Lake Manitoba Narrows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Manitoba Narrows clear sky chart from 2005-11-06 to 2026-03-03.

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	10% 8% 3 8% 5% 5% 5% 4 6% 8% 38%	134939
	Night	9% 9% 4 9% 6% 5% 5% 4 6% 7% 34%	135030
Transparency	Day	42% 7% 17% 25% 9% 1	134639
	Night	47% 7% 14% 22% 9% 1	134913
Seeing	Day	14% 6% 24% 32% 19% 5%	18063
	Night	15% 5% 27% 35% 16% 2	28187

By Month

Percentage Cloud Cover NW (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	4 15% 6% 11% 7% 8% 9% 6% 7% 7% 19%	4125
	11th to 20th	Day	4 9% 5% 13% 9% 7% 10% 8% 10% 7% 18%	4179
	21st to end	Day	3 10% 5% 10% 7% 6% 8% 5% 8% 10% 28%	5188
February	1st to 10th	Day	8% 10% 5% 12% 9% 6% 7% 7% 7% 7% 21%	1680
	11th to 20th	Day	7% 10% 3 8% 6% 6% 8% 6% 7% 8% 31%	1841
	21st to end	Day	6% 9% 3 10% 8% 7% 7% 6% 6% 8% 31%	1694
March	1st to 10th	Day	8% 8% 3 9% 7% 7% 7% 5% 6% 9% 32%	4520
	11th to 20th	Day	8% 9% 3 8% 6% 6% 6% 5% 7% 8% 33%	4933
	21st to end	Day	9% 7% 3 8% 5% 6% 6% 4 6% 7% 39%	5527
April	1st to 10th	Day	8% 9% 3 7% 5% 4 5% 4 6% 7% 41%	2461
	11th to 20th	Day	11% 10% 4 7% 5% 5% 5% 4 6% 6% 38%	2572
	21st to end	Day	11% 7% 2 7% 5% 4 5% 4 6% 7% 41%	2600
May	1st to 10th	Day	12% 7% 2 5% 4 3 4 3 6% 6% 48%	6220
	11th to 20th	Day	18% 7% 3 7% 5% 5% 5% 4 5% 6% 35%	6755
	21st to end	Day	12% 5% 2 5% 3 3 4 3 5% 6% 52%	7428
June	1st to 10th	Day	15% 8% 2 7% 4 4 4 3 5% 8% 40%	3000
	11th to 20th	Day	13% 6% 2 6% 5% 5% 5% 4 7% 7% 39%	3000
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 5% 6% 8% 40%	3000
July	1st to 10th	Day	8% 5% 2 5% 4 4 4 4 7% 9% 47%	6800
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 6% 9% 48%	6800
	21st to end	Day	8% 3 1 5% 4 4 4 4 7% 9% 50%	7265
August	1st to 10th	Day	8% 4 2 5% 4 5% 6% 5% 7% 10% 45%	4552
	11th to 20th	Day	11% 5% 2 5% 3 4 4 4 6% 9% 48%	4206
	21st to end	Day	13% 5% 2 6% 4 4 4 3 6% 9% 45%	4675
September	1st to 10th	Day	11% 6% 2 6% 4 4 4 3 6% 8% 46%	2485
	11th to 20th	Day	16% 7% 2 6% 5% 4 4 4 6% 8% 37%	2200
	21st to end	Day	12% 8% 2 6% 4 4 5% 4 6% 6% 42%	2200
October	1st to 10th	Day	14% 7% 3 7% 4 4 4 4 5% 7% 42%	3402
	11th to 20th	Day	11% 10% 2 7% 4 4 5% 3 5% 9% 39%	3005
	21st to end	Day	13% 13% 4 9% 5% 5% 6% 4 6% 6% 29%	3190
November	1st to 10th	Day	19% 15% 5% 11% 5% 3 4 2 4 6% 26%	1712
	11th to 20th	Day	11% 14% 6% 15% 7% 5% 4 4 5% 6% 24%	1610
