Lake Superior Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Superior Provincial Park clear sky chart from 2005-11-06 to 2026-09-29.

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	16% 11% 4 9% 5% 4 4 3 5% 7% 33%	149795
	Night	14% 14% 5% 11% 6% 4 4 3 5% 6% 28%	141912
Transparency	Day	50% 6% 13% 21% 9% 1	153241
	Night	56% 7% 12% 18% 8% 1	146555
Seeing	Day	21% 12% 29% 25% 10% 2	18171
	Night	22% 11% 29% 27% 10% 1	27430

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	7% 20% 11% 15% 11% 6% 5% 3 5% 5% 13%	4350
	11th to 20th	Day	7% 16% 7% 18% 7% 5% 5% 4 6% 6% 18%	4679
	21st to end	Day	4 16% 9% 17% 7% 7% 5% 4 5% 6% 18%	5156
February	1st to 10th	Day	8% 17% 5% 13% 11% 9% 6% 3 5% 6% 18%	1755
	11th to 20th	Day	9% 17% 7% 12% 10% 6% 5% 4 5% 5% 21%	1936
	21st to end	Day	8% 17% 8% 15% 6% 5% 4 4 5% 6% 21%	1730
March	1st to 10th	Day	14% 12% 3 11% 5% 4 4 4 5% 8% 29%	4578
	11th to 20th	Day	14% 17% 5% 9% 6% 5% 4 3 5% 6% 26%	5013
	21st to end	Day	18% 15% 7% 12% 5% 3 4 2 3 5% 26%	5720
April	1st to 10th	Day	17% 15% 5% 8% 4 3 4 3 5% 7% 29%	2520
	11th to 20th	Day	19% 13% 5% 8% 4 4 3 3 5% 6% 31%	2680
	21st to end	Day	16% 12% 4 7% 5% 4 4 4 6% 7% 32%	2730
May	1st to 10th	Day	14% 9% 3 7% 4 4 4 3 5% 7% 41%	7642
	11th to 20th	Day	19% 7% 3 6% 4 3 4 3 5% 6% 41%	8138
	21st to end	Day	14% 7% 3 7% 4 4 3 3 4 7% 44%	9716
June	1st to 10th	Day	18% 7% 2 6% 4 5% 5% 4 6% 8% 34%	3150
	11th to 20th	Day	16% 8% 3 6% 4 5% 5% 4 7% 9% 35%	3150
	21st to end	Day	19% 7% 2 6% 4 4 5% 4 5% 8% 36%	3150
July	1st to 10th	Day	15% 8% 2 6% 4 4 4 3 5% 7% 41%	8879
	11th to 20th	Day	16% 8% 2 6% 3 3 4 3 5% 8% 42%	8445
	21st to end	Day	17% 6% 2 5% 3 4 3 3 5% 8% 44%	8992
August	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 6% 9% 42%	6328
	11th to 20th	Day	15% 5% 2 5% 3 4 4 3 5% 8% 46%	5951
	21st to end	Day	23% 8% 3 7% 4 4 4 3 4 6% 35%	6575
September	1st to 10th	Day	22% 7% 2 6% 4 4 3 3 5% 7% 37%	2477
	11th to 20th	Day	21% 6% 2 4 4 4 4 4 6% 8% 40%	2310
	21st to end	Day	22% 8% 3 7% 4 3 4 2 5% 7% 36%	2288
October	1st to 10th	Day	22% 11% 3 7% 3 4 4 3 6% 5% 32%	2154
	11th to 20th	Day	25% 17% 4 9% 6% 4 3 3 5% 6% 18%	1881
	21st to end	Day	24% 19% 4 8% 6% 4 4 4 4 5% 20%	1980
November	1st to 10th	Day	21% 21% 4 9% 5% 3 4 4 5% 5% 20%	1852
	11th to 20th	Day	18% 19% 7% 11% 5% 4 4 4 4 6% 17%	1750
	21st to end	Day	18% 27% 7% 10% 6% 4 4 4 4 4 11%	1546
December	1st to 10th	Day	11% 25% 11% 16% 7% 5% 3 2 4 5% 12%	2350
	11th to 20th	Day	10% 20% 7% 16% 8% 5% 5% 4 5% 5% 14%	2691
	21st to end	Day	20% 22% 8% 13% 4 4 3 2 3 4 17%	3553
January	1st to 10th	Night	9% 17% 9% 15% 8% 6% 5% 3 5% 6% 17%	8573
	11th to 20th	Night	6% 21% 10% 17% 7% 4 4 4 5% 6% 15%	8236
	21st to end	Night	5% 13% 10% 18% 10% 6% 7% 4 6% 6% 15%	9058
February	1st to 10th	Night	8% 18% 7% 16% 13% 6% 5% 4 5% 4 15%	2863
