Pointe-au-Chêne
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pointe-au-Chêne clear sky chart from 2005-11-06 to 2025-11-18.

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	18% 11% 3 8% 5% 4 4 3 5% 6% 31%	127193
	Night	18% 12% 4 9% 5% 4 4 3 5% 6% 31%	123168
Transparency	Day	34% 38% 8% 14% 6% 1	130635
	Night	35% 38% 7% 12% 7% 1	127813
Seeing	Day	26% 15% 30% 19% 8% 2	15807
	Night	25% 12% 29% 26% 9% 1	24803

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	15% 22% 6% 15% 6% 5% 4 2 3 3 18%	3597
	11th to 20th	Day	14% 17% 7% 14% 7% 4 3 3 5% 5% 20%	3570
	21st to end	Day	11% 19% 8% 12% 5% 6% 5% 4 4 4 22%	3978
February	1st to 10th	Day	14% 17% 4 13% 6% 5% 3 3 4 6% 25%	1800
	11th to 20th	Day	13% 17% 5% 12% 7% 5% 4 3 5% 5% 24%	1805
	21st to end	Day	19% 16% 5% 8% 6% 5% 4 3 4 4 24%	1650
March	1st to 10th	Day	19% 16% 5% 12% 6% 4 4 3 4 5% 24%	4476
	11th to 20th	Day	12% 15% 4 10% 6% 4 4 4 5% 6% 30%	4832
	21st to end	Day	20% 11% 3 7% 5% 4 4 3 4 5% 34%	5873
April	1st to 10th	Day	21% 15% 3 7% 4 4 4 2 4 5% 32%	2400
	11th to 20th	Day	22% 10% 3 7% 4 4 3 3 4 5% 35%	2374
	21st to end	Day	23% 10% 3 7% 5% 4 4 4 5% 5% 30%	2544
May	1st to 10th	Day	25% 10% 3 9% 5% 5% 5% 4 5% 6% 23%	6346
	11th to 20th	Day	20% 9% 3 8% 5% 4 4 4 5% 7% 31%	6318
	21st to end	Day	22% 10% 2 7% 4 4 4 4 5% 7% 31%	6949
June	1st to 10th	Day	24% 8% 3 7% 6% 4 4 3 6% 7% 29%	2800
	11th to 20th	Day	15% 7% 3 6% 5% 6% 5% 5% 6% 8% 36%	2800
	21st to end	Day	22% 7% 3 7% 6% 5% 4 4 6% 8% 28%	2800
July	1st to 10th	Day	15% 7% 3 8% 5% 6% 6% 5% 7% 9% 31%	6360
	11th to 20th	Day	15% 6% 2 6% 4 5% 5% 4 6% 8% 39%	6360
	21st to end	Day	10% 6% 2 6% 3 4 4 3 6% 9% 47%	6926
August	1st to 10th	Day	15% 6% 3 7% 5% 6% 5% 5% 6% 8% 34%	4563
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 6% 8% 38%	4111
	21st to end	Day	17% 5% 2 6% 4 4 5% 4 5% 9% 38%	4312
September	1st to 10th	Day	16% 6% 2 5% 4 4 4 4 5% 7% 43%	2400
	11th to 20th	Day	14% 4 1 5% 3 3 4 3 6% 6% 50%	2357
	21st to end	Day	20% 6% 2 5% 3 4 4 3 5% 7% 41%	2200
October	1st to 10th	Day	22% 8% 2 6% 4 3 5% 3 4 7% 36%	2000
	11th to 20th	Day	24% 9% 4 8% 4 4 4 3 4 6% 28%	2000
	21st to end	Day	25% 12% 4 8% 5% 4 3 3 4 6% 27%	1980
November	1st to 10th	Day	18% 12% 3 7% 5% 5% 3 3 5% 7% 32%	1851
	11th to 20th	Day	21% 13% 4 9% 5% 5% 5% 4 4 6% 25%	1715
	21st to end	Day	23% 16% 4 9% 5% 4 4 4 4 5% 23%	1600
December	1st to 10th	Day	21% 23% 6% 9% 5% 4 4 3 5% 6% 15%	2600
	11th to 20th	Day	19% 19% 5% 9% 4 3 4 3 4 4 24%	2986
	21st to end	Day	22% 18% 4 9% 4 4 4 3 4 4 23%	3960
January	1st to 10th	Night	16% 23% 8% 12% 4 3 3 2 3 4 19%	6349
	11th to 20th	Night	11% 19% 7% 16% 7% 5% 4 3 4 5% 19%	6315
	21st to end	Night	12% 17% 7% 13% 6% 6% 5% 3 4 5% 22%	6973
February	1st to 10th	Night	15% 15% 6% 11% 6% 5% 5% 4 4 5% 25%	2600