	21st to end	Day	10% 17% 4 13% 6% 4 5% 3 5% 5% 27%	1470
December	1st to 10th	Day	9% 12% 7% 13% 8% 11% 8% 5% 6% 5% 16%	2360
	11th to 20th	Day	8% 14% 3 11% 7% 5% 5% 6% 8% 9% 23%	2709
	21st to end	Day	4 9% 5% 15% 9% 7% 5% 4 6% 5% 31%	3575
January	1st to 10th	Night	5% 13% 6% 14% 8% 7% 7% 5% 6% 7% 23%	8799
	11th to 20th	Night	5% 11% 5% 14% 9% 7% 10% 7% 7% 7% 17%	8735
	21st to end	Night	5% 11% 5% 11% 7% 7% 8% 6% 8% 9% 23%	9026
February	1st to 10th	Night	8% 13% 5% 11% 6% 6% 6% 4 7% 7% 27%	2940
	11th to 20th	Night	5% 9% 4 8% 6% 6% 6% 6% 7% 8% 35%	2665
	21st to end	Night	6% 9% 4 10% 7% 7% 5% 5% 5% 8% 33%	2129
March	1st to 10th	Night	9% 12% 4 9% 6% 5% 5% 5% 6% 8% 32%	5398
	11th to 20th	Night	6% 8% 4 8% 6% 5% 4 4 7% 7% 40%	5027
	21st to end	Night	9% 11% 3 8% 6% 5% 5% 4 6% 7% 36%	5393
April	1st to 10th	Night	8% 9% 3 7% 6% 5% 4 4 6% 8% 40%	1939
	11th to 20th	Night	13% 9% 4 9% 6% 5% 4 4 5% 7% 34%	1779
	21st to end	Night	12% 8% 3 8% 6% 4 5% 4 6% 7% 37%	1800
May	1st to 10th	Night	13% 8% 3 7% 4 5% 5% 4 6% 7% 39%	3745
	11th to 20th	Night	16% 7% 3 9% 6% 5% 5% 4 6% 7% 33%	3161
	21st to end	Night	11% 5% 2 5% 4 4 4 3 5% 6% 51%	3470
June	1st to 10th	Night	15% 7% 3 7% 5% 5% 4 4 7% 8% 36%	1400
	11th to 20th	Night	15% 5% 2 7% 5% 4 4 4 7% 11% 37%	1400
	21st to end	Night	13% 5% 2 5% 5% 4 5% 6% 7% 9% 39%	1400
July	1st to 10th	Night	6% 3 1 4 4 4 4 4 7% 10% 52%	3180
	11th to 20th	Night	8% 4 2 6% 4 4 5% 4 7% 10% 47%	3180
	21st to end	Night	7% 4 2 5% 4 4 4 4 6% 10% 51%	3598
August	1st to 10th	Night	11% 4 2 5% 4 5% 6% 4 7% 8% 44%	2608
	11th to 20th	Night	8% 4 2 4 3 4 4 4 7% 10% 49%	2853
	21st to end	Night	12% 4 2 5% 4 4 4 3 5% 8% 48%	3234
September	1st to 10th	Night	11% 4 1 6% 4 3 4 4 6% 9% 48%	1911
	11th to 20th	Night	13% 7% 3 6% 5% 4 4 4 5% 8% 42%	2200
	21st to end	Night	13% 6% 3 7% 4 4 4 3 5% 9% 43%	2200
October	1st to 10th	Night	15% 7% 2 5% 2 3 3 3 4 8% 46%	3745
	11th to 20th	Night	9% 9% 3 7% 5% 5% 5% 4 6% 9% 39%	4128
	21st to end	Night	10% 11% 3 8% 6% 5% 4 4 6% 7% 36%	4610
November	1st to 10th	Night	15% 15% 4 11% 6% 6% 4 4 5% 6% 25%	2806
	11th to 20th	Night	9% 18% 5% 15% 8% 4 4 3 5% 4 25%	3008
	21st to end	Night	11% 14% 6% 14% 7% 5% 5% 4 5% 7% 23%	3150
December	1st to 10th	Night	10% 14% 6% 14% 10% 7% 6% 3 5% 6% 18%	5050
	11th to 20th	Night	7% 12% 5% 13% 7% 6% 5% 6% 6% 6% 27%	5718
	21st to end	Night	6% 9% 4 13% 7% 6% 6% 5% 7% 7% 30%	7645

