Wonder Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wonder Lake State Park clear sky chart from 2005-11-06 to 2025-07-21.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	17% 8% 3 6% 4 4 4 4 5% 7% 38%	119986
	Night	17% 8% 3 6% 4 4 4 3 5% 6% 40%	119122
Transparency	Day	44% 6% 11% 22% 15% 2	123545
	Night	43% 5% 12% 22% 16% 3	123724
Seeing	Day	25% 16% 29% 19% 9% 2	15838
	Night	23% 15% 28% 25% 8% 1	24911

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	12% 7% 3 8% 5% 4 4 4 4 6% 44%	3597
	11th to 20th	Day	14% 9% 3 7% 6% 5% 4 3 4 5% 39%	3570
	21st to end	Day	17% 10% 4 7% 4 4 4 3 4 5% 38%	4190
February	1st to 10th	Day	17% 8% 3 7% 5% 5% 5% 4 5% 6% 35%	1816
	11th to 20th	Day	15% 8% 2 7% 5% 5% 4 4 5% 7% 39%	1948
	21st to end	Day	18% 10% 3 7% 4 4 4 3 5% 5% 38%	1650
March	1st to 10th	Day	22% 8% 2 7% 4 3 4 2 4 5% 39%	4476
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 4 6% 7% 42%	4699
	21st to end	Day	18% 9% 3 7% 4 4 4 3 5% 6% 37%	5969
April	1st to 10th	Day	18% 10% 3 7% 4 4 4 3 6% 6% 35%	2400
	11th to 20th	Day	17% 7% 3 6% 4 4 4 4 5% 7% 38%	2374
	21st to end	Day	19% 6% 2 5% 5% 4 4 3 5% 6% 40%	2465
May	1st to 10th	Day	29% 8% 2 5% 4 4 4 3 5% 8% 26%	5886
	11th to 20th	Day	20% 9% 3 7% 4 4 5% 3 4 6% 35%	6271
	21st to end	Day	21% 8% 2 5% 4 4 4 4 6% 8% 35%	6949
June	1st to 10th	Day	17% 5% 2 5% 4 5% 5% 5% 8% 8% 35%	2800
	11th to 20th	Day	16% 7% 3 6% 5% 4 5% 4 7% 8% 35%	2800
	21st to end	Day	12% 7% 2 7% 5% 5% 6% 4 6% 8% 38%	2800
July	1st to 10th	Day	11% 7% 3 7% 6% 6% 6% 4 6% 9% 35%	4580
	11th to 20th	Day	12% 7% 2 6% 4 5% 6% 4 8% 10% 37%	4580
	21st to end	Day	16% 7% 3 8% 5% 5% 5% 5% 5% 7% 34%	4814
August	1st to 10th	Day	20% 7% 3 6% 5% 5% 5% 4 6% 7% 31%	4258
	11th to 20th	Day	12% 8% 2 6% 4 4 5% 5% 6% 9% 41%	3730
	21st to end	Day	10% 6% 2 6% 4 4 4 4 6% 10% 45%	4180
September	1st to 10th	Day	13% 6% 2 6% 4 4 5% 4 5% 6% 43%	2280
	11th to 20th	Day	12% 5% 3 5% 4 3 4 3 4 7% 50%	2181
	21st to end	Day	16% 7% 2 7% 4 3 4 4 5% 7% 40%	2090
October	1st to 10th	Day	22% 7% 2 5% 4 4 4 3 4 4 41%	2006
	11th to 20th	Day	14% 6% 2 5% 4 4 4 3 6% 7% 45%	1900
	21st to end	Day	21% 6% 2 5% 5% 4 4 4 5% 6% 38%	1905
November	1st to 10th	Day	13% 7% 2 5% 3 4 3 2 4 6% 50%	1761
	11th to 20th	Day	17% 6% 3 5% 3 3 3 2 5% 7% 46%	1800
	21st to end	Day	17% 7% 2 6% 3 3 4 3 5% 6% 42%	1715
December	1st to 10th	Day	15% 9% 3 6% 3 4 4 3 5% 7% 42%	2600
	11th to 20th	Day	21% 8% 2 5% 3 3 3 3 4 6% 43%	2986
	21st to end	Day	18% 10% 4 7% 4 4 3 3 4 6% 36%	3960
January	1st to 10th	Night	13% 6% 2 5% 4 5% 5% 4 6% 7% 44%	6349
	11th to 20th	Night	13% 8% 3 8% 4 3 4 3 5% 6% 42%	6315
	21st to end	Night	16% 9% 3 7% 5% 5% 3 3 5% 6% 38%	6752
February	1st to 10th	Night	16% 10% 3 6% 5% 4 4 3 5% 5% 39%	2582
	11th to 20th	Night	15% 9% 3 6% 4 4 5% 4 6% 6% 38%	2338
	21st to end	Night	18% 7% 3 7% 4 3 4 3 5% 5% 39%	1980
