Chain O' Lakes State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chain O' Lakes State Park clear sky chart from 2005-11-06 to 2026-04-02.

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	14% 10% 4 9% 5% 5% 5% 4 5% 7% 33%	130938
	Night	14% 10% 4 9% 5% 4 4 4 5% 7% 33%	131114
Transparency	Day	49% 5% 11% 21% 12% 1	134507
	Night	49% 4 11% 21% 13% 1	135618
Seeing	Day	18% 10% 28% 23% 15% 6%	17519
	Night	19% 9% 29% 29% 13% 1	27483

By Month

Percentage Cloud Cover SE (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	14% 15% 9% 20% 7% 4 4 3 4 4 14%	4691
	11th to 20th	Day	11% 15% 8% 15% 7% 8% 6% 5% 5% 4 16%	4710
	21st to end	Day	18% 16% 8% 14% 7% 6% 6% 3 3 4 16%	5362
February	1st to 10th	Day	15% 15% 6% 12% 7% 6% 4 3 4 6% 22%	1993
	11th to 20th	Day	14% 14% 5% 13% 8% 5% 4 4 5% 5% 23%	2048
	21st to end	Day	15% 15% 6% 11% 5% 4 4 4 5% 6% 25%	1730
March	1st to 10th	Day	17% 13% 6% 11% 5% 4 3 3 4 5% 28%	4580
	11th to 20th	Day	12% 10% 4 7% 5% 4 5% 4 5% 7% 38%	4991
	21st to end	Day	18% 15% 5% 10% 6% 4 5% 4 5% 6% 22%	5718
April	1st to 10th	Day	17% 13% 4 8% 5% 4 4 3 5% 6% 30%	2412
	11th to 20th	Day	17% 9% 3 6% 5% 5% 4 3 5% 6% 36%	2418
	21st to end	Day	17% 9% 3 7% 5% 4 4 3 5% 7% 35%	2600
May	1st to 10th	Day	20% 9% 3 8% 5% 4 5% 3 5% 6% 31%	5862
	11th to 20th	Day	16% 7% 2 6% 5% 5% 5% 4 6% 8% 37%	5861
	21st to end	Day	15% 6% 2 6% 5% 5% 5% 4 6% 8% 38%	6653
June	1st to 10th	Day	10% 6% 2 7% 5% 5% 5% 5% 6% 8% 41%	2800
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 4 6% 9% 43%	2800
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 5% 7% 9% 40%	2800
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 6% 10% 41%	6360
	11th to 20th	Day	7% 5% 2 6% 4 5% 5% 5% 8% 11% 42%	6360
	21st to end	Day	9% 6% 2 7% 5% 5% 5% 4 7% 10% 39%	6754
August	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 4 6% 8% 45%	4234
	11th to 20th	Day	9% 5% 2 6% 4 5% 4 4 6% 8% 45%	4174
	21st to end	Day	7% 5% 2 6% 4 4 4 4 7% 9% 48%	4322
September	1st to 10th	Day	10% 5% 2 6% 5% 4 5% 4 6% 6% 46%	2340
	11th to 20th	Day	9% 4 1 5% 4 4 4 5% 7% 8% 49%	2200
	21st to end	Day	13% 7% 2 6% 4 5% 4 4 5% 9% 42%	2200
October	1st to 10th	Day	13% 6% 2 6% 4 4 4 4 5% 7% 45%	2200
	11th to 20th	Day	16% 7% 2 7% 4 4 5% 4 5% 7% 38%	2003
	21st to end	Day	18% 10% 4 8% 5% 5% 4 4 6% 7% 29%	1980
November	1st to 10th	Day	11% 9% 3 7% 4 4 3 4 5% 7% 44%	1852