	11th to 20th	Night	9% 14% 7% 16% 8% 6% 6% 4 6% 5% 19%	2568
	21st to end	Night	9% 18% 7% 12% 8% 7% 5% 3 5% 5% 21%	2076
March	1st to 10th	Night	15% 13% 4 10% 4 4 4 3 6% 8% 31%	5482
	11th to 20th	Night	15% 16% 5% 10% 5% 4 4 3 5% 6% 27%	5165
	21st to end	Night	18% 15% 7% 12% 5% 4 3 2 4 5% 26%	5496
April	1st to 10th	Night	18% 13% 4 8% 5% 4 4 4 5% 6% 30%	2100
	11th to 20th	Night	19% 13% 4 8% 5% 4 3 3 4 5% 33%	1888
	21st to end	Night	18% 11% 3 7% 4 3 3 3 4 7% 36%	1890
May	1st to 10th	Night	13% 8% 4 7% 4 4 3 3 5% 6% 43%	5257
	11th to 20th	Night	15% 8% 2 7% 4 4 4 3 5% 7% 40%	4731
	21st to end	Night	11% 8% 3 7% 4 5% 4 3 5% 5% 45%	4492
June	1st to 10th	Night	17% 7% 2 6% 5% 4 5% 3 5% 8% 39%	1470
	11th to 20th	Night	18% 9% 3 8% 3 3 3 4 5% 8% 36%	1470
	21st to end	Night	15% 7% 2 6% 5% 4 5% 4 6% 7% 39%	1470
July	1st to 10th	Night	15% 7% 2 7% 4 4 4 4 5% 9% 39%	4110
	11th to 20th	Night	15% 6% 2 6% 4 4 4 3 5% 8% 42%	4528
	21st to end	Night	16% 7% 3 7% 4 4 4 3 6% 7% 40%	5118
August	1st to 10th	Night	16% 8% 3 6% 5% 4 4 4 5% 6% 38%	3821
	11th to 20th	Night	12% 4 1 5% 3 4 4 3 6% 8% 49%	4095
	21st to end	Night	19% 8% 2 6% 4 3 3 3 5% 6% 41%	4548
September	1st to 10th	Night	17% 8% 3 6% 3 3 4 3 4 7% 42%	2121
	11th to 20th	Night	19% 6% 2 5% 4 4 3 4 5% 8% 41%	2310
	21st to end	Night	23% 7% 2 5% 3 2 3 3 4 7% 39%	2289
October	1st to 10th	Night	23% 10% 3 6% 4 4 4 3 6% 5% 33%	2245
	11th to 20th	Night	25% 15% 3 7% 5% 4 4 3 4 5% 24%	2515
	21st to end	Night	24% 18% 3 9% 5% 4 4 3 4 6% 21%	2860
November	1st to 10th	Night	22% 19% 5% 8% 4 4 4 3 4 5% 22%	2666
	11th to 20th	Night	20% 22% 6% 11% 5% 4 4 3 5% 5% 16%	2867
	21st to end	Night	18% 23% 8% 11% 5% 4 5% 3 5% 5% 14%	3071
December	1st to 10th	Night	12% 24% 8% 14% 6% 5% 5% 4 4 5% 15%	5060
	11th to 20th	Night	10% 22% 8% 19% 7% 4 4 3 4 4 16%	5736
	21st to end	Night	17% 22% 8% 14% 5% 4 4 2 4 5% 15%	7667

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	71% 7% 9% 9% 3 2	4351
	11th to 20th	Day	65% 6% 9% 12% 8%	4710
	21st to end	Day	64% 8% 8% 12% 7%	5156
February	1st to 10th	Day	66% 8% 10% 10% 5%	1755
	11th to 20th	Day	64% 7% 11% 10% 7% 1	1945
	21st to end	Day	62% 6% 10% 13% 9% 1	1730
March	1st to 10th	Day	52% 6% 14% 12% 13% 3	4580
	11th to 20th	Day	58% 5% 12% 15% 9% 1	5013
	21st to end	Day	63% 4 10% 12% 9% 2	5720
April	1st to 10th	Day	54% 6% 11% 18% 9% 1	2520
	11th to 20th	Day	53% 4 11% 20% 10% 1	2680
	21st to end	Day	48% 6% 11% 19% 13% 3	2730
May	1st to 10th	Day	41% 5% 9% 29% 14% 2	7651
	11th to 20th	Day	44% 6% 10% 23% 14% 4	8142
	21st to end	Day	39% 5% 11% 26% 15% 3	9717
June	1st to 10th	Day	46% 8% 12% 20% 12% 2	3150
	11th to 20th	Day	44% 8% 14% 22% 11% 1	3150
	21st to end	Day	45% 8% 14% 23% 10% 1	3150
July	1st to 10th	Day	41% 6% 15% 27% 10% 1	8806
	11th to 20th	Day	40% 5% 20% 28% 7% 1	8367
	21st to end	Day	39% 6% 17% 32% 6%	8794
