Manitoulin Eco Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Manitoulin Eco Park clear sky chart from 2005-11-06 to 2025-09-04.

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 8% 5% 4 4 3 5% 7% 36%	126105
	Night	14% 12% 4 9% 5% 5% 4 4 5% 6% 32%	122727
Transparency	Day	47% 6% 12% 22% 11% 1	129604
	Night	51% 6% 12% 19% 11% 1	127315
Seeing	Day	19% 15% 33% 23% 9% 2	16428
	Night	20% 14% 31% 25% 10% 1	25609

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	14% 17% 8% 11% 4 3 4 3 3 5% 28%	3181
	11th to 20th	Day	9% 16% 7% 19% 11% 7% 5% 3 4 4 15%	3589
	21st to end	Day	12% 19% 9% 16% 7% 5% 4 3 4 5% 16%	4229
February	1st to 10th	Day	10% 17% 6% 13% 8% 4 4 4 4 6% 24%	1800
	11th to 20th	Day	10% 15% 5% 11% 6% 5% 5% 4 5% 5% 28%	1753
	21st to end	Day	11% 17% 5% 13% 6% 4 5% 3 4 5% 26%	1635
March	1st to 10th	Day	15% 12% 3 8% 4 4 4 3 5% 5% 35%	4679
	11th to 20th	Day	10% 13% 5% 11% 6% 5% 5% 4 6% 7% 29%	4980
	21st to end	Day	16% 13% 6% 7% 5% 4 3 3 5% 5% 33%	5465
April	1st to 10th	Day	16% 14% 4 6% 5% 4 4 3 5% 6% 33%	2349
	11th to 20th	Day	18% 9% 3 6% 4 4 4 3 5% 6% 38%	2572
	21st to end	Day	20% 9% 3 6% 3 3 4 3 5% 8% 36%	2600
May	1st to 10th	Day	17% 7% 2 5% 4 4 4 3 5% 7% 42%	5888
	11th to 20th	Day	13% 7% 3 6% 4 4 4 3 4 6% 44%	6102
	21st to end	Day	16% 8% 3 6% 4 4 4 3 5% 6% 41%	7176
June	1st to 10th	Day	13% 6% 2 6% 4 5% 5% 4 6% 6% 41%	3000
	11th to 20th	Day	11% 7% 2 5% 4 4 5% 4 6% 9% 43%	3000
	21st to end	Day	15% 7% 3 6% 4 4 4 4 6% 8% 39%	3000
July	1st to 10th	Day	13% 7% 3 7% 4 4 4 3 5% 8% 41%	6819
	11th to 20th	Day	9% 5% 2 5% 3 4 4 3 5% 7% 53%	6692
	21st to end	Day	8% 5% 2 5% 3 3 4 3 6% 8% 53%	6703
August	1st to 10th	Day	9% 5% 2 6% 4 5% 5% 4 7% 10% 43%	4234
	11th to 20th	Day	15% 5% 2 6% 4 4 4 3 5% 8% 44%	4174
	21st to end	Day	9% 6% 2 5% 4 4 5% 4 5% 8% 47%	4675
September	1st to 10th	Day	10% 7% 3 7% 5% 4 4 4 6% 9% 42%	2284
	11th to 20th	Day	12% 5% 3 4 4 4 4 4 5% 9% 47%	2090
	21st to end	Day	16% 8% 2 6% 5% 4 4 3 5% 7% 39%	2090
October	1st to 10th	Day	17% 8% 3 7% 5% 4 4 4 5% 6% 37%	1953
	11th to 20th	Day	23% 11% 3 8% 5% 5% 5% 4 5% 6% 26%	1900
	21st to end	Day	25% 13% 4 9% 4 4 4 3 5% 7% 22%	1945
November	1st to 10th	Day	15% 14% 4 10% 5% 5% 4 4 5% 6% 28%	1732
	11th to 20th	Day	17% 15% 5% 10% 6% 5% 4 4 5% 7% 22%	1600
	21st to end	Day	21% 21% 5% 11% 6% 5% 5% 3 5% 5% 14%	1600
December	1st to 10th	Day	14% 22% 8% 11% 6% 6% 5% 4 5% 6% 15%	2519
	11th to 20th	Day	18% 18% 6% 13% 6% 5% 4 3 5% 5% 18%	2621
	21st to end	Day	25% 25% 7% 9% 5% 4 3 3 4 4 10%	3476
January	1st to 10th	Night	10% 15% 7% 12% 5% 6% 5% 4 5% 6% 25%	6783
	11th to 20th	Night	10% 16% 6% 16% 7% 5% 4 4 5% 6% 20%	6316
	21st to end	Night	10% 17% 8% 15% 6% 6% 5% 4 5% 5% 20%	6723
February	1st to 10th	Night	10% 15% 6% 12% 7% 5% 5% 4 6% 5% 26%	2600
	11th to 20th	Night	10% 14% 4 12% 7% 5% 5% 3 6% 6% 28%	2533