	11th to 20th	Day	17% 14% 4 9% 5% 4 4 3 4 6% 30%	1890
	21st to end	Day	20% 14% 6% 9% 5% 3 4 3 5% 5% 26%	1890
December	1st to 10th	Day	10% 16% 5% 13% 5% 4 4 3 6% 6% 26%	2992
	11th to 20th	Day	17% 16% 9% 12% 6% 4 4 3 4 5% 21%	3088
	21st to end	Day	28% 19% 7% 13% 5% 4 4 3 3 4 12%	4070
January	1st to 10th	Night	13% 15% 7% 17% 6% 5% 4 3 4 5% 19%	8232
	11th to 20th	Night	10% 15% 8% 16% 8% 6% 5% 4 5% 5% 17%	8280
	21st to end	Night	17% 13% 6% 10% 6% 6% 6% 4 5% 6% 22%	8838
February	1st to 10th	Night	17% 14% 5% 10% 6% 5% 4 3 4 6% 25%	2625
	11th to 20th	Night	13% 13% 5% 10% 6% 5% 4 3 5% 6% 29%	2458
	21st to end	Night	18% 13% 4 11% 5% 4 4 3 4 5% 29%	2076
March	1st to 10th	Night	16% 11% 4 7% 5% 4 4 3 4 6% 35%	5493
	11th to 20th	Night	12% 7% 3 7% 4 5% 5% 4 5% 8% 42%	5187
	21st to end	Night	18% 10% 4 8% 5% 4 4 4 5% 7% 34%	5497
April	1st to 10th	Night	16% 11% 2 5% 5% 4 5% 4 5% 7% 36%	2010
	11th to 20th	Night	17% 8% 3 6% 5% 5% 5% 3 5% 6% 37%	1930
	21st to end	Night	16% 9% 3 6% 5% 4 5% 4 5% 6% 37%	1800
May	1st to 10th	Night	19% 11% 3 9% 5% 4 4 4 5% 6% 30%	4033
	11th to 20th	Night	18% 7% 2 6% 4 4 4 3 5% 7% 40%	4032
	21st to end	Night	16% 7% 2 6% 4 3 4 4 5% 8% 42%	4207
June	1st to 10th	Night	10% 5% 2 5% 3 4 4 3 6% 9% 48%	1600
	11th to 20th	Night	8% 5% 3 7% 6% 4 5% 3 7% 8% 45%	1600
	21st to end	Night	9% 5% 2 6% 5% 5% 4 4 7% 8% 45%	1600
July	1st to 10th	Night	8% 4 2 6% 5% 5% 4 4 6% 9% 47%	3618
	11th to 20th	Night	7% 5% 2 6% 4 4 5% 4 6% 10% 48%	3617
	21st to end	Night	10% 6% 2 6% 4 3 4 3 6% 9% 45%	4111
August	1st to 10th	Night	10% 6% 2 6% 4 4 5% 4 6% 10% 43%	2915
	11th to 20th	Night	8% 6% 2 7% 4 4 4 4 5% 7% 48%	2875
	21st to end	Night	8% 5% 2 5% 4 4 4 4 6% 8% 50%	3573
September	1st to 10th	Night	10% 5% 1 6% 3 4 4 3 4 7% 53%	2038
	11th to 20th	Night	10% 4 2 4 3 3 3 3 5% 7% 57%	2200
	21st to end	Night	13% 7% 3 5% 3 3 4 3 5% 7% 46%	2200
October	1st to 10th	Night	11% 6% 2 5% 4 4 4 3 5% 6% 51%	2200
	11th to 20th	Night	17% 8% 2 7% 5% 3 4 3 5% 5% 40%	2390
	21st to end	Night	20% 8% 2 6% 4 4 3 3 5% 7% 38%	2860
November	1st to 10th	Night	12% 9% 3 6% 4 4 3 3 5% 7% 43%	2666
	11th to 20th	Night	15% 12% 3 7% 5% 4 5% 3 7% 7% 32%	2730
	21st to end	Night	19% 14% 5% 9% 5% 4 4 4 5% 6% 26%	2730
December	1st to 10th	Night	12% 13% 5% 11% 6% 5% 4 4 6% 8% 26%	4404
	11th to 20th	Night	18% 16% 9% 13% 5% 4 4 3 5% 5% 20%	5339
	21st to end	Night	27% 18% 7% 12% 5% 4 4 3 4 5% 12%	7150