August	1st to 10th	Day	36% 7% 19% 27% 9% 2	6313
	11th to 20th	Day	36% 5% 20% 33% 6%	5990
	21st to end	Day	50% 6% 14% 21% 8%	6574
September	1st to 10th	Day	46% 5% 16% 22% 10%	2477
	11th to 20th	Day	42% 7% 20% 27% 5%	2310
	21st to end	Day	48% 6% 16% 21% 8% 1	2288
October	1st to 10th	Day	43% 6% 17% 23% 11%	3505
	11th to 20th	Day	57% 6% 15% 18% 4	3045
	21st to end	Day	67% 5% 11% 12% 5%	3180
November	1st to 10th	Day	66% 6% 11% 13% 4	1852
	11th to 20th	Day	68% 9% 11% 9% 3	1750
	21st to end	Day	77% 8% 7% 6% 2	1546
December	1st to 10th	Day	76% 6% 10% 7% 2	2350
	11th to 20th	Day	71% 7% 10% 9% 3	2691
	21st to end	Day	72% 6% 7% 10% 4	3553
January	1st to 10th	Night	67% 8% 9% 10% 4 2	8573
	11th to 20th	Night	70% 6% 8% 10% 7%	8280
	21st to end	Night	66% 9% 8% 11% 5% 1	9058
February	1st to 10th	Night	71% 7% 9% 9% 4	2863
	11th to 20th	Night	64% 8% 12% 11% 4	2570
	21st to end	Night	62% 7% 11% 13% 7%	2076
March	1st to 10th	Night	51% 6% 14% 14% 13% 2	5493
	11th to 20th	Night	56% 5% 16% 16% 7% 1	5166
	21st to end	Night	59% 7% 9% 14% 10% 1	5496
April	1st to 10th	Night	54% 6% 10% 18% 11% 1	2100
	11th to 20th	Night	53% 4 10% 21% 11% 2	1888
	21st to end	Night	48% 4 12% 18% 14% 3	1890
May	1st to 10th	Night	41% 5% 9% 25% 17% 3	5264
	11th to 20th	Night	43% 6% 11% 29% 9% 3	4732
	21st to end	Night	40% 5% 10% 23% 16% 5%	4493
June	1st to 10th	Night	42% 7% 12% 20% 18% 1	1470
	11th to 20th	Night	45% 8% 11% 20% 13% 2	1470
	21st to end	Night	42% 9% 14% 24% 10% 1	1470
July	1st to 10th	Night	40% 7% 13% 28% 11% 1	4075
	11th to 20th	Night	39% 5% 17% 31% 7%	4484
	21st to end	Night	42% 6% 14% 28% 10%	5002
August	1st to 10th	Night	45% 6% 14% 25% 11%	3812
	11th to 20th	Night	32% 6% 23% 32% 7%	4122
	21st to end	Night	43% 5% 12% 28% 10%	4548
September	1st to 10th	Night	43% 6% 14% 27% 10% 1	2121
	11th to 20th	Night	41% 9% 16% 27% 6%	2310
	21st to end	Night	45% 6% 16% 22% 9% 1	2289
October	1st to 10th	Night	42% 6% 14% 28% 10%	3674
	11th to 20th	Night	50% 6% 15% 25% 4	4090
	21st to end	Night	66% 7% 14% 9% 3	4610
November	1st to 10th	Night	65% 6% 10% 14% 5%	2666
	11th to 20th	Night	70% 8% 9% 9% 3	2867
	21st to end	Night	72% 9% 12% 6% 1	3071
December	1st to 10th	Night	72% 7% 12% 7% 2	5060
	11th to 20th	Night	73% 6% 8% 9% 4 1	5735
	21st to end	Night	71% 8% 7% 10% 4	7667

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	20% 18% 35% 18% 8% 1	267
	11th to 20th	Day	17% 15% 35% 24% 7% 1	330
	21st to end	Day	15% 12% 39% 27% 7%	363
February	1st to 10th	Day	21% 21% 33% 20% 5% 1	330
	11th to 20th	Day	19% 19% 39% 17% 5% 2	330
	21st to end	Day	20% 25% 39% 14% 2	273
March	1st to 10th	Day	20% 18% 40% 18% 4	330
	11th to 20th	Day	22% 17% 33% 21% 5% 1	502
	21st to end	Day	24% 19% 30% 20% 6% 1	594
April	1st to 10th	Day	23% 13% 34% 24% 5% 1	540
	11th to 20th	Day	25% 13% 31% 19% 9% 2	532
	21st to end	Day	22% 11% 33% 22% 9% 2	540
