Crystal Lake weather in April
In April, Crystal Lake sees average daytime highs of 57°F and overnight lows near 39°F, with 4.3 in of precipitation across 12.3 wet days and about 13.1 hours of daylight. It is the 7th-warmest and 2nd-wettest month of the year here.
Highs climb over the month, from about 53°F in the first days to 61°F by the end. The sky is clear or mostly clear about 23% of the time in April, and the air most often feels dry.
Daylight stretches from about 12 h 24 min at the start of April to 13 h 48 min by month's end. Set against the rest of the year, April is Crystal Lake's 10th-clearest and 1st-windiest month. For the whole year in context, see Crystal Lake's year-round climate.
- Daytime high
- 57°
- 7th warmest
- Overnight low
- 39°
- 6th coldest
- Precipitation
- 4.3 in
- 12.3 wet days
- Daylight
- 13 h 06 min
- 5:19 AM – 6:28 PM
- Cloud cover
- 67%
- 10th clearest
- Wind
- 9 mph
- 1st windiest
- Solar energy
- 4.94 kWh/m²
- Travel score
- 3.7
- out of 10
Crystal Lake is city in McHenry County, Illinois, USA.
- Density
- 780/km²
- people per km²
- Founded
- 1914
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in April
Highs climb over the month, from about 53°F in the first days to 61°F by the end.
A typical April day in Crystal Lake reaches about 57°F in the afternoon and slips back to 39°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 43°F and 72°F. Set against its neighbours, April runs about 12°F warmer than March and about 11°F cooler than May.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 52 | 52 | 53 | 53 | 53 | 54 | 54 | 54 | 55 | 55 | 55 | 56 | 56 | 57 | 57 | 57 | 58 | 58 | 58 | 59 | 59 | 59 | 60 | 60 | 60 | 60 | 61 | 61 | 62 | 62 |
| Avg low (°F) | 35 | 35 | 35 | 36 | 36 | 36 | 37 | 37 | 37 | 37 | 38 | 38 | 38 | 39 | 39 | 40 | 40 | 40 | 40 | 41 | 41 | 42 | 42 | 42 | 42 | 43 | 43 | 44 | 44 | 44 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| 1 | 52 | 35 |
| 2 | 52 | 35 |
| 3 | 53 | 35 |
| 4 | 53 | 36 |
| 5 | 53 | 36 |
| 6 | 54 | 36 |
| 7 | 54 | 37 |
| 8 | 54 | 37 |
| 9 | 55 | 37 |
| 10 | 55 | 37 |
| 11 | 55 | 38 |
| 12 | 56 | 38 |
| 13 | 56 | 38 |
| 14 | 57 | 39 |
| 15 | 57 | 39 |
| 16 | 57 | 40 |
| 17 | 58 | 40 |
| 18 | 58 | 40 |
| 19 | 58 | 40 |
| 20 | 59 | 41 |
| 21 | 59 | 41 |
| 22 | 59 | 42 |
| 23 | 60 | 42 |
| 24 | 60 | 42 |
| 25 | 60 | 42 |
| 26 | 60 | 43 |
| 27 | 61 | 43 |
| 28 | 61 | 44 |
| 29 | 62 | 44 |
| 30 | 62 | 44 |
How April really feels in Crystal Lake
Once humidity and wind are folded in, April averages 0 days that feel above 90°F and 12 that feel at or below 32°F — the comfort signal a plain temperature reading hides.
The story in April is cold — wind chill drags the overnight "feels like" below the raw low.
