Mascouche
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mascouche clear sky chart from 2005-11-06 to 2026-03-18.

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	16% 9% 3 8% 5% 5% 5% 4 5% 7% 32%	131243
	Night	16% 11% 4 9% 5% 5% 4 3 5% 6% 31%	130259
Transparency	Day	49% 6% 13% 21% 10% 1	134688
	Night	53% 6% 11% 19% 10% 1	134901
Seeing	Day	20% 10% 28% 25% 12% 4	16173
	Night	22% 8% 29% 31% 10% 1	25264

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% 6% 13% 4 4 4 3 5% 5% 26%	4661
	11th to 20th	Day	11% 16% 6% 13% 7% 5% 5% 3 4 5% 24%	4650
	21st to end	Day	9% 12% 5% 12% 8% 7% 5% 4 5% 6% 26%	5124
February	1st to 10th	Day	13% 16% 3 10% 7% 5% 4 4 4 6% 29%	1830
	11th to 20th	Day	12% 13% 5% 11% 6% 5% 5% 4 5% 6% 28%	1952
	21st to end	Day	16% 15% 4 10% 6% 4 4 3 6% 4 28%	1730
March	1st to 10th	Day	19% 13% 4 10% 6% 5% 4 3 5% 5% 26%	4576
	11th to 20th	Day	11% 13% 4 10% 5% 4 4 3 5% 7% 32%	4760
	21st to end	Day	18% 10% 4 9% 5% 4 4 3 4 5% 33%	5970
April	1st to 10th	Day	20% 12% 3 7% 5% 5% 5% 3 3 5% 32%	2400
	11th to 20th	Day	21% 8% 3 7% 5% 4 4 3 3 6% 37%	2374
	21st to end	Day	22% 8% 4 7% 4 5% 4 3 5% 6% 32%	2570
May	1st to 10th	Day	26% 9% 3 9% 5% 5% 5% 4 5% 6% 25%	6271
	11th to 20th	Day	20% 9% 3 9% 5% 4 4 3 6% 7% 30%	6318
	21st to end	Day	21% 8% 3 6% 5% 5% 5% 4 6% 7% 31%	6949
June	1st to 10th	Day	21% 8% 2 7% 5% 6% 4 4 5% 8% 30%	2800
	11th to 20th	Day	15% 6% 3 7% 4 5% 6% 4 6% 8% 38%	2800
	21st to end	Day	19% 8% 3 8% 6% 5% 5% 4 6% 7% 30%	2800
July	1st to 10th	Day	13% 6% 3 8% 6% 6% 6% 4 7% 8% 33%	6360
	11th to 20th	Day	11% 5% 2 6% 5% 5% 5% 5% 7% 9% 39%	6360
	21st to end	Day	9% 6% 2 5% 4 4 4 4 6% 10% 47%	6926
August	1st to 10th	Day	13% 5% 2 8% 5% 6% 6% 5% 8% 9% 33%	4563
	11th to 20th	Day	13% 6% 3 8% 5% 5% 5% 4 7% 8% 37%	4152
	21st to end	Day	15% 6% 2 6% 4 4 5% 4 6% 8% 40%	4312
September	1st to 10th	Day	11% 5% 2 6% 5% 4 5% 5% 6% 8% 44%	2400
	11th to 20th	Day	13% 4 2 5% 3 3 4 3 6% 6% 51%	2312
	21st to end	Day	16% 6% 2 6% 4 5% 4 2 4 7% 43%	2200
October	1st to 10th	Day	18% 6% 3 7% 3 5% 4 3 5% 7% 39%	2069
	11th to 20th	Day	19% 7% 3 8% 5% 5% 5% 4 5% 6% 31%	1948
	21st to end	Day	23% 10% 3 6% 4 4 4 3 4 6% 32%	1980
November	1st to 10th	Day	15% 11% 3 7% 5% 4 5% 3 6% 7% 34%	1851
	11th to 20th	Day	17% 12% 3 7% 4 4 5% 3 6% 6% 32%	1801
	21st to end	Day	21% 12% 3 7% 5% 5% 6% 4 5% 6% 26%	1680
December	1st to 10th	Day	20% 16% 6% 11% 7% 4 5% 3 4 4 20%	2680
	11th to 20th	Day	19% 13% 5% 9% 5% 4 4 3 5% 4 28%	3066