	11th to 20th	Night	14% 13% 5% 12% 8% 5% 3 3 4 5% 27%	2480
	21st to end	Night	16% 15% 5% 9% 5% 5% 3 4 4 6% 28%	1980
March	1st to 10th	Night	22% 15% 5% 9% 4 4 3 3 4 4 28%	5364
	11th to 20th	Night	14% 15% 3 7% 4 4 5% 4 6% 7% 31%	5122
	21st to end	Night	19% 11% 4 8% 6% 5% 4 3 4 5% 32%	5059
April	1st to 10th	Night	23% 10% 3 7% 5% 4 4 3 4 5% 32%	2000
	11th to 20th	Night	21% 8% 3 7% 6% 3 4 3 4 6% 35%	1975
	21st to end	Night	22% 9% 3 6% 4 3 5% 3 4 5% 36%	1875
May	1st to 10th	Night	22% 10% 3 8% 5% 5% 5% 4 6% 6% 26%	3594
	11th to 20th	Night	21% 7% 2 7% 4 4 4 3 5% 6% 35%	3575
	21st to end	Night	22% 10% 3 7% 5% 4 4 3 5% 6% 30%	3926
June	1st to 10th	Night	19% 6% 2 7% 5% 4 4 4 7% 9% 31%	1600
	11th to 20th	Night	16% 6% 3 7% 4 4 4 5% 5% 6% 40%	1600
	21st to end	Night	21% 6% 2 7% 5% 4 5% 4 6% 6% 35%	1600
July	1st to 10th	Night	15% 7% 2 7% 5% 6% 5% 5% 7% 8% 33%	3600
	11th to 20th	Night	15% 7% 3 6% 4 4 3 3 6% 7% 42%	3600
	21st to end	Night	11% 5% 2 5% 4 4 4 4 6% 7% 48%	3926
August	1st to 10th	Night	15% 6% 3 7% 5% 4 5% 4 7% 7% 38%	2586
	11th to 20th	Night	18% 6% 1 6% 4 4 4 3 6% 6% 43%	2900
	21st to end	Night	17% 5% 2 6% 4 5% 4 3 5% 6% 42%	3586
September	1st to 10th	Night	13% 5% 2 7% 4 4 4 3 5% 7% 46%	2000
	11th to 20th	Night	16% 5% 1 5% 3 3 3 3 6% 6% 50%	2042
	21st to end	Night	19% 6% 2 4 3 4 4 3 5% 7% 44%	2200
October	1st to 10th	Night	20% 7% 2 6% 4 4 4 3 5% 6% 40%	2396
	11th to 20th	Night	22% 8% 3 7% 5% 4 4 3 5% 6% 34%	2400
	21st to end	Night	25% 10% 3 8% 5% 4 3 3 4 5% 31%	2858
November	1st to 10th	Night	22% 11% 3 7% 4 3 4 3 5% 6% 31%	2667
	11th to 20th	Night	20% 12% 4 8% 6% 4 4 3 4 5% 31%	2836
	21st to end	Night	22% 16% 5% 8% 5% 4 4 3 4 5% 23%	2800
December	1st to 10th	Night	19% 18% 6% 11% 6% 5% 4 4 5% 6% 17%	4580
	11th to 20th	Night	25% 15% 4 9% 4 4 3 2 3 4 25%	5208
	21st to end	Night	25% 18% 4 9% 3 3 3 2 3 4 25%	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	52% 30% 4 9% 3 1	3598
	11th to 20th	Day	48% 29% 7% 11% 5%	3600
	21st to end	Day	50% 30% 5% 7% 7% 1	3978
February	1st to 10th	Day	25% 61% 3 7% 3 1	1800
	11th to 20th	Day	25% 61% 3 7% 5%	1814
	21st to end	Day	25% 62% 3 4 5% 1	1650
March	1st to 10th	Day	48% 30% 4 7% 9% 3	4479
	11th to 20th	Day	38% 30% 12% 9% 9% 1	4832
	21st to end	Day	40% 29% 4 11% 15% 1	5873
April	1st to 10th	Day	22% 62% 3 6% 7% 1	2400
	11th to 20th	Day	21% 61% 2 9% 6% 1	2374
	21st to end	Day	22% 61% 4 7% 6%	2544
May	1st to 10th	Day	47% 31% 5% 13% 4	6357
	11th to 20th	Day	40% 31% 11% 12% 6%	6322
	21st to end	Day	41% 30% 8% 13% 8%	6949
June	1st to 10th	Day	21% 61% 3 9% 6% 1	2800
	11th to 20th	Day	18% 62% 4 9% 6% 1	2800
	21st to end	Day	20% 60% 4 11% 5% 1	2800
July	1st to 10th	Day	39% 27% 11% 19% 5%	6290
	11th to 20th	Day	31% 26% 10% 25% 8%	6285
	21st to end	Day	24% 26% 13% 30% 7%	6728
August	1st to 10th	Day	31% 36% 12% 15% 5%	4549