Crystal Lake weather by month
How April compares with the rest of the year at a glance. April is the 7th-warmest and 2nd-wettest month here — the current month is highlighted below.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 30° / 17° | 2.0 | 7.9 | 6 | 9.3 | 0.0 |
| Feb | 34° / 20° | 1.9 | 7 | 5.2 | 10.3 | 0.0 |
| Mar | 45° / 29° | 2.5 | 9.7 | 3.3 | 11.6 | 1.1 |
| Apr | 57° / 39° | 4.3 | 12.3 | 1.1 | 13.1 | 3.7 |
| May | 68° / 50° | 4.3 | 12.2 | 0 | 14.4 | 5.9 |
| Jun | 78° / 61° | 3.8 | 11.8 | 0 | 15 | 6.4 |
| Jul | 82° / 65° | 3.4 | 10.4 | 0 | 14.8 | 6.4 |
| Aug | 80° / 63° | 3.6 | 10.6 | 0 | 13.7 | 6.6 |
| Sep | 73° / 55° | 3.0 | 8.8 | 0 | 12.3 | 7.0 |
| Oct | 60° / 44° | 3.0 | 8.7 | 0.2 | 10.8 | 5.0 |
| Nov | 46° / 33° | 2.4 | 7.8 | 1.6 | 9.6 | 1.4 |
| Dec | 35° / 22° | 2.1 | 8 | 4.6 | 9 | 0.0 |
Cloud cover in April
The sky is clear or mostly clear about 23% of the time in April.
Beyond those clear spells, partly cloudy skies cover about 13% of April, with mostly cloudy or overcast conditions the remaining 65%.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 32 | 32 | 32 | 33 | 32 | 32 | 33 | 33 | 33 | 35 | 35 | 35 | 36 | 36 | 37 | 37 | 38 | 38 | 38 | 38 | 38 | 37 | 37 | 37 | 37 | 36 | 36 | 36 | 36 | 36 |
| Cloudier (%) | 68 | 68 | 68 | 67 | 68 | 68 | 67 | 67 | 67 | 65 | 65 | 65 | 64 | 64 | 63 | 63 | 62 | 62 | 62 | 62 | 62 | 63 | 63 | 63 | 63 | 64 | 64 | 64 | 64 | 64 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 32 | 68 |
| 2 | 32 | 68 |
| 3 | 32 | 68 |
| 4 | 33 | 67 |
| 5 | 32 | 68 |
| 6 | 32 | 68 |
| 7 | 33 | 67 |
| 8 | 33 | 67 |
| 9 | 33 | 67 |
| 10 | 35 | 65 |
| 11 | 35 | 65 |
| 12 | 35 | 65 |
| 13 | 36 | 64 |
| 14 | 36 | 64 |
| 15 | 37 | 63 |
| 16 | 37 | 63 |
| 17 | 38 | 62 |
| 18 | 38 | 62 |
| 19 | 38 | 62 |
| 20 | 38 | 62 |
| 21 | 38 | 62 |
| 22 | 37 | 63 |
| 23 | 37 | 63 |
| 24 | 37 | 63 |
| 25 | 37 | 63 |
| 26 | 36 | 64 |
| 27 | 36 | 64 |
| 28 | 36 | 64 |
| 29 | 36 | 64 |
| 30 | 36 | 64 |
Chance of precipitation in April
Crystal Lake gets around 4.3 in of rain and snow over 12.3 wet days in April. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable precipitation averages around 40% and peaks near 42% on the wettest days, and about 1 day brings snow.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 37 | 37 | 38 | 38 | 38 | 39 | 39 | 39 | 39 | 40 | 40 | 41 | 41 | 41 | 41 | 41 | 41 | 42 | 42 | 42 | 42 | 42 | 42 | 42 | 42 | 42 | 41 | 41 | 41 | 41 |
| Snow chance (%) | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 4 | 4 | 3 | 3 | 3 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Rain chance (%) | Snow chance (%) | |
|---|---|---|
| 1 | 37 | 5 |
| 2 | 37 | 5 |
| 3 | 38 | 5 |
| 4 | 38 | 5 |
| 5 | 38 | 5 |
| 6 | 39 | 5 |
| 7 | 39 | 5 |
| 8 | 39 | 5 |