	21st to end	Night	12% 16% 5% 10% 5% 5% 4 3 6% 7% 26%	1994
March	1st to 10th	Night	15% 9% 3 9% 5% 4 4 4 4 6% 38%	5147
	11th to 20th	Night	11% 10% 4 9% 5% 6% 5% 4 6% 8% 34%	4979
	21st to end	Night	18% 11% 5% 9% 5% 4 3 2 4 5% 35%	5467
April	1st to 10th	Night	18% 10% 3 7% 5% 4 4 3 6% 5% 35%	2069
	11th to 20th	Night	17% 9% 2 6% 4 4 4 3 5% 7% 38%	1777
	21st to end	Night	16% 11% 4 9% 5% 4 4 4 5% 5% 33%	1800
May	1st to 10th	Night	15% 7% 3 7% 5% 5% 4 4 5% 7% 38%	4053
	11th to 20th	Night	10% 8% 3 8% 4 4 5% 3 6% 7% 42%	3787
	21st to end	Night	17% 9% 3 7% 4 4 4 3 5% 6% 38%	3693
June	1st to 10th	Night	11% 7% 2 6% 4 4 5% 5% 7% 8% 40%	1400
	11th to 20th	Night	11% 6% 2 4 5% 4 5% 5% 6% 9% 43%	1400
	21st to end	Night	12% 7% 3 6% 5% 5% 5% 3 7% 7% 41%	1400
July	1st to 10th	Night	12% 6% 2 6% 4 4 4 4 6% 9% 43%	3160
	11th to 20th	Night	10% 5% 2 5% 3 4 4 3 5% 8% 52%	3285
	21st to end	Night	8% 6% 2 6% 4 4 4 4 5% 8% 50%	4161
August	1st to 10th	Night	8% 5% 2 6% 5% 4 4 4 6% 8% 46%	2915
	11th to 20th	Night	13% 4 2 5% 4 5% 4 4 5% 8% 46%	2875
	21st to end	Night	8% 6% 3 6% 4 4 4 3 5% 7% 50%	3223
September	1st to 10th	Night	11% 6% 3 6% 4 3 3 3 5% 8% 48%	1939
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 6% 7% 51%	2090
	21st to end	Night	17% 7% 2 6% 4 4 4 3 5% 7% 41%	2090
October	1st to 10th	Night	17% 7% 3 8% 4 4 4 3 4 6% 38%	2225
	11th to 20th	Night	21% 10% 3 8% 5% 4 5% 4 6% 6% 28%	2280
	21st to end	Night	23% 12% 3 8% 6% 4 4 4 5% 6% 25%	2650
November	1st to 10th	Night	17% 11% 3 8% 5% 4 4 4 5% 7% 31%	2565
	11th to 20th	Night	15% 16% 5% 10% 6% 5% 4 4 5% 6% 22%	2800
	21st to end	Night	20% 16% 5% 11% 6% 5% 5% 3 5% 6% 19%	2800
December	1st to 10th	Night	15% 17% 5% 12% 6% 5% 5% 4 5% 6% 19%	4660
	11th to 20th	Night	14% 18% 6% 14% 6% 5% 5% 4 4 5% 18%	5586
	21st to end	Night	22% 22% 7% 11% 5% 4 4 3 4 4 13%	7502

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	59% 6% 9% 17% 6% 3	3182
	11th to 20th	Day	73% 5% 7% 9% 5% 1	3620
	21st to end	Day	69% 7% 7% 10% 7%	4229
February	1st to 10th	Day	61% 6% 12% 15% 5% 1	1800
	11th to 20th	Day	57% 6% 11% 15% 10% 1	1762
	21st to end	Day	60% 6% 9% 18% 7%	1635
March	1st to 10th	Day	49% 6% 13% 11% 16% 5%	4682
	11th to 20th	Day	53% 6% 14% 17% 9% 1	4980
	21st to end	Day	50% 6% 15% 15% 12% 3	5465
April	1st to 10th	Day	51% 5% 13% 18% 12% 1	2349
	11th to 20th	Day	46% 5% 8% 25% 15% 1	2572
	21st to end	Day	46% 6% 11% 20% 14% 3	2600
May	1st to 10th	Day	40% 5% 12% 22% 16% 4	5897
	11th to 20th	Day	40% 7% 10% 20% 21% 2	6106
	21st to end	Day	43% 6% 11% 19% 16% 4	7176
June	1st to 10th	Day	39% 8% 12% 26% 14% 2	3000
	11th to 20th	Day	37% 6% 14% 25% 17% 2	3000
	21st to end	Day	41% 7% 13% 23% 13% 2	3000
July	1st to 10th	Day	41% 5% 14% 27% 12% 1	6746
	11th to 20th	Day	31% 5% 14% 39% 11%	6611
	21st to end	Day	29% 5% 13% 36% 16% 1	6511
August	1st to 10th	Day	34% 7% 14% 30% 13% 1	4221