March	1st to 10th	Night	20% 9% 2 5% 3 3 3 3 5% 6% 40%	5364
	11th to 20th	Night	15% 7% 4 7% 4 4 4 3 4 7% 42%	5256
	21st to end	Night	18% 11% 3 6% 4 3 4 3 5% 5% 38%	4962
April	1st to 10th	Night	18% 9% 3 6% 4 5% 5% 4 5% 6% 34%	2000
	11th to 20th	Night	18% 8% 3 6% 5% 5% 4 3 5% 6% 37%	1975
	21st to end	Night	19% 8% 2 6% 4 3 4 3 5% 5% 40%	1932
May	1st to 10th	Night	30% 8% 3 7% 4 4 3 3 4 7% 26%	4054
	11th to 20th	Night	20% 9% 4 7% 4 4 4 3 6% 5% 35%	3651
	21st to end	Night	20% 8% 3 6% 3 4 4 3 5% 7% 36%	3926
June	1st to 10th	Night	17% 6% 3 5% 6% 4 5% 3 5% 7% 40%	1600
	11th to 20th	Night	14% 6% 2 6% 4 3 5% 5% 7% 9% 39%	1600
	21st to end	Night	12% 5% 2 6% 5% 4 5% 3 7% 10% 41%	1600
July	1st to 10th	Night	11% 6% 2 6% 4 6% 5% 5% 7% 8% 38%	2600
	11th to 20th	Night	14% 7% 3 7% 5% 5% 4 5% 6% 9% 36%	2600
	21st to end	Night	17% 9% 2 6% 4 4 5% 4 5% 7% 36%	2739
August	1st to 10th	Night	22% 7% 3 7% 5% 5% 4 4 6% 7% 30%	2638
	11th to 20th	Night	15% 7% 3 6% 4 5% 4 4 5% 8% 40%	3097
	21st to end	Night	12% 6% 1 5% 3 3 3 3 5% 7% 53%	3476
September	1st to 10th	Night	15% 6% 2 6% 4 3 4 3 4 6% 46%	1900
	11th to 20th	Night	13% 5% 2 4 3 3 3 2 5% 7% 53%	1997
	21st to end	Night	17% 6% 3 6% 3 3 3 4 5% 5% 44%	2090
October	1st to 10th	Night	19% 8% 3 6% 3 4 3 3 4 6% 42%	2171
	11th to 20th	Night	15% 5% 2 6% 3 4 3 2 5% 7% 47%	2280
	21st to end	Night	21% 6% 3 6% 3 4 4 3 5% 6% 39%	2693
November	1st to 10th	Night	12% 6% 2 6% 4 3 4 3 5% 6% 48%	2537
	11th to 20th	Night	18% 7% 2 5% 4 3 3 3 4 6% 44%	2600
	21st to end	Night	15% 7% 2 5% 5% 3 4 3 6% 8% 43%	2684
December	1st to 10th	Night	16% 8% 2 6% 4 3 4 3 4 6% 45%	4580
	11th to 20th	Night	24% 9% 2 5% 3 3 4 3 4 4 39%	5208
	21st to end	Night	19% 10% 3 7% 4 3 3 3 4 5% 37%	6996

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 4 9% 29% 14% 3	3598
	11th to 20th	Day	46% 5% 9% 22% 12% 6%	3600
	21st to end	Day	48% 4 8% 23% 16% 1	4190
February	1st to 10th	Day	48% 6% 11% 20% 14% 1	1816
	11th to 20th	Day	44% 6% 10% 22% 16% 2	1957
	21st to end	Day	48% 4 11% 22% 13% 2	1650
March	1st to 10th	Day	48% 4 10% 17% 12% 9%	4479
	11th to 20th	Day	38% 7% 12% 29% 10% 3	4699
	21st to end	Day	46% 5% 8% 13% 21% 6%	5969
April	1st to 10th	Day	48% 6% 8% 21% 14% 3	2400
	11th to 20th	Day	44% 5% 10% 22% 16% 2	2374
	21st to end	Day	44% 6% 10% 21% 17% 3	2465
May	1st to 10th	Day	56% 7% 14% 14% 9% 1	5897
	11th to 20th	Day	50% 6% 11% 20% 13% 1	6275
	21st to end	Day	46% 7% 11% 23% 13% 1	6949
June	1st to 10th	Day	43% 8% 13% 22% 13% 1	2800
	11th to 20th	Day	44% 7% 14% 23% 11% 1	2800
	21st to end	Day	42% 8% 12% 24% 13% 1	2800
July	1st to 10th	Day	43% 9% 11% 21% 15% 1	4510
	11th to 20th	Day	40% 8% 16% 23% 13% 1	4505
	21st to end	Day	48% 7% 11% 18% 15% 1	4661
August	1st to 10th	Day	49% 7% 14% 21% 8%	4244
	11th to 20th	Day	38% 7% 16% 30% 10%	3766