| 9 | 39 | 5 |
| 10 | 40 | 5 |
| 11 | 40 | 5 |
| 12 | 41 | 5 |
| 13 | 41 | 5 |
| 14 | 41 | 5 |
| 15 | 41 | 4 |
| 16 | 41 | 4 |
| 17 | 41 | 4 |
| 18 | 42 | 3 |
| 19 | 42 | 3 |
| 20 | 42 | 3 |
| 21 | 42 | 2 |
| 22 | 42 | 2 |
| 23 | 42 | 2 |
| 24 | 42 | 1 |
| 25 | 42 | 1 |
| 26 | 42 | 1 |
| 27 | 41 | 1 |
| 28 | 41 | 1 |
| 29 | 41 | 1 |
| 30 | 41 | 1 |
Humidity in April
Most of April feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, April lands in the dry band about 97% of days. It rarely turns muggy — the humid and sticky bands barely register.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 98 | 98 | 98 | 98 | 98 | 98 | 98 | 98 | 98 | 98 | 97 | 97 | 97 | 97 | 97 | 97 | 96 | 96 | 96 | 97 | 97 | 97 | 96 | 96 | 96 | 96 | 95 | 94 | 93 | 93 |
| Comfortable (%) | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 5 | 5 | 6 | 6 |
| Humid (%) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 |
| Dry (%) | Comfortable (%) | Humid (%) | |
|---|---|---|---|
| 1 | 98 | 2 | 0 |
| 2 | 98 | 2 | 0 |
| 3 | 98 | 2 | 0 |
| 4 | 98 | 2 | 0 |
| 5 | 98 | 2 | 0 |
| 6 | 98 | 2 | 0 |
| 7 | 98 | 2 | 0 |
| 8 | 98 | 2 | 0 |
| 9 | 98 | 2 | 0 |
| 10 | 98 | 2 | 0 |
| 11 | 97 | 2 | 1 |
| 12 | 97 | 2 | 1 |
| 13 | 97 | 2 | 1 |
| 14 | 97 | 2 | 1 |
| 15 | 97 | 2 | 1 |
| 16 | 97 | 2 | 1 |
| 17 | 96 | 3 | 1 |
| 18 | 96 | 3 | 1 |
| 19 | 96 | 3 | 1 |
| 20 | 97 | 3 | 0 |
| 21 | 97 | 3 | 0 |
| 22 | 97 | 3 | 0 |
| 23 | 96 | 4 | 0 |
| 24 | 96 | 4 | 0 |
| 25 | 96 | 4 | 0 |
| 26 | 96 | 4 | 0 |
| 27 | 95 | 5 | 0 |
| 28 | 94 | 5 | 1 |
| 29 | 93 | 6 | 1 |
| 30 | 93 | 6 | 1 |
Wind in April
Winds average 9 mph in April, the windiest month of the year.
Across April, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 8 |
| Feels | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze |
| Wind speed (mph) | Feels | |
|---|---|---|
| 1 | 9 | light breeze |
| 2 | 9 | light breeze |
| 3 | 9 | light breeze |
| 4 | 9 | light breeze |
| 5 | 9 | light breeze |
| 6 | 9 | light breeze |
| 7 | 9 | light breeze |
| 8 | 9 | light breeze |
| 9 | 9 | light breeze |
| 10 | 9 | light breeze |
| 11 | 9 | light breeze |
| 12 | 9 | light breeze |
| 13 | 9 | light breeze |
| 14 | 9 | light breeze |
| 15 | 9 | light breeze |
| 16 | 9 | light breeze |
| 17 | 9 | light breeze |
| 18 | 9 | light breeze |
| 19 | 9 | light breeze |
| 20 | 9 | light breeze |
| 21 | 9 | light breeze |
| 22 | 9 | light breeze |
| 23 | 9 | light breeze |
| 24 | 9 | light breeze |
| 25 | 9 | light breeze |
| 26 | 9 | light breeze |
| 27 | 9 | light breeze |
| 28 | 9 | light breeze |
| 29 | 9 | light breeze |
| 30 | 8 | light breeze |
Sunrise & sunset in April
Daylight runs from about 12 h 24 min at the start of April to 13 h 48 min by month's end. The lit band spans sunrise to sunset each day.