	11th to 20th	Day	38% 6% 17% 28% 11%	4213
	21st to end	Day	34% 6% 15% 34% 10% 1	4674
September	1st to 10th	Day	38% 8% 16% 28% 10% 1	2284
	11th to 20th	Day	35% 6% 17% 30% 11% 1	2090
	21st to end	Day	44% 8% 15% 23% 9%	2090
October	1st to 10th	Day	37% 6% 11% 27% 18%	3239
	11th to 20th	Day	47% 6% 14% 25% 8%	3140
	21st to end	Day	58% 6% 13% 16% 7%	3182
November	1st to 10th	Day	56% 7% 14% 18% 5%	1732
	11th to 20th	Day	61% 8% 12% 14% 5%	1600
	21st to end	Day	72% 7% 10% 9% 3	1600
December	1st to 10th	Day	70% 6% 14% 8% 2	2519
	11th to 20th	Day	67% 6% 11% 11% 5%	2621
	21st to end	Day	75% 8% 6% 8% 4	3476
January	1st to 10th	Night	57% 8% 10% 16% 7% 1	6783
	11th to 20th	Night	64% 7% 10% 11% 8%	6360
	21st to end	Night	66% 6% 8% 11% 8% 1	6723
February	1st to 10th	Night	60% 6% 11% 16% 6% 1	2600
	11th to 20th	Night	55% 7% 11% 17% 9% 1	2535
	21st to end	Night	56% 6% 12% 17% 8%	1994
March	1st to 10th	Night	46% 5% 14% 16% 16% 4	5157
	11th to 20th	Night	47% 6% 16% 20% 9% 1	4980
	21st to end	Night	52% 5% 9% 17% 15% 2	5467
April	1st to 10th	Night	50% 5% 9% 21% 14% 1	2069
	11th to 20th	Night	44% 5% 9% 22% 18% 2	1777
	21st to end	Night	51% 6% 8% 17% 15% 3	1800
May	1st to 10th	Night	45% 6% 9% 21% 15% 4	4060
	11th to 20th	Night	40% 6% 10% 24% 18% 2	3788
	21st to end	Night	46% 6% 10% 20% 14% 5%	3694
June	1st to 10th	Night	39% 7% 12% 22% 17% 3	1400
	11th to 20th	Night	35% 7% 13% 23% 20% 2	1400
	21st to end	Night	40% 7% 15% 23% 14% 2	1400
July	1st to 10th	Night	37% 5% 14% 27% 14% 3	3125
	11th to 20th	Night	30% 5% 11% 37% 15% 1	3243
	21st to end	Night	32% 5% 11% 31% 20%	4039
August	1st to 10th	Night	35% 6% 14% 30% 14% 1	2904
	11th to 20th	Night	36% 7% 17% 26% 12% 1	2902
	21st to end	Night	33% 6% 14% 33% 13% 1	3223
September	1st to 10th	Night	34% 7% 14% 30% 13% 2	1939
	11th to 20th	Night	32% 6% 17% 34% 11% 1	2090
	21st to end	Night	44% 7% 15% 24% 11%	2090
October	1st to 10th	Night	36% 5% 9% 32% 17%	3719
	11th to 20th	Night	44% 6% 15% 26% 9%	3779
	21st to end	Night	51% 7% 18% 17% 6%	4363
November	1st to 10th	Night	52% 8% 12% 21% 6%	2565
	11th to 20th	Night	61% 8% 14% 11% 5%	2800
	21st to end	Night	66% 8% 12% 12% 3	2800
December	1st to 10th	Night	64% 8% 15% 10% 3	4660
	11th to 20th	Night	67% 7% 10% 9% 7% 1	5585
	21st to end	Night	72% 8% 8% 7% 5%	7502

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	23% 21% 35% 16% 6%	205
	11th to 20th	Day	19% 21% 38% 17% 5%	300
	21st to end	Day	25% 15% 35% 18% 6% 1	330
February	1st to 10th	Day	25% 25% 33% 13% 4	300
	11th to 20th	Day	22% 23% 38% 14% 2	300
	21st to end	Day	25% 29% 36% 10% 1	249
March	1st to 10th	Day	22% 22% 36% 16% 3 1	385
	11th to 20th	Day	20% 18% 36% 20% 5% 1	500
	21st to end	Day	26% 18% 31% 20% 5% 1	550
April	1st to 10th	Day	24% 14% 32% 22% 7% 1	500
	11th to 20th	Day	27% 21% 25% 14% 10% 3	492