	11th to 20th	Day	30% 37% 10% 20% 3	4152
	21st to end	Day	27% 37% 12% 16% 8%	4312
September	1st to 10th	Day	17% 57% 7% 13% 6%	2400
	11th to 20th	Day	13% 57% 6% 17% 6% 1	2357
	21st to end	Day	15% 57% 6% 14% 8%	2200
October	1st to 10th	Day	30% 36% 8% 21% 5%	3260
	11th to 20th	Day	26% 37% 11% 21% 5% 1	3240
	21st to end	Day	29% 37% 15% 14% 4	3180
November	1st to 10th	Day	30% 53% 5% 7% 3 1	1851
	11th to 20th	Day	26% 56% 4 9% 5%	1715
	21st to end	Day	30% 58% 5% 5% 3	1600
December	1st to 10th	Day	46% 37% 6% 10% 1	2600
	11th to 20th	Day	46% 32% 5% 11% 6%	2986
	21st to end	Day	48% 27% 6% 13% 6%	3960
January	1st to 10th	Night	53% 27% 9% 8% 3	6349
	11th to 20th	Night	50% 29% 8% 9% 3	6360
	21st to end	Night	49% 30% 5% 6% 9%	6973
February	1st to 10th	Night	24% 62% 3 8% 3	2600
	11th to 20th	Night	23% 60% 3 8% 5%	2482
	21st to end	Night	22% 61% 3 7% 6%	1980
March	1st to 10th	Night	44% 30% 4 9% 10% 3	5374
	11th to 20th	Night	36% 31% 10% 12% 8% 3	5123
	21st to end	Night	42% 28% 5% 15% 8% 1	5059
April	1st to 10th	Night	22% 61% 2 8% 7%	2000
	11th to 20th	Night	21% 62% 2 8% 6%	1975
	21st to end	Night	20% 61% 4 8% 6% 1	1875
May	1st to 10th	Night	44% 32% 7% 14% 3	3600
	11th to 20th	Night	38% 32% 9% 13% 7% 1	3576
	21st to end	Night	44% 29% 7% 12% 8%	3927
June	1st to 10th	Night	19% 61% 4 9% 7%	1600
	11th to 20th	Night	16% 62% 3 10% 8% 1	1600
	21st to end	Night	19% 60% 4 10% 7% 1	1600
July	1st to 10th	Night	39% 27% 14% 15% 6%	3560
	11th to 20th	Night	32% 27% 12% 25% 5%	3552
	21st to end	Night	25% 26% 12% 26% 11%	3809
August	1st to 10th	Night	30% 36% 9% 20% 5%	2576
	11th to 20th	Night	30% 36% 12% 18% 4	2925
	21st to end	Night	28% 36% 10% 16% 8% 2	3586
September	1st to 10th	Night	14% 58% 6% 14% 8%	2000
	11th to 20th	Night	13% 57% 7% 17% 5%	2042
	21st to end	Night	15% 56% 6% 14% 8%	2200
October	1st to 10th	Night	25% 36% 11% 20% 7% 1	3916
	11th to 20th	Night	25% 36% 9% 21% 8%	3899
	21st to end	Night	30% 36% 13% 13% 8%	4608
November	1st to 10th	Night	29% 53% 6% 9% 3	2667
	11th to 20th	Night	26% 55% 5% 9% 5%	2836
	21st to end	Night	28% 57% 5% 7% 3	2800
December	1st to 10th	Night	44% 36% 9% 9% 2	4580
	11th to 20th	Night	46% 31% 3 10% 9% 1	5208
	21st to end	Night	48% 27% 3 10% 11%	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	30% 19% 34% 14% 4	200
	11th to 20th	Day	32% 19% 36% 8% 6%	200
	21st to end	Day	25% 19% 35% 17% 3 1	223
February	1st to 10th	Day	34% 27% 32% 6% 2	300
	11th to 20th	Day	28% 28% 35% 9%	352
	21st to end	Day	33% 19% 30% 16% 2	414
March	1st to 10th	Day	31% 18% 32% 17% 2	500
	11th to 20th	Day	29% 21% 33% 13% 4 1	500
	21st to end	Day	33% 20% 26% 15% 5% 1	550
April	1st to 10th	Day	33% 20% 27% 14% 6% 1	500
	11th to 20th	Day	36% 18% 23% 15% 8% 1	492
	21st to end	Day	34% 19% 31% 10% 5% 1	500
May	1st to 10th	Day	29% 16% 35% 14% 5% 1	503
