McHenry W.G. Stratton Lock and Dam, Illinois climate: Climate normals at a NOAA weather station
McHenry W.G. Stratton Lock and Dam's normal year runs from 13°F January nights to 84°F July afternoons, with 37.0 inches of precipitation and 35 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.2°C, January lows of −11°C, July highs of 29°C, 939 mm of precipitation a year.
- NOAA stationMcHenry W.G. Stratton Lock and Dam
- Station IDUSC00115493
- Location42.31°N 88.25°W
- Elevation736 ft (224 m)
On October 23, the normal high in McHenry W.G. Stratton Lock and Dam is 60°F and the normal low 37°F, and the chance of measurable rain or snow is 31%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for McHenry W.G. Stratton Lock and Dam.
- Jan 31° 13°
- Feb 35° 16°
- Mar 46° 26°
- Apr 59° 37°
- May 70° 47°
- Jun 80° 57°
- Jul 84° 62°
- Aug 82° 60°
- Sep 76° 51°
- Oct 63° 40°
- Nov 48° 29°
- Dec 36° 19°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at McHenry W.G. Stratton Lock and Dam each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 13°F. The most precipitation falls in June (4.81 in), the least in February (1.56 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 31°F | 13°F | 21.7°F | 1.65 | 11.0 | 10 | <1 | 29 | 9 h 20 min |
| February | 35°F | 16°F | 25.4°F | 1.56 | 8.9 | 8 | <1 | 26 | 10 h 30 min |
| March | 46°F | 26°F | 35.9°F | 2.21 | 3.9 | 9 | <1 | 23 | 11 h 50 min |
| April | 59°F | 37°F | 47.7°F | 3.63 | 1.0 | 11 | <1 | 9 | 13 h 20 min |
| May | 70°F | 47°F | 58.8°F | 4.47 | 0.0 | 13 | <1 | 1 | 14 h 30 min |
| June | 80°F | 57°F | 68.6°F | 4.81 | 0.0 | 12 | 3 | <1 | 15 h 20 min |
| July | 84°F | 62°F | 72.8°F | 3.80 | 0.0 | 10 | 5 | <1 | 15 h |
| August | 82°F | 60°F | 71.0°F | 3.70 | 0.0 | 10 | 2 | <1 | 14 h |
| September | 76°F | 51°F | 63.6°F | 3.61 | 0.0 | 9 | 1 | <1 | 12 h 30 min |
| October | 63°F | 40°F | 51.3°F | 3.21 | 0.1 | 10 | <1 | 8 | 11 h 10 min |
| November | 48°F | 29°F | 38.7°F | 2.38 | 1.4 | 8 | <1 | 19 | 9 h 50 min |
| December | 36°F | 19°F | 27.6°F | 1.94 | 8.2 | 9 | <1 | 28 | 9 h 10 min |
| Year (annual) | 59°F | 38°F | 48.6°F | 36.97 | 34.5 | 119 | 11 | 144 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −11°C | −5.7°C | 42 mm | 28 cm |
| February | 1°C | −9°C | −3.7°C | 40 mm | 23 cm |
| March | 8°C | −3°C | 2.2°C | 56 mm | 10 cm |
| April | 15°C | 3°C | 8.7°C | 92 mm | 3 cm |
| May | 21°C | 8°C | 14.9°C | 114 mm | 0 cm |
| June | 27°C | 14°C | 20.3°C | 122 mm | 0 cm |
| July | 29°C | 16°C | 22.7°C | 97 mm | 0 cm |
| August | 28°C | 15°C | 21.7°C | 94 mm | 0 cm |
| September | 24°C | 11°C | 17.6°C | 92 mm | 0 cm |
| October | 17°C | 4°C | 10.7°C | 82 mm | 0 cm |
| November | 9°C | −1°C | 3.7°C | 60 mm | 4 cm |
| December | 2°C | −7°C | −2.4°C | 49 mm | 21 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00115493; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at McHenry W.G. Stratton Lock and Dam?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (9).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00115493.
When is the last frost at McHenry W.G. Stratton Lock and Dam?
In McHenry W.G. Stratton Lock and Dam, the last spring frost (32°F) comes after May 1 in half of years and after May 19 in one year in ten; the first autumn frost comes before October 11 in half of years and before September 27 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 11 year in 10 after May 19; 9 in 10 after April 16
- First autumn frost, half of years before
- October 111 year in 10 before September 27; 9 in 10 before October 24
NOAA puts the median frost-free season at 162 days, and the season without a hard freeze (28°F) at 185 days.
A hard freeze (28°F) comes after April 19 in half of springs and before October 22 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts McHenry W.G. Stratton Lock and Dam in zone 5b in ZIP code 60050, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 5b: the coldest night of a typical year reaches −14°F (27 complete years).
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00115493; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at McHenry W.G. Stratton Lock and Dam?