	21st to end	Day	28% 13% 35% 17% 7% 1	500
May	1st to 10th	Day	20% 13% 38% 20% 7% 2	503
	11th to 20th	Day	17% 13% 32% 25% 11% 2	527
	21st to end	Day	15% 9% 36% 26% 13% 2	670
June	1st to 10th	Day	15% 13% 35% 28% 9%	730
	11th to 20th	Day	13% 12% 37% 28% 8% 2	730
	21st to end	Day	19% 12% 33% 25% 9% 2	730
July	1st to 10th	Day	10% 8% 35% 34% 12% 2	721
	11th to 20th	Day	10% 9% 33% 33% 11% 4	718
	21st to end	Day	11% 6% 36% 30% 12% 4	699
August	1st to 10th	Day	12% 7% 28% 32% 16% 5%	526
	11th to 20th	Day	12% 6% 27% 31% 16% 9%	519
	21st to end	Day	13% 10% 30% 28% 14% 6%	583
September	1st to 10th	Day	14% 11% 28% 27% 14% 7%	502
	11th to 20th	Day	12% 9% 26% 30% 15% 7%	490
	21st to end	Day	18% 13% 27% 24% 14% 3	490
October	1st to 10th	Day	21% 18% 25% 24% 10% 2	490
	11th to 20th	Day	22% 22% 35% 14% 6% 1	490
	21st to end	Day	31% 21% 32% 13% 2 1	394
November	1st to 10th	Day	25% 24% 33% 15% 3	285
	11th to 20th	Day	27% 22% 36% 14% 2	200
	21st to end	Day	31% 27% 30% 9% 3	200
December	1st to 10th	Day	30% 20% 29% 17% 5%	200
	11th to 20th	Day	31% 25% 32% 11% 2	200
	21st to end	Day	31% 28% 29% 9% 2 1	220
January	1st to 10th	Night	20% 18% 34% 23% 5% 1	1000
	11th to 20th	Night	24% 19% 30% 22% 6% 1	1000
	21st to end	Night	19% 12% 35% 25% 8% 1	983
February	1st to 10th	Night	18% 19% 39% 20% 4	800
	11th to 20th	Night	18% 18% 34% 24% 6% 1	783
	21st to end	Night	20% 17% 39% 20% 4	660
March	1st to 10th	Night	17% 17% 38% 22% 6%	800
	11th to 20th	Night	17% 15% 39% 21% 8% 1	800
	21st to end	Night	19% 13% 32% 28% 7%	880
April	1st to 10th	Night	24% 13% 35% 24% 4	739
	11th to 20th	Night	22% 12% 31% 22% 10% 2	593
	21st to end	Night	21% 13% 31% 23% 11% 1	600
May	1st to 10th	Night	15% 7% 33% 32% 12% 2	600
	11th to 20th	Night	15% 7% 30% 35% 12%	489
	21st to end	Night	14% 6% 30% 33% 15% 1	433
June	1st to 10th	Night	15% 9% 34% 30% 12% 1	400
	11th to 20th	Night	13% 10% 26% 35% 16% 1	400
	21st to end	Night	15% 6% 25% 38% 15% 2	400
July	1st to 10th	Night	9% 6% 27% 42% 16% 1	390
	11th to 20th	Night	9% 3 26% 40% 20% 2	435
	21st to end	Night	10% 4 25% 37% 22% 1	657
August	1st to 10th	Night	9% 5% 25% 39% 20% 2	597
	11th to 20th	Night	11% 5% 22% 30% 28% 4	594
	21st to end	Night	12% 5% 24% 33% 22% 4	660
September	1st to 10th	Night	15% 9% 25% 27% 18% 7%	719
	11th to 20th	Night	11% 7% 26% 31% 18% 7%	760
	21st to end	Night	19% 8% 26% 27% 16% 4	760
October	1st to 10th	Night	20% 14% 26% 26% 12% 1	760
	11th to 20th	Night	26% 17% 29% 19% 8%	760
	21st to end	Night	30% 16% 30% 19% 4 1	836
November	1st to 10th	Night	24% 17% 31% 20% 8% 1	780
	11th to 20th	Night	24% 22% 28% 19% 7%	800
	21st to end	Night	28% 20% 31% 16% 5%	800
December	1st to 10th	Night	29% 22% 30% 13% 6%	841
	11th to 20th	Night	24% 22% 36% 14% 3 1	1000
	21st to end	Night	32% 17% 30% 16% 5%	1100

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