	21st to end	Day	23% 13% 4 10% 5% 4 4 4 4 5% 24%	4048
January	1st to 10th	Night	12% 17% 6% 16% 6% 5% 4 3 4 4 23%	8234
	11th to 20th	Night	10% 16% 7% 16% 8% 5% 5% 3 4 5% 20%	8235
	21st to end	Night	10% 12% 5% 13% 8% 6% 5% 4 5% 6% 27%	9057
February	1st to 10th	Night	13% 15% 5% 12% 7% 4 4 5% 5% 4 26%	2788
	11th to 20th	Night	14% 11% 5% 10% 5% 5% 4 4 5% 5% 31%	2554
	21st to end	Night	15% 14% 3 9% 6% 4 4 3 4 6% 31%	2076
March	1st to 10th	Night	22% 13% 4 8% 5% 4 4 3 4 4 30%	5484
	11th to 20th	Night	13% 14% 4 9% 5% 4 5% 4 6% 7% 31%	5336
	21st to end	Night	16% 11% 4 9% 6% 5% 5% 3 5% 4 33%	4962
April	1st to 10th	Night	23% 10% 3 7% 4 4 4 3 5% 6% 31%	2000
	11th to 20th	Night	21% 8% 3 6% 5% 3 5% 4 4 5% 36%	1975
	21st to end	Night	21% 10% 2 7% 3 4 4 3 5% 5% 36%	1829
May	1st to 10th	Night	26% 10% 3 8% 5% 4 4 3 4 6% 26%	3700
	11th to 20th	Night	22% 9% 3 7% 5% 4 4 4 5% 7% 31%	3575
	21st to end	Night	19% 10% 3 8% 5% 5% 5% 3 5% 7% 30%	3926
June	1st to 10th	Night	21% 8% 2 6% 6% 4 4 4 5% 8% 33%	1600
	11th to 20th	Night	15% 7% 2 7% 4 4 5% 4 7% 7% 39%	1600
	21st to end	Night	19% 7% 3 7% 5% 4 4 5% 5% 7% 34%	1600
July	1st to 10th	Night	12% 6% 2 8% 5% 6% 6% 5% 8% 10% 33%	3600
	11th to 20th	Night	14% 6% 2 6% 4 5% 5% 4 5% 8% 42%	3600
	21st to end	Night	9% 5% 2 7% 4 5% 5% 4 7% 8% 45%	3926
August	1st to 10th	Night	13% 7% 3 8% 4 5% 5% 4 6% 7% 38%	2586
	11th to 20th	Night	14% 7% 3 7% 4 4 5% 4 5% 7% 39%	2861
	21st to end	Night	16% 7% 3 7% 5% 4 4 4 6% 7% 39%	3586
September	1st to 10th	Night	10% 5% 3 7% 4 5% 4 3 5% 7% 47%	2000
	11th to 20th	Night	13% 6% 2 5% 3 3 3 3 5% 6% 52%	2087
	21st to end	Night	15% 6% 2 6% 5% 4 4 3 4 7% 45%	2200
October	1st to 10th	Night	18% 6% 2 6% 4 4 4 3 5% 6% 43%	2330
	11th to 20th	Night	18% 9% 2 7% 4 5% 4 3 5% 6% 38%	2451
	21st to end	Night	21% 9% 3 7% 5% 5% 4 3 5% 6% 32%	2860
November	1st to 10th	Night	19% 9% 3 7% 5% 5% 4 3 5% 6% 34%	2667
	11th to 20th	Night	18% 10% 3 8% 4 4 4 3 5% 5% 34%	2816
	21st to end	Night	21% 13% 3 8% 5% 4 4 2 4 5% 29%	2940
December	1st to 10th	Night	17% 15% 5% 11% 7% 6% 5% 4 5% 5% 20%	4720
	11th to 20th	Night	23% 13% 4 9% 5% 4 4 3 4 6% 27%	5348
	21st to end	Night	24% 15% 5% 9% 4 3 3 3 5% 5% 24%	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	59% 6% 12% 18% 4	4662
	11th to 20th	Day	61% 6% 9% 14% 9% 1	4680
	21st to end	Day	57% 6% 11% 13% 11% 1	5124
February	1st to 10th	Day	57% 4 10% 20% 7% 2	1830
	11th to 20th	Day	56% 6% 12% 16% 10% 1	1961
	21st to end	Day	58% 4 9% 16% 11% 2	1730
March	1st to 10th	Day	60% 6% 8% 13% 11% 3	4579