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	61% 7% 11% 15% 6%	4125
	11th to 20th	Day	57% 7% 11% 19% 7%	4200
	21st to end	Day	48% 7% 14% 26% 6%	5188
February	1st to 10th	Day	57% 8% 14% 12% 8% 1	1680
	11th to 20th	Day	47% 8% 16% 21% 8%	1850
	21st to end	Day	50% 7% 12% 21% 11%	1694
March	1st to 10th	Day	46% 8% 17% 19% 9% 1	4520
	11th to 20th	Day	44% 11% 15% 23% 8%	4935
	21st to end	Day	41% 8% 14% 27% 10%	5527
April	1st to 10th	Day	40% 7% 15% 24% 13% 1	2461
	11th to 20th	Day	45% 6% 13% 21% 14% 1	2572
	21st to end	Day	40% 8% 16% 26% 9% 2	2600
May	1st to 10th	Day	34% 6% 13% 29% 17% 1	6220
	11th to 20th	Day	47% 8% 12% 23% 8% 1	6759
	21st to end	Day	32% 7% 11% 23% 22% 6%	7428
June	1st to 10th	Day	42% 8% 16% 24% 9% 1	3000
	11th to 20th	Day	41% 8% 18% 22% 10% 1	3000
	21st to end	Day	39% 10% 20% 24% 6%	3000
July	1st to 10th	Day	31% 7% 28% 27% 6%	6726
	11th to 20th	Day	32% 7% 20% 37% 4	6719
	21st to end	Day	29% 7% 25% 32% 7%	7061
August	1st to 10th	Day	32% 8% 20% 32% 8%	4536
	11th to 20th	Day	33% 7% 24% 33% 4	4245
	21st to end	Day	35% 7% 24% 28% 6%	4674
September	1st to 10th	Day	35% 8% 19% 29% 9% 1	2485
	11th to 20th	Day	44% 9% 19% 22% 5%	2200
	21st to end	Day	40% 9% 17% 26% 9%	2200
October	1st to 10th	Day	42% 6% 15% 31% 6%	3402
	11th to 20th	Day	42% 6% 13% 31% 7%	3005
	21st to end	Day	53% 7% 16% 19% 5%	3190
November	1st to 10th	Day	60% 6% 12% 16% 5% 1	1712
	11th to 20th	Day	59% 10% 13% 13% 5%	1610
	21st to end	Day	59% 6% 14% 17% 3 1	1470
December	1st to 10th	Day	67% 8% 13% 8% 4	2360
	11th to 20th	Day	54% 6% 17% 17% 6%	2710
	21st to end	Day	53% 6% 11% 18% 12% 1	3575
January	1st to 10th	Night	59% 6% 10% 19% 7%	8800
	11th to 20th	Night	61% 6% 9% 17% 6%	8776
	21st to end	Night	52% 8% 13% 22% 5%	9026
February	1st to 10th	Night	53% 6% 13% 19% 8%	2940
	11th to 20th	Night	42% 8% 17% 23% 9%	2666
	21st to end	Night	48% 6% 12% 24% 10%	2129
March	1st to 10th	Night	48% 7% 16% 18% 9% 2	5398
	11th to 20th	Night	39% 8% 14% 24% 15% 1	5027
	21st to end	Night	44% 7% 10% 28% 10% 1	5393
April	1st to 10th	Night	40% 6% 13% 22% 17% 2	1939
	11th to 20th	Night	48% 5% 9% 21% 15% 3	1779
	21st to end	Night	44% 7% 12% 23% 12% 3	1800
May	1st to 10th	Night	41% 8% 12% 21% 17% 1	3745
	11th to 20th	Night	48% 7% 13% 21% 10% 1	3161
	21st to end	Night	32% 7% 11% 20% 23% 7%	3470
June	1st to 10th	Night	42% 8% 14% 24% 10% 1	1400
	11th to 20th	Night	38% 9% 16% 23% 12% 2	1400
	21st to end	Night	37% 13% 19% 24% 6% 1	1400
July	1st to 10th	Night	26% 7% 26% 35% 7%	3145
	11th to 20th	Night	31% 7% 19% 38% 5%	3138
	21st to end	Night	28% 8% 23% 30% 10% 1	3498
August	1st to 10th	Night	35% 9% 17% 27% 12%	2600
	11th to 20th	Night	28% 7% 24% 33% 7% 1	2880
	21st to end	Night	33% 6% 20% 33% 7%	3234
September	1st to 10th	Night	31% 6% 19% 29% 13% 1	1911
	11th to 20th	Night	40% 8% 17% 26% 8% 1	2200
	21st to end	Night	39% 6% 15% 30% 10% 1	2200
October	1st to 10th	Night	37% 5% 13% 29% 15% 1	3745
	11th to 20th	Night	41% 6% 12% 29% 11% 1	4128
	21st to end	Night	46% 8% 16% 27% 4	4610
November	1st to 10th	Night	59% 8% 13% 13% 5% 2	2806
	11th to 20th	Night	62% 7% 13% 12% 5% 1	3008
	21st to end	Night	59% 9% 14% 14% 4	3150
December	1st to 10th	Night	66% 6% 12% 11% 4	5050
	11th to 20th	Night	55% 6% 13% 13% 13%	5716
	21st to end	Night	50% 7% 12% 19% 10% 1	7645