	21st to end	Day	34% 6% 12% 32% 16% 1	4180
September	1st to 10th	Day	40% 6% 11% 24% 18% 1	2280
	11th to 20th	Day	35% 4 9% 25% 25% 2	2181
	21st to end	Day	43% 5% 10% 22% 16% 3	2090
October	1st to 10th	Day	40% 6% 9% 18% 24% 4	3331
	11th to 20th	Day	29% 4 9% 26% 27% 5%	3140
	21st to end	Day	31% 4 15% 25% 22% 4	3117
November	1st to 10th	Day	36% 4 12% 27% 19% 3	1761
	11th to 20th	Day	39% 4 11% 23% 20% 4	1800
	21st to end	Day	41% 4 14% 28% 11% 2	1715
December	1st to 10th	Day	42% 4 15% 28% 11% 1	2600
	11th to 20th	Day	43% 4 15% 21% 15% 2	2986
	21st to end	Day	50% 4 8% 20% 15% 3	3960
January	1st to 10th	Night	37% 5% 11% 27% 18% 2	6349
	11th to 20th	Night	41% 5% 15% 20% 14% 5%	6360
	21st to end	Night	47% 4 10% 18% 17% 4	6752
February	1st to 10th	Night	47% 5% 12% 23% 12% 2	2582
	11th to 20th	Night	44% 5% 10% 18% 19% 4	2340
	21st to end	Night	46% 4 8% 23% 15% 4	1980
March	1st to 10th	Night	44% 5% 11% 18% 15% 7%	5374
	11th to 20th	Night	41% 6% 14% 23% 12% 4	5257
	21st to end	Night	47% 4 7% 14% 23% 5%	4962
April	1st to 10th	Night	48% 6% 10% 19% 14% 3	2000
	11th to 20th	Night	47% 6% 10% 18% 18% 1	1975
	21st to end	Night	45% 5% 8% 22% 17% 3	1932
May	1st to 10th	Night	58% 7% 12% 12% 10% 1	4060
	11th to 20th	Night	49% 7% 12% 17% 13% 2	3652
	21st to end	Night	46% 7% 13% 22% 10% 2	3927
June	1st to 10th	Night	43% 7% 9% 23% 17% 2	1600
	11th to 20th	Night	40% 6% 18% 24% 10% 1	1600
	21st to end	Night	37% 8% 15% 25% 14% 1	1600
July	1st to 10th	Night	40% 10% 15% 19% 15% 2	2560
	11th to 20th	Night	42% 8% 14% 23% 12%	2552
	21st to end	Night	45% 7% 14% 15% 18% 2	2651
August	1st to 10th	Night	52% 8% 14% 18% 8% 1	2628
	11th to 20th	Night	42% 6% 14% 29% 8%	3127
	21st to end	Night	30% 5% 12% 36% 15% 1	3476
September	1st to 10th	Night	40% 5% 10% 28% 17% 1	1900
	11th to 20th	Night	31% 4 11% 26% 26% 2	1997
	21st to end	Night	42% 5% 8% 22% 22% 2	2090
October	1st to 10th	Night	41% 5% 11% 22% 20% 2	3626
	11th to 20th	Night	27% 4 10% 29% 26% 4	3779
	21st to end	Night	34% 4 13% 29% 17% 2	4431
November	1st to 10th	Night	36% 5% 11% 23% 21% 3	2537
	11th to 20th	Night	41% 3 9% 22% 20% 4	2600
	21st to end	Night	39% 5% 13% 30% 12% 1	2684
December	1st to 10th	Night	41% 4 13% 32% 10% 1	4580
	11th to 20th	Night	48% 4 12% 18% 15% 2	5208
	21st to end	Night	48% 5% 9% 18% 16% 4	6996

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	37% 23% 23% 15% 3	200
	11th to 20th	Day	37% 25% 26% 11% 2	200
	21st to end	Day	26% 30% 31% 9% 3 1	270
February	1st to 10th	Day	35% 29% 27% 7% 2	316
	11th to 20th	Day	33% 26% 29% 11% 1	496
	21st to end	Day	35% 21% 29% 12% 3	414
March	1st to 10th	Day	32% 21% 30% 13% 3	500
	11th to 20th	Day	31% 24% 29% 13% 3 1	500
	21st to end	Day	34% 21% 29% 10% 4 2	550
April	1st to 10th	Day	36% 22% 25% 11% 6% 1	500
	11th to 20th	Day	30% 25% 26% 11% 6% 1	492
	21st to end	Day	32% 14% 34% 14% 3 2	500
