°63°50%
- Fri77°61°43%
- Sat82°60°10%
- Sun66°59°8%
- Mon74°55°8%
- Tue76°60°9%
- Wed80°64°26%
- Thu83°66°16%
- Fri84°68°16%
- Sat86°69°20%
- Sun85°69°29%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Round Lake Beach
Right now in the garden
Peak growing season
As of July 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.
SPC Convective Outlook
Storm Prediction Center — Round Lake Beach
SPC includes Round Lake Beach in the general thunderstorm area today — no severe risk, but storms are possible.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Microseason · July 1–5
Cicadas claim the afternoon
Annual cicada buzz begins, peaking in the heat of the day.
Day 185 of 365 · Wedge 37 of 72
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Round Lake Beach peaks at about 75°F in July and bottoms near 22°F in January; May brings the heaviest rain (3.7 inches) and January the least (1.8 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 22° | 1.8″ | 15 |
| February | 24° | 1.9″ | 13 |
| March | 35° | 2.7″ | 15 |
| April | 47° | 3.4″ | 17 |
| May | 57° | 3.7″ | 18 |
| June | 68° | 3.4″ | 15 |
| July | 75° | 2.5″ | 13 |
| August | 74° | 2.8″ | 13 |
| September | 67° | 3.1″ | 14 |
| October | 54° | 2.9″ | 13 |
| November | 39° | 3.2″ | 14 |
| December | 26° | 2.3″ | 13 |
Regional context
Round Lake Beach swings from 22°F in January to 75°F in July (53°F) per NOAA NCEI 1991-2020 normals; precipitation in Round Lake Beach runs about 33.6 inches on roughly 173 measurable days.
Round Lake Beach's precipitation spreads evenly: May peaks at 3.7 inches on 18.0 wet days, while January holds 1.8 inches over 14.6 — no month dominates Round Lake Beach's rain calendar. That lines Round Lake Beach up with places like Round Lake Heights, IL, Venetian Village, IL and Long Lake, IL, fed by overlapping storm tracks.
Once Round Lake Beach passes late-May, overnight freezes fade and kale, peas, spinach, and parsnips can be sown. Heat-demanding starts go out a fortnight on in Round Lake Beach, after the soil warms and cold snaps clear. The season ends by early-October in Round Lake Beach, once hard frosts set back in. Round Lake Beach's low ground holds frost later into spring than Round Lake Beach's benches, which run 3-5 days ahead.
Similar climates: Round Lake Heights, IL, Venetian Village, IL, Long Lake, IL, Hainesville, IL, Lake Villa, IL.
Naturalist notes
Late May brings the return of ruby-throated hummingbirds to Round Lake Beach, their iridescent forms appearing at feeders and flowering trees as spring transitions toward summer.
Spring ephemeral wildflowers like bloodroot and trout lily bloom in early April, completing their life cycles before the forest canopy fully leafs out.
Frequently asked
- When does it freeze in Round Lake Beach?
- Round Lake Beach's last spring frost lands near mid-May, and in Round Lake Beach the first fall frost follows around mid-October.
- What is the rainy season in Round Lake Beach?
- Rainfall in Round Lake Beach peaks in May near 3.7 inches, out of about 34 inches annually.
- What is the warmest month in Round Lake Beach?
- Round Lake Beach peaks in July, when the mean runs near 75°F.
- What is the coldest month in Round Lake Beach?
- January is Round Lake Beach's coldest month, averaging about 22°F.
- When can I start a vegetable garden in Round Lake Beach?
- In Round Lake Beach, sow peas and hardy greens around mid-May; Round Lake Beach's tomatoes and peppers wait two weeks more.
- How many rainy days does Round Lake Beach get?
- Round Lake Beach records around 173 days of measurable precipitation annually.
- What hardiness zone is Round Lake Beach?
- With January around 22°F, Round Lake Beach's zone reflects that minimum — the USDA ZIP map confirms Round Lake Beach's band.
- What is the 10-day forecast for Round Lake Beach?
- Round Lake Beach's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Round Lake Beach?
- See this week's day-by-day rain chances for Round Lake Beach in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Round Lake Beach?
- Current conditions for Round Lake Beach and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Round Lake Beach forecast updated?
- The Round Lake Beach forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Round Lake Beach?
- Today's sunrise and sunset times for Round Lake Beach are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Round Lake Beach?
- The next few days in Round Lake Beach's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Climate
Set in a warm-summer humid continental zone, Round Lake Beach, Illinois swings from 22°F in the heart of winter to 75°F at midsummer — a 53°F arc.
Round Lake Beach sees close to 34 inches of precipitation annually, falling across some 173 wet days.
Round Lake Beach's 53°F range, set by its 42.4°N position, drives frost timing and what thrives in Round Lake Beach.
ZIP codes in Round Lake Beach
- 60073