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	10% 4 28% 42% 12% 5%	330
	11th to 20th	Day	10% 5% 29% 39% 14% 3	330
	21st to end	Day	14% 3 28% 35% 17% 4	363
February	1st to 10th	Day	12% 6% 30% 36% 13% 3	330
	11th to 20th	Day	12% 5% 25% 34% 16% 8%	330
	21st to end	Day	6% 5% 27% 35% 23% 3	273
March	1st to 10th	Day	14% 4 25% 34% 19% 4	306
	11th to 20th	Day	12% 5% 28% 33% 17% 4	300
	21st to end	Day	12% 4 24% 33% 23% 5%	355
April	1st to 10th	Day	13% 6% 25% 34% 18% 4	561
	11th to 20th	Day	17% 6% 26% 31% 17% 2	690
	21st to end	Day	15% 4 23% 35% 20% 3	700
May	1st to 10th	Day	14% 6% 21% 35% 20% 4	703
	11th to 20th	Day	17% 5% 24% 30% 19% 5%	725
	21st to end	Day	17% 6% 19% 28% 24% 6%	789
June	1st to 10th	Day	18% 6% 24% 26% 18% 8%	730
	11th to 20th	Day	14% 5% 25% 32% 18% 6%	730
	21st to end	Day	11% 5% 18% 34% 26% 5%	730
July	1st to 10th	Day	9% 6% 18% 33% 25% 9%	721
	11th to 20th	Day	11% 4 22% 32% 22% 8%	718
	21st to end	Day	8% 4 22% 29% 27% 10%	794
August	1st to 10th	Day	9% 5% 20% 31% 26% 10%	726
	11th to 20th	Day	12% 5% 18% 26% 25% 13%	715
	21st to end	Day	14% 7% 20% 30% 23% 6%	803
September	1st to 10th	Day	12% 5% 26% 34% 19% 4	615
	11th to 20th	Day	19% 5% 22% 32% 17% 5%	330
	21st to end	Day	15% 6% 26% 34% 15% 4	330
October	1st to 10th	Day	21% 6% 23% 29% 15% 5%	330
	11th to 20th	Day	22% 8% 32% 25% 11% 3	330
	21st to end	Day	21% 9% 28% 28% 11% 3	363
November	1st to 10th	Day	25% 8% 26% 29% 12% 1	330
	11th to 20th	Day	15% 7% 34% 31% 10% 3	330
	21st to end	Day	17% 6% 31% 36% 9% 2	330
December	1st to 10th	Day	12% 9% 28% 30% 17% 3	330
	11th to 20th	Day	16% 10% 32% 28% 13% 2	330
	21st to end	Day	11% 5% 25% 35% 21% 4	363
January	1st to 10th	Night	11% 4 32% 37% 14% 2	1050
	11th to 20th	Night	14% 6% 29% 36% 13% 1	1050
	21st to end	Night	15% 7% 32% 34% 12% 1	1155
February	1st to 10th	Night	14% 5% 28% 38% 13% 2	1050
	11th to 20th	Night	10% 4 28% 36% 20% 2	1029
	21st to end	Night	9% 4 26% 40% 18% 2	745
March	1st to 10th	Night	14% 5% 25% 35% 18% 2	808
	11th to 20th	Night	11% 4 28% 40% 15% 1	621
	21st to end	Night	17% 5% 25% 35% 16% 3	660
April	1st to 10th	Night	11% 4 27% 41% 15% 2	600
	11th to 20th	Night	17% 4 25% 38% 16%	593
	21st to end	Night	15% 4 27% 40% 14% 1	600
May	1st to 10th	Night	18% 4 24% 38% 15% 1	600
	11th to 20th	Night	16% 4 24% 36% 18% 2	591
	21st to end	Night	20% 5% 16% 38% 20% 2	650
June	1st to 10th	Night	17% 5% 25% 29% 22% 3	600
	11th to 20th	Night	16% 5% 23% 36% 19% 2	600
	21st to end	Night	14% 4 18% 38% 24% 2	600
July	1st to 10th	Night	8% 3 19% 40% 26% 4	585
	11th to 20th	Night	10% 3 21% 39% 23% 3	582
	21st to end	Night	9% 3 20% 36% 27% 5%	657
August	1st to 10th	Night	11% 3 19% 38% 26% 3	597
	11th to 20th	Night	13% 3 19% 33% 27% 5%	594
	21st to end	Night	16% 3 20% 36% 22% 3	660
September	1st to 10th	Night	13% 5% 22% 39% 19% 3	600
	11th to 20th	Night	16% 6% 23% 36% 18% 1	600
	21st to end	Night	15% 5% 28% 34% 18%	600
October	1st to 10th	Night	22% 7% 30% 31% 10% 1	690
	11th to 20th	Night	23% 7% 25% 31% 13% 1	940
	21st to end	Night	21% 8% 28% 32% 8% 2	1100
November	1st to 10th	Night	21% 7% 30% 28% 12% 2	1025
	11th to 20th	Night	18% 9% 32% 29% 9% 2	1050
	21st to end	Night	17% 7% 35% 31% 8% 1	1050
December	1st to 10th	Night	12% 6% 29% 37% 14% 2	1050
	11th to 20th	Night	14% 7% 34% 32% 11% 1	1050
	21st to end	Night	16% 4 28% 34% 15% 3	1155

Page generated at 2026-02-28 00:40:23. Version ac07

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