May	1st to 10th	Day	37% 17% 26% 12% 5% 2	503
	11th to 20th	Day	26% 18% 30% 18% 7% 1	527
	21st to end	Day	22% 12% 28% 25% 10% 3	573
June	1st to 10th	Day	22% 11% 32% 24% 11% 1	530
	11th to 20th	Day	19% 13% 32% 22% 12% 2	530
	21st to end	Day	16% 12% 32% 25% 13% 2	530
July	1st to 10th	Day	17% 7% 30% 29% 13% 3	525
	11th to 20th	Day	12% 7% 31% 31% 15% 3	524
	21st to end	Day	14% 9% 34% 28% 13% 2	532
August	1st to 10th	Day	17% 7% 26% 29% 15% 5%	486
	11th to 20th	Day	15% 7% 27% 29% 15% 6%	479
	21st to end	Day	12% 11% 29% 27% 14% 7%	539
September	1st to 10th	Day	19% 13% 23% 21% 17% 7%	490
	11th to 20th	Day	14% 9% 29% 26% 14% 9%	490
	21st to end	Day	23% 12% 29% 20% 10% 5%	490
October	1st to 10th	Day	29% 12% 24% 17% 14% 4	490
	11th to 20th	Day	19% 20% 29% 21% 9% 2	490
	21st to end	Day	29% 12% 28% 20% 9% 1	442
November	1st to 10th	Day	21% 19% 25% 22% 10% 2	395
	11th to 20th	Day	29% 22% 28% 16% 6% 1	400
	21st to end	Day	28% 22% 27% 17% 5% 1	315
December	1st to 10th	Day	29% 27% 28% 13% 4 1	200
	11th to 20th	Day	39% 23% 28% 10% 2	200
	21st to end	Day	29% 25% 27% 13% 6%	220
January	1st to 10th	Night	25% 20% 34% 18% 3	800
	11th to 20th	Night	28% 20% 28% 21% 3	800
	21st to end	Night	23% 22% 32% 20% 3	880
February	1st to 10th	Night	26% 19% 32% 21% 2	800
	11th to 20th	Night	27% 21% 35% 16% 1	783
	21st to end	Night	29% 21% 30% 17% 3	660
March	1st to 10th	Night	27% 21% 30% 18% 4	800
	11th to 20th	Night	25% 22% 30% 20% 3	800
	21st to end	Night	25% 21% 32% 18% 4	880
April	1st to 10th	Night	28% 20% 31% 17% 4	800
	11th to 20th	Night	25% 18% 31% 21% 5%	791
	21st to end	Night	25% 19% 31% 19% 5%	732
May	1st to 10th	Night	28% 15% 31% 21% 5% 1	600
	11th to 20th	Night	25% 14% 31% 24% 6%	431
	21st to end	Night	20% 7% 27% 35% 10% 1	433
June	1st to 10th	Night	19% 8% 28% 33% 12%	400
	11th to 20th	Night	19% 7% 27% 33% 14% 1	400
	21st to end	Night	15% 5% 25% 43% 12% 1	400
July	1st to 10th	Night	16% 6% 19% 39% 20% 1	390
	11th to 20th	Night	13% 5% 22% 43% 15% 1	388
	21st to end	Night	14% 4 24% 41% 17%	416
August	1st to 10th	Night	12% 3 27% 40% 16% 2	445
	11th to 20th	Night	15% 5% 19% 38% 21% 2	750
	21st to end	Night	18% 4 19% 36% 21% 2	836
September	1st to 10th	Night	17% 6% 26% 33% 14% 3	760
	11th to 20th	Night	16% 7% 24% 30% 18% 4	760
	21st to end	Night	21% 7% 26% 29% 15% 2	760
October	1st to 10th	Night	25% 10% 23% 27% 14% 2	760
	11th to 20th	Night	18% 13% 30% 27% 10% 1	760
	21st to end	Night	26% 14% 26% 26% 8%	836
November	1st to 10th	Night	18% 15% 30% 27% 10% 1	780
	11th to 20th	Night	23% 19% 28% 22% 7% 1	800
	21st to end	Night	23% 18% 28% 24% 7% 1	800
December	1st to 10th	Night	27% 18% 29% 20% 5%	800
	11th to 20th	Night	27% 19% 29% 22% 4	800
	21st to end	Night	27% 17% 31% 22% 2	880

Page generated at 2025-07-18 01:10:01. Version ac07

Copyright © 2025 Attilla Danko.