Days grow by about 84 minutes over April. Sunrise moves from 5:45 AM to 4:58 AM, and sunset from 6:11 PM to 6:44 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 12.4 | 12.5 | 12.5 | 12.6 | 12.6 | 12.7 | 12.7 | 12.8 | 12.8 | 12.9 | 12.9 | 13.0 | 13.0 | 13.0 | 13.1 | 13.1 | 13.2 | 13.2 | 13.3 | 13.3 | 13.4 | 13.4 | 13.5 | 13.5 | 13.6 | 13.6 | 13.6 | 13.7 | 13.7 | 13.8 |
| Sunrise (AM) | 5:45 | 5:43 | 5:42 | 5:40 | 5:38 | 5:36 | 5:35 | 5:33 | 5:31 | 5:29 | 5:28 | 5:26 | 5:24 | 5:23 | 5:21 | 5:19 | 5:18 | 5:16 | 5:14 | 5:13 | 5:11 | 5:10 | 5:08 | 5:06 | 5:05 | 5:03 | 5:02 | 5:00 | 4:59 | 4:58 |
| Sunset (PM) | 6:11 | 6:12 | 6:13 | 6:14 | 6:15 | 6:16 | 6:18 | 6:19 | 6:20 | 6:21 | 6:22 | 6:23 | 6:24 | 6:25 | 6:27 | 6:28 | 6:29 | 6:30 | 6:31 | 6:32 | 6:33 | 6:35 | 6:36 | 6:37 | 6:38 | 6:39 | 6:40 | 6:41 | 6:43 | 6:44 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 12.4 | 5:45 | 6:11 |
| 2 | 12.5 | 5:43 | 6:12 |
| 3 | 12.5 | 5:42 | 6:13 |
| 4 | 12.6 | 5:40 | 6:14 |
| 5 | 12.6 | 5:38 | 6:15 |
| 6 | 12.7 | 5:36 | 6:16 |
| 7 | 12.7 | 5:35 | 6:18 |
| 8 | 12.8 | 5:33 | 6:19 |
| 9 | 12.8 | 5:31 | 6:20 |
| 10 | 12.9 | 5:29 | 6:21 |
| 11 | 12.9 | 5:28 | 6:22 |
| 12 | 13.0 | 5:26 | 6:23 |
| 13 | 13.0 | 5:24 | 6:24 |
| 14 | 13.0 | 5:23 | 6:25 |
| 15 | 13.1 | 5:21 | 6:27 |
| 16 | 13.1 | 5:19 | 6:28 |
| 17 | 13.2 | 5:18 | 6:29 |
| 18 | 13.2 | 5:16 | 6:30 |
| 19 | 13.3 | 5:14 | 6:31 |
| 20 | 13.3 | 5:13 | 6:32 |
| 21 | 13.4 | 5:11 | 6:33 |
| 22 | 13.4 | 5:10 | 6:35 |
| 23 | 13.5 | 5:08 | 6:36 |
| 24 | 13.5 | 5:06 | 6:37 |
| 25 | 13.6 | 5:05 | 6:38 |
| 26 | 13.6 | 5:03 | 6:39 |
| 27 | 13.6 | 5:02 | 6:40 |
| 28 | 13.7 | 5:00 | 6:41 |
| 29 | 13.7 | 4:59 | 6:43 |
| 30 | 13.8 | 4:58 | 6:44 |
Solar energy in April
Average shortwave solar energy reaching the ground each day in April, about 4.94 kWh/m².
For context, solar energy here swings from a low near 1.6 kWh/m² to a high of 6.32 kWh/m² in June across the year — April's 4.94 kWh/m² falls in the middle.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.5 | 4.5 | 4.5 | 4.6 | 4.6 | 4.6 | 4.7 | 4.7 | 4.7 | 4.8 | 4.8 | 4.8 | 4.9 | 4.9 | 5.0 | 5.0 | 5.0 | 5.0 | 5.1 | 5.1 | 5.1 | 5.2 | 5.2 | 5.2 | 5.2 | 5.3 | 5.3 | 5.3 | 5.3 | 5.3 |
| Level | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 4.5 | Bright |
| 2 | 4.5 | Bright |
| 3 | 4.5 | Bright |
| 4 | 4.6 | Bright |
| 5 | 4.6 | Bright |
| 6 | 4.6 | Bright |
| 7 | 4.7 | Bright |
| 8 | 4.7 | Bright |
| 9 | 4.7 | Bright |
| 10 | 4.8 | Bright |
| 11 | 4.8 | Bright |
| 12 | 4.8 | Bright |
| 13 | 4.9 | Bright |
| 14 | 4.9 | Bright |
| 15 | 5.0 | Bright |
| 16 | 5.0 | Bright |
| 17 | 5.0 | Bright |
| 18 | 5.0 | Bright |
| 19 | 5.1 | Bright |
| 20 | 5.1 | Bright |
| 21 | 5.1 | Bright |
| 22 | 5.2 | Bright |
| 23 | 5.2 | Bright |
| 24 | 5.2 | Bright |
| 25 | 5.2 | Bright |
| 26 | 5.3 | Bright |
| 27 | 5.3 | Bright |
| 28 | 5.3 | Bright |
| 29 | 5.3 | Bright |
| 30 | 5.3 | Bright |
Is April a good time to visit Crystal Lake?