	11th to 20th	Day	50% 6% 18% 13% 11% 3	4760
	21st to end	Day	52% 4 8% 16% 18% 2	5970
April	1st to 10th	Day	55% 5% 8% 18% 13% 2	2400
	11th to 20th	Day	50% 4 8% 22% 15% 2	2374
	21st to end	Day	53% 5% 9% 17% 13% 3	2570
May	1st to 10th	Day	58% 7% 8% 18% 7% 1	6282
	11th to 20th	Day	51% 7% 15% 17% 8% 2	6322
	21st to end	Day	50% 7% 11% 19% 12% 1	6949
June	1st to 10th	Day	50% 7% 11% 18% 12% 2	2800
	11th to 20th	Day	42% 7% 12% 24% 13% 3	2800
	21st to end	Day	51% 8% 11% 19% 10% 1	2800
July	1st to 10th	Day	45% 8% 13% 25% 8%	6290
	11th to 20th	Day	37% 8% 14% 30% 11%	6285
	21st to end	Day	32% 7% 15% 36% 9%	6728
August	1st to 10th	Day	44% 8% 17% 22% 8%	4549
	11th to 20th	Day	42% 8% 18% 26% 6%	4194
	21st to end	Day	41% 7% 16% 22% 14% 1	4312
September	1st to 10th	Day	36% 7% 15% 30% 11% 1	2400
	11th to 20th	Day	34% 6% 13% 32% 15% 1	2312
	21st to end	Day	42% 6% 13% 27% 12% 1	2200
October	1st to 10th	Day	42% 7% 15% 26% 9%	3368
	11th to 20th	Day	43% 7% 17% 26% 7%	3151
	21st to end	Day	42% 6% 20% 23% 9% 1	3180
November	1st to 10th	Day	48% 6% 13% 23% 9% 1	1851
	11th to 20th	Day	52% 6% 12% 19% 11%	1801
	21st to end	Day	58% 6% 14% 15% 6% 1	1680
December	1st to 10th	Day	68% 5% 8% 15% 4	2680
	11th to 20th	Day	57% 6% 10% 17% 10%	3066
	21st to end	Day	63% 6% 12% 13% 7%	4048
January	1st to 10th	Night	64% 5% 11% 14% 5% 1	8234
	11th to 20th	Night	65% 7% 9% 13% 6%	8280
	21st to end	Night	58% 5% 9% 14% 13%	9057
February	1st to 10th	Night	60% 5% 9% 17% 8% 1	2788
	11th to 20th	Night	54% 6% 9% 20% 10% 1	2556
	21st to end	Night	55% 5% 9% 18% 12% 2	2076
March	1st to 10th	Night	57% 5% 8% 14% 12% 4	5494
	11th to 20th	Night	52% 6% 13% 14% 12% 2	5337
	21st to end	Night	54% 4 7% 21% 13% 2	4962
April	1st to 10th	Night	54% 4 8% 18% 14% 2	2000
	11th to 20th	Night	51% 4 7% 21% 15% 2	1975
	21st to end	Night	50% 5% 9% 19% 14% 4	1829
May	1st to 10th	Night	59% 7% 9% 17% 7% 2	3706
	11th to 20th	Night	52% 7% 11% 18% 10% 2	3576
	21st to end	Night	52% 6% 10% 17% 14% 1	3927
June	1st to 10th	Night	49% 6% 10% 20% 14% 1	1600
	11th to 20th	Night	43% 7% 13% 21% 14% 3	1600
	21st to end	Night	48% 8% 11% 18% 14% 1	1600
July	1st to 10th	Night	42% 9% 18% 22% 9% 1	3560
	11th to 20th	Night	39% 7% 17% 27% 9%	3552
	21st to end	Night	35% 7% 17% 29% 12%	3809
August	1st to 10th	Night	45% 8% 12% 26% 9%	2576
	11th to 20th	Night	43% 8% 17% 24% 8%	2885
	21st to end	Night	44% 7% 12% 22% 13% 1	3586
September	1st to 10th	Night	37% 7% 13% 27% 15% 1	2000