May	1st to 10th	Day	20% 12% 31% 25% 10% 3	543
	11th to 20th	Day	21% 10% 32% 26% 9% 3	733
	21st to end	Day	19% 9% 31% 29% 10% 2	844
June	1st to 10th	Day	20% 8% 32% 29% 10% 1	780
	11th to 20th	Day	20% 9% 29% 29% 11% 2	780
	21st to end	Day	21% 7% 27% 29% 14% 3	780
July	1st to 10th	Day	15% 6% 27% 36% 13% 2	771
	11th to 20th	Day	16% 8% 25% 33% 15% 3	768
	21st to end	Day	19% 4 25% 34% 14% 3	849
August	1st to 10th	Day	12% 8% 27% 31% 19% 3	712
	11th to 20th	Day	16% 6% 20% 31% 21% 5%	559
	21st to end	Day	26% 8% 22% 27% 12% 4	627
September	1st to 10th	Day	25% 11% 25% 21% 15% 3	570
	11th to 20th	Day	21% 8% 26% 27% 14% 3	570
	21st to end	Day	25% 9% 21% 28% 16% 2	562
October	1st to 10th	Day	28% 14% 21% 25% 10% 1	530
	11th to 20th	Day	32% 15% 31% 19% 3	411
	21st to end	Day	33% 13% 32% 15% 6%	363
November	1st to 10th	Day	32% 16% 28% 19% 5%	330
	11th to 20th	Day	27% 25% 29% 13% 5%	256
	21st to end	Day	28% 21% 35% 14% 2	220
December	1st to 10th	Day	23% 25% 27% 14% 10%	220
	11th to 20th	Day	23% 17% 40% 13% 6% 1	220
	21st to end	Day	28% 18% 36% 11% 7%	242
January	1st to 10th	Night	20% 16% 36% 22% 5%	1050
	11th to 20th	Night	19% 15% 36% 24% 5%	1050
	21st to end	Night	18% 11% 35% 28% 7% 1	1155
February	1st to 10th	Night	17% 14% 40% 24% 5% 1	973
	11th to 20th	Night	16% 14% 37% 24% 8% 1	823
	21st to end	Night	18% 13% 35% 27% 5%	692
March	1st to 10th	Night	17% 11% 37% 28% 7% 1	840
	11th to 20th	Night	21% 12% 35% 25% 6% 1	840
	21st to end	Night	17% 11% 34% 29% 9% 1	883
April	1st to 10th	Night	26% 9% 29% 26% 8% 2	630
	11th to 20th	Night	26% 8% 25% 30% 9% 1	623
	21st to end	Night	22% 9% 27% 27% 14% 1	630
May	1st to 10th	Night	19% 7% 24% 38% 11% 1	630
	11th to 20th	Night	21% 7% 26% 29% 14% 3	611
	21st to end	Night	16% 7% 26% 36% 15%	455
June	1st to 10th	Night	16% 5% 25% 39% 15% 1	420
	11th to 20th	Night	20% 8% 20% 38% 14% 1	420
	21st to end	Night	16% 5% 21% 34% 21% 3	420
July	1st to 10th	Night	14% 3 20% 39% 23% 2	410
	11th to 20th	Night	17% 4 15% 39% 23% 2	551
	21st to end	Night	21% 4 15% 35% 21% 3	690
August	1st to 10th	Night	18% 5% 17% 34% 24% 2	627
	11th to 20th	Night	14% 4 15% 38% 26% 4	624
	21st to end	Night	22% 5% 22% 31% 19% 3	693
September	1st to 10th	Night	20% 6% 24% 28% 18% 4	651
	11th to 20th	Night	21% 7% 24% 31% 15% 2	840
	21st to end	Night	25% 8% 20% 30% 15% 2	833
October	1st to 10th	Night	28% 8% 28% 23% 12% 1	800
	11th to 20th	Night	34% 13% 27% 20% 6%	800
	21st to end	Night	34% 13% 26% 23% 5%	880
November	1st to 10th	Night	32% 14% 30% 19% 5%	820
	11th to 20th	Night	30% 17% 29% 18% 6% 1	840
	21st to end	Night	29% 16% 32% 19% 4	971
December	1st to 10th	Night	25% 15% 34% 20% 5% 1	1050
	11th to 20th	Night	22% 17% 37% 17% 6% 1	1050
	21st to end	Night	28% 16% 31% 19% 5%	1155

Page generated at 2026-09-26 04:18:39. Version ac07

Copyright © 2026 Attilla Danko.