Our two travel scores rate April for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
April is a weaker month for outdoor sightseeing in Crystal Lake.
What to pack for Crystal Lake in April
From April's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In April, Crystal Lake sees daytime highs around 57°F and nights near 39°F. Worth packing: a warm layer, rain gear and sun protection. About 12 days see rain.
Sea temperature near Crystal Lake in April
The nearest coast averages about 38°F in April — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 24 mi away) is warmest in August at about 71°F and coldest in March near 36°F.
It's comfortable for a long swim from Jul 18 to Sep 8 — about 1.7 months when the water holds above 68°F.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 38 | 36 | 36 | 38 | 43 | 55 | 68 | 71 | 67 | 57 | 47 | 42 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Refreshing | Refreshing | Cool | Bracing | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 38 | Bracing |
| Feb | 36 | Bracing |
| Mar | 36 | Bracing |
| Apr | 38 | Bracing |
| May | 43 | Bracing |
| Jun | 55 | Bracing |
| Jul | 68 | Refreshing |
| Aug | 71 | Refreshing |
| Sep | 67 | Cool |
| Oct | 57 | Bracing |
| Nov | 47 | Bracing |
| Dec | 42 | Bracing |
UV index in Crystal Lake in April
Clear-sky midday UV in April peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Crystal Lake peaks around June 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 2 | 4 | 6 | 8 | 9 | 8 | 8 | 6 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | High | Very high | Very high | Very high | Very high | High | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Low |
| Feb | 2 | Moderate |
| Mar | 4 | Moderate |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 9 | Very high |
| Jul | 8 | Very high |
| Aug | 8 | Very high |
| Sep | 6 | High |
| Oct | 3 | Moderate |
| Nov | 2 | Moderate |
| Dec | 1 | Low |
Air quality in Crystal Lake in April
Average fine-particle pollution (PM2.5) through the year — so you can see where April falls, not just the annual average.
Air quality in Crystal Lake is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (October, 9 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 12 | 15 | 16 | 14 | 15 | 16 | 17 | 16 | 13 | 9 | 10 | 11 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 12 | Moderate |
| Feb | 15 | Moderate |
| Mar | 16 | Moderate |
| Apr | 14 | Moderate |
| May | 15 | Moderate |
| Jun | 16 | Moderate |
| Jul | 17 | Moderate |
| Aug | 16 | Moderate |
| Sep | 13 | Moderate |
| Oct | 9 | Good |
| Nov | 10 | Good |
| Dec | 11 | Good |
Where is Crystal Lake?
Crystal Lake sits at 42.2°N, 88.3°W, 915 ft above sea level, in United States. The nearest listed city is Lake in the Hills, 4.3 mi away.
Topography around Crystal Lake
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Crystal Lake.
Within 2 miles, the terrain around Crystal Lake has only modest variations in elevation — a maximum elevation change of 171 ft around an average of 906 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 322 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 787 ft.
The land around Crystal Lake is covered by trees (47%) and artificial surfaces (27%) within 2 miles, trees (39%) and grassland (26%) within 10 miles, and cropland (38%) and trees (21%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Crystal Lake (42.2411°, -88.3162°, elevation 915 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).