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	74% 3 10% 10% 3	4692
	11th to 20th	Day	69% 3 7% 9% 10% 1	4710
	21st to end	Day	74% 2 7% 12% 5%	5362
February	1st to 10th	Day	64% 5% 11% 13% 7% 1	1993
	11th to 20th	Day	62% 5% 8% 16% 7% 1	2058
	21st to end	Day	59% 5% 12% 16% 7% 1	1730
March	1st to 10th	Day	60% 3 7% 21% 9%	4580
	11th to 20th	Day	44% 4 13% 30% 8% 1	4991
	21st to end	Day	63% 5% 11% 15% 5% 1	5720
April	1st to 10th	Day	55% 6% 10% 18% 11%	2412
	11th to 20th	Day	49% 6% 10% 21% 12% 2	2418
	21st to end	Day	48% 5% 13% 19% 12% 2	2600
May	1st to 10th	Day	52% 7% 10% 17% 13%	5897
	11th to 20th	Day	44% 6% 14% 23% 12% 1	5865
	21st to end	Day	41% 6% 10% 24% 17% 1	6667
June	1st to 10th	Day	39% 7% 11% 24% 17% 2	2800
	11th to 20th	Day	37% 7% 11% 26% 17% 3	2800
	21st to end	Day	37% 9% 15% 20% 16% 3	2800
July	1st to 10th	Day	39% 3 10% 29% 16% 2	6291
	11th to 20th	Day	36% 3 15% 29% 15% 1	6285
	21st to end	Day	41% 4 13% 23% 18% 2	6560
August	1st to 10th	Day	36% 6% 15% 27% 16% 1	4221
	11th to 20th	Day	36% 5% 13% 28% 17% 1	4213
	21st to end	Day	32% 4 13% 31% 17% 3	4321
September	1st to 10th	Day	36% 6% 14% 21% 18% 3	2340
	11th to 20th	Day	31% 6% 12% 28% 21% 1	2200
	21st to end	Day	39% 6% 11% 24% 19% 1	2200
October	1st to 10th	Day	29% 4 10% 36% 21% 1	3590
	11th to 20th	Day	38% 3 12% 22% 24% 1	3232
	21st to end	Day	45% 4 11% 27% 13% 2	3180
November	1st to 10th	Day	40% 5% 12% 27% 16% 1	1852
	11th to 20th	Day	55% 5% 10% 19% 10% 1	1890
	21st to end	Day	60% 5% 10% 18% 6% 1	1890
December	1st to 10th	Day	58% 3 16% 19% 4	2992
	11th to 20th	Day	66% 5% 10% 15% 4	3085
	21st to end	Day	78% 3 7% 8% 4	4070
January	1st to 10th	Night	68% 3 8% 15% 5%	8233
	11th to 20th	Night	68% 3 8% 11% 10%	8280
	21st to end	Night	63% 2 12% 15% 7%	8838
February	1st to 10th	Night	61% 5% 11% 14% 8% 1	2625
	11th to 20th	Night	56% 5% 10% 20% 9% 1	2459
	21st to end	Night	57% 4 12% 17% 9% 2	2076
March	1st to 10th	Night	51% 3 9% 26% 9% 1	5493
	11th to 20th	Night	39% 5% 13% 29% 12% 2	5187
	21st to end	Night	50% 5% 12% 21% 12% 1	5497
April	1st to 10th	Night	46% 6% 11% 21% 15% 1	2010
	11th to 20th	Night	46% 6% 10% 18% 17% 2	1930
	21st to end	Night	46% 6% 11% 20% 14% 3	1800
May	1st to 10th	Night	54% 6% 9% 16% 13% 2	4060
	11th to 20th	Night	44% 6% 11% 25% 14% 1	4033
	21st to end	Night	40% 6% 12% 22% 18% 2	4215
June	1st to 10th	Night	32% 6% 12% 28% 19% 3	1600
	11th to 20th	Night	36% 7% 12% 24% 19% 3	1600
	21st to end	Night	35% 8% 17% 22% 16% 3	1600
July	1st to 10th	Night	35% 4 11% 27% 19% 5%	3580
	11th to 20th	Night	32% 4 18% 24% 20% 2	3572
	21st to end	Night	36% 4 16% 22% 19% 3	3992
August	1st to 10th	Night	36% 6% 14% 29% 13% 2	2904
	11th to 20th	Night	36% 5% 12% 30% 16% 1	2902
	21st to end	Night	33% 5% 12% 29% 20% 3	3573
September	1st to 10th	Night	31% 7% 13% 24% 21% 5%	2038
	11th to 20th	Night	27% 6% 8% 31% 25% 2	2200
	21st to end	Night	37% 5% 11% 27% 19% 2	2200
October	1st to 10th	Night	23% 3 7% 33% 33% 1	3590
	11th to 20th	Night	38% 3 9% 23% 26% 1	3900
	21st to end	Night	37% 3 9% 31% 19% 1	4610
November	1st to 10th	Night	40% 4 12% 26% 17% 1	2666
	11th to 20th	Night	50% 5% 12% 21% 10% 2	2730
	21st to end	Night	58% 4 12% 19% 7%	2730
December	1st to 10th	Night	55% 4 12% 23% 5% 1	4404
	11th to 20th	Night	67% 4 11% 10% 7% 1	5341
	21st to end	Night	76% 4 8% 8% 3	7150