In a normal year in McHenry W.G. Stratton Lock and Dam, 11 days a year reach 90°F, 144 nights fall to 32°F or colder and 119 days bring measurable precipitation.
- Days at 90°F or more
- 11a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 144a normal year
- Days that stay below freezing
- 54high of 32°F or less
- Days with 0.01 inch of precipitation
- 119a normal year
- Days with 1 inch of snow or more
- 11a normal year
The highest temperature in this station's record (since 1992) is 101°F, on July 14, 1995; the lowest is −32°F, on January 31, 2019.
The wettest calendar year on that record is 2019, with 52.74 in; the snowiest season is 1978–79, with 85.2 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00115493; records: ACIS (NOAA Regional Climate Centers), station USC00115493. Records use complete months only; a month missing more than three days is left out.
How sunny is it at McHenry W.G. Stratton Lock and Dam?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds at McHenry W.G. Stratton Lock and Dam, 3.9 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 63% | 1.7 |
| February | 67% | 2.6 |
| March | 67% | 3.6 |
| April | 69% | 4.7 |
| May | 70% | 5.5 |
| June | 76% | 6.1 |
| July | 80% | 6.3 |
| August | 79% | 5.4 |
| September | 78% | 4.3 |
| October | 69% | 2.8 |
| November | 66% | 1.9 |
| December | 61% | 1.4 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does McHenry W.G. Stratton Lock and Dam record?
A normal year at McHenry W.G. Stratton Lock and Dam brings 6,689 heating degree days, 24% more than the median U.S. place (5,373), and 750 cooling degree days, 17% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,891 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,341 | 0 |
| February | 1,109 | 0 |
| March | 902 | 1 |
| April | 525 | 6 |
| May | 239 | 47 |
| June | 49 | 156 |
| July | 9 | 252 |
| August | 14 | 200 |
| September | 121 | 78 |
| October | 434 | 9 |
| November | 788 | 0 |
| December | 1,159 | 0 |
| Year (annual) | 6,689 | 750 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00115493. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Have recent years at McHenry W.G. Stratton Lock and Dam been warmer than normal?
2025 averaged 49.1°F, 0.5°F above the 1991-2020 normal of 48.6°F. 4 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 50.1°F | +1.5°F | 24.50 | 27.1 |
| 2023 | 50.3°F | +1.7°F | 31.05 | 22.7 |
| 2024 | 51.7°F | +3.1°F | 39.32 | 23.8 |
| 2025 | 49.1°F | +0.5°F | 28.46 | 27.5 |
Source: observed years: ACIS, station USC00115493. A year counts only with all twelve months complete.
How does McHenry W.G. Stratton Lock and Dam's climate compare?
McHenry W.G. Stratton Lock and Dam is warmer than 14 of the 144 places with their own NOAA record in Illinois, and wetter than 14. Across the 7,247 U.S. stations with normals, its annual mean of 48.6°F is warmer than 34%.
In the Köppen classification computed from these normals, McHenry W.G. Stratton Lock and Dam is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near McHenry W.G. Stratton Lock and Dam share this climate record?
10 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- McHenry, IL28,825 people · 3 mi NW
- Cary, IL18,031 people · 7 mi S
- Island Lake, IL8,066 people · 3 mi SE
- Volo, IL7,361 people · 5 mi E
- Lakemoor, IL6,451 people · 3 mi NE
- Oakwood Hills, IL2,059 people · 4 mi S
- Prairie Grove, IL1,951 people · 3 mi S
- Port Barrington, IL1,579 people · 5 mi SE
- Holiday Hills, IL606 people · 2 mi SE
- Burtons Bridge, IL180 people · 2 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about McHenry W.G. Stratton Lock and Dam's climate
What is the coldest month at McHenry W.G. Stratton Lock and Dam?
January, with a normal high of 31°F and a normal low of 13°F. The warmest is July (84°F by day, 62°F at night).
Does it snow at McHenry W.G. Stratton Lock and Dam?
Yes: 35 inches in a normal year, falling on 22 days with 0.1 inch or more, the most in January (11.0 inches).
What is the rainiest month at McHenry W.G. Stratton Lock and Dam?
June, with 4.81 in of precipitation in a normal year; the driest is February with 1.56 in.
What plant hardiness zone is McHenry W.G. Stratton Lock and Dam in?
The USDA's 2023 map puts McHenry W.G. Stratton Lock and Dam in zone 5b in ZIP code 60050, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −14°F (27 years, 1991-2020): zone 5b.
How late can frost come at McHenry W.G. Stratton Lock and Dam?
In half of years the last 32°F night comes after May 1; in one year in ten it comes after May 19. Waiting until May 19 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Crystal Lake, IL8 miles from this station, 49.1°F a year
- Mundelein, IL10 miles from this station, 47.9°F a year
- Lake Villa, IL13 miles from this station, 48.6°F a year
- Barrington, IL14 miles from this station, 48.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made