	11th to 20th	Day	22% 19% 30% 21% 7% 1	527
	21st to end	Day	24% 16% 32% 20% 7% 1	573
June	1st to 10th	Day	26% 12% 35% 19% 7% 1	530
	11th to 20th	Day	18% 14% 35% 20% 10% 2	530
	21st to end	Day	27% 12% 33% 18% 8% 2	530
July	1st to 10th	Day	16% 10% 35% 24% 12% 3	525
	11th to 20th	Day	16% 11% 36% 24% 12% 2	524
	21st to end	Day	16% 11% 32% 28% 11% 2	576
August	1st to 10th	Day	16% 8% 27% 34% 12% 3	526
	11th to 20th	Day	18% 6% 25% 31% 15% 5%	519
	21st to end	Day	18% 13% 26% 23% 15% 6%	583
September	1st to 10th	Day	20% 10% 29% 23% 14% 4	530
	11th to 20th	Day	14% 7% 26% 22% 21% 9%	530
	21st to end	Day	22% 12% 27% 22% 13% 5%	530
October	1st to 10th	Day	25% 14% 23% 23% 11% 3	530
	11th to 20th	Day	28% 18% 29% 18% 6% 1	530
	21st to end	Day	33% 14% 31% 19% 4	462
November	1st to 10th	Day	34% 15% 28% 19% 5%	425
	11th to 20th	Day	30% 19% 34% 11% 5%	273
	21st to end	Day	34% 22% 28% 14% 3	200
December	1st to 10th	Day	34% 13% 35% 15% 4 1	200
	11th to 20th	Day	33% 24% 33% 9% 3	200
	21st to end	Day	32% 19% 30% 13% 4 1	220
January	1st to 10th	Night	29% 14% 35% 19% 4	800
	11th to 20th	Night	28% 16% 30% 20% 6% 1	800
	21st to end	Night	19% 16% 35% 24% 6% 1	880
February	1st to 10th	Night	23% 17% 33% 23% 4	800
	11th to 20th	Night	23% 19% 34% 20% 4	783
	21st to end	Night	25% 15% 33% 23% 3	660
March	1st to 10th	Night	26% 15% 31% 23% 5%	800
	11th to 20th	Night	26% 18% 31% 20% 4	800
	21st to end	Night	26% 13% 30% 24% 7%	880
April	1st to 10th	Night	30% 14% 29% 23% 4	800
	11th to 20th	Night	26% 14% 32% 22% 6%	791
	21st to end	Night	29% 13% 31% 21% 7%	675
May	1st to 10th	Night	25% 11% 31% 25% 7% 2	400
	11th to 20th	Night	23% 10% 29% 30% 9% 1	394
	21st to end	Night	23% 7% 33% 27% 9% 1	433
June	1st to 10th	Night	21% 6% 30% 32% 10%	400
	11th to 20th	Night	21% 7% 27% 34% 11% 1	400
	21st to end	Night	23% 4 27% 32% 14% 1	400
July	1st to 10th	Night	12% 6% 27% 37% 18%	390
	11th to 20th	Night	14% 4 21% 44% 16% 1	388
	21st to end	Night	15% 4 24% 39% 16% 1	438
August	1st to 10th	Night	14% 4 17% 44% 21% 1	398
	11th to 20th	Night	15% 3 19% 35% 26% 2	604
	21st to end	Night	18% 4 22% 36% 18% 2	880
September	1st to 10th	Night	16% 5% 27% 35% 15% 1	800
	11th to 20th	Night	20% 4 19% 30% 24% 3	800
	21st to end	Night	23% 7% 23% 30% 16% 2	800
October	1st to 10th	Night	23% 8% 26% 29% 14%	800
	11th to 20th	Night	27% 11% 28% 27% 7% 1	800
	21st to end	Night	30% 11% 29% 25% 5%	880
November	1st to 10th	Night	29% 11% 27% 24% 7% 1	820
	11th to 20th	Night	26% 15% 32% 18% 8%	829
	21st to end	Night	31% 15% 29% 18% 7%	800
December	1st to 10th	Night	31% 15% 30% 20% 4	800
	11th to 20th	Night	31% 17% 29% 18% 5% 1	800
	21st to end	Night	36% 14% 28% 17% 4	880

Page generated at 2025-11-15 00:55:54. Version ac07

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