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	22% 17% 37% 18% 5% 1	330
	11th to 20th	Day	23% 20% 41% 12% 3 1	330
	21st to end	Day	28% 18% 33% 18% 4	363
February	1st to 10th	Day	24% 18% 36% 18% 4 1	330
	11th to 20th	Day	25% 20% 34% 16% 5%	330
	21st to end	Day	22% 25% 40% 11% 3	273
March	1st to 10th	Day	24% 19% 38% 15% 3	330
	11th to 20th	Day	26% 14% 32% 20% 6% 1	493
	21st to end	Day	28% 15% 32% 18% 5% 1	594
April	1st to 10th	Day	22% 17% 31% 20% 9% 1	504
	11th to 20th	Day	21% 17% 32% 19% 9% 3	492
	21st to end	Day	22% 15% 31% 18% 11% 2	500
May	1st to 10th	Day	23% 12% 31% 22% 10% 3	503
	11th to 20th	Day	22% 8% 27% 23% 14% 6%	527
	21st to end	Day	13% 6% 27% 28% 16% 9%	663
June	1st to 10th	Day	12% 10% 28% 30% 16% 5%	730
	11th to 20th	Day	13% 5% 30% 26% 19% 6%	730
	21st to end	Day	13% 5% 29% 29% 18% 6%	730
July	1st to 10th	Day	11% 3 19% 30% 23% 14%	721
	11th to 20th	Day	10% 3 24% 30% 23% 11%	718
	21st to end	Day	9% 2 20% 31% 25% 12%	724
August	1st to 10th	Day	8% 3 15% 29% 29% 16%	526
	11th to 20th	Day	13% 3 16% 29% 29% 11%	519
	21st to end	Day	11% 2 13% 27% 31% 16%	583
September	1st to 10th	Day	13% 5% 19% 24% 26% 13%	530
	11th to 20th	Day	8% 3 14% 25% 32% 18%	530
	21st to end	Day	19% 8% 18% 24% 23% 8%	530
October	1st to 10th	Day	14% 5% 24% 30% 19% 8%	530
	11th to 20th	Day	18% 13% 28% 30% 11% 1	480
	21st to end	Day	25% 16% 36% 18% 4 1	363
November	1st to 10th	Day	16% 15% 32% 25% 10% 3	330
	11th to 20th	Day	27% 18% 31% 16% 8%	330
	21st to end	Day	30% 15% 37% 15% 3	330
December	1st to 10th	Day	23% 18% 35% 16% 7%	330
	11th to 20th	Day	23% 22% 36% 15% 4	330
	21st to end	Day	29% 18% 37% 13% 2	363
January	1st to 10th	Night	21% 15% 36% 23% 5%	1050
	11th to 20th	Night	23% 13% 39% 19% 4 1	1050
	21st to end	Night	22% 15% 37% 23% 3	1078
February	1st to 10th	Night	24% 12% 37% 24% 3	840
	11th to 20th	Night	20% 15% 38% 24% 3	823
	21st to end	Night	25% 14% 38% 20% 2	692
March	1st to 10th	Night	20% 13% 37% 24% 6% 1	840
	11th to 20th	Night	18% 13% 37% 26% 5% 1	840
	21st to end	Night	25% 9% 32% 27% 5%	884
April	1st to 10th	Night	20% 13% 33% 27% 7%	603
	11th to 20th	Night	20% 10% 34% 28% 7% 1	593
	21st to end	Night	20% 6% 36% 28% 9% 1	600
May	1st to 10th	Night	22% 6% 32% 33% 8%	600
	11th to 20th	Night	20% 5% 27% 34% 14% 1	591
	21st to end	Night	14% 4 25% 38% 18% 2	650
June	1st to 10th	Night	13% 2 27% 42% 16% 1	600
	11th to 20th	Night	11% 4 25% 41% 19% 1	600
	21st to end	Night	9% 3 25% 36% 25% 2	600
July	1st to 10th	Night	9% 3 15% 43% 28% 3	585
	11th to 20th	Night	9% 3 16% 40% 29% 3	582
	21st to end	Night	7% 2 15% 43% 32% 1	657
August	1st to 10th	Night	7% 2 14% 42% 31% 5%	597
	11th to 20th	Night	9% 2 14% 42% 29% 4	594
	21st to end	Night	10% 1 15% 34% 36% 4	660
September	1st to 10th	Night	10% 4 17% 35% 32% 3	638
	11th to 20th	Night	11% 4 12% 37% 33% 3	800
	21st to end	Night	17% 5% 22% 33% 20% 4	800
October	1st to 10th	Night	15% 5% 23% 35% 20% 3	800
	11th to 20th	Night	21% 11% 28% 29% 11% 1	800
	21st to end	Night	24% 12% 31% 26% 7%	880
November	1st to 10th	Night	15% 12% 35% 27% 10% 1	820
	11th to 20th	Night	22% 14% 33% 24% 6% 1	840
	21st to end	Night	25% 13% 31% 25% 5%	840
December	1st to 10th	Night	26% 13% 34% 22% 5%	851
	11th to 20th	Night	25% 14% 35% 22% 4	1050
	21st to end	Night	30% 14% 32% 21% 3	1155

Page generated at 2026-03-30 02:18:40. Version ac07

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