	11th to 20th	Night	34% 5% 14% 33% 12% 1	2087
	21st to end	Night	40% 7% 10% 28% 15%	2200
October	1st to 10th	Night	41% 7% 15% 25% 11% 1	3811
	11th to 20th	Night	42% 5% 12% 31% 9%	3987
	21st to end	Night	45% 5% 17% 19% 12% 2	4610
November	1st to 10th	Night	51% 5% 11% 22% 9% 1	2667
	11th to 20th	Night	52% 5% 12% 20% 10% 1	2816
	21st to end	Night	60% 5% 10% 18% 7%	2940
December	1st to 10th	Night	66% 5% 11% 13% 4	4720
	11th to 20th	Night	60% 5% 9% 15% 11%	5348
	21st to end	Night	63% 4 8% 15% 10%	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	21% 16% 30% 23% 10%	220
	11th to 20th	Day	24% 18% 30% 23% 4 1	220
	21st to end	Day	16% 14% 34% 24% 9% 2	242
February	1st to 10th	Day	25% 16% 34% 22% 3	300
	11th to 20th	Day	19% 13% 36% 26% 5%	439
	21st to end	Day	25% 10% 36% 24% 5%	446
March	1st to 10th	Day	24% 12% 33% 23% 9%	540
	11th to 20th	Day	23% 12% 34% 24% 5% 1	528
	21st to end	Day	26% 11% 33% 21% 9% 1	550
April	1st to 10th	Day	25% 17% 27% 22% 8% 2	500
	11th to 20th	Day	26% 17% 25% 21% 8% 3	492
	21st to end	Day	28% 11% 32% 20% 7% 2	500
May	1st to 10th	Day	23% 12% 31% 24% 8% 2	503
	11th to 20th	Day	19% 9% 30% 25% 13% 4	527
	21st to end	Day	21% 11% 29% 25% 12% 2	573
June	1st to 10th	Day	22% 10% 27% 27% 12% 2	530
	11th to 20th	Day	15% 11% 26% 31% 14% 3	530
	21st to end	Day	20% 11% 25% 28% 12% 4	530
July	1st to 10th	Day	14% 6% 26% 30% 19% 6%	525
	11th to 20th	Day	14% 6% 27% 32% 17% 4	524
	21st to end	Day	13% 5% 26% 33% 19% 5%	576
August	1st to 10th	Day	13% 6% 21% 32% 21% 6%	526
	11th to 20th	Day	11% 4 20% 31% 22% 11%	519
	21st to end	Day	15% 8% 25% 23% 20% 10%	583
September	1st to 10th	Day	12% 6% 28% 27% 19% 8%	530
	11th to 20th	Day	12% 7% 19% 29% 20% 13%	530
	21st to end	Day	18% 9% 25% 24% 18% 6%	530
October	1st to 10th	Day	18% 11% 28% 23% 16% 5%	530
	11th to 20th	Day	19% 12% 32% 23% 12% 2	500
	21st to end	Day	30% 8% 29% 23% 10%	462
November	1st to 10th	Day	25% 14% 27% 24% 8% 1	425
	11th to 20th	Day	24% 11% 32% 22% 9% 1	341
	21st to end	Day	32% 14% 28% 15% 10%	220
December	1st to 10th	Day	29% 11% 26% 20% 11% 3	220
	11th to 20th	Day	23% 14% 36% 22% 4 1	220
	21st to end	Day	27% 15% 30% 19% 7% 2	242
January	1st to 10th	Night	25% 10% 30% 29% 6%	840
	11th to 20th	Night	24% 10% 33% 26% 7%	840
	21st to end	Night	18% 8% 35% 30% 8% 1	924
February	1st to 10th	Night	20% 8% 36% 29% 7% 1	840
	11th to 20th	Night	21% 9% 36% 28% 5% 1	823
	21st to end	Night	22% 9% 33% 32% 4	692
March	1st to 10th	Night	24% 9% 32% 29% 5%	840
	11th to 20th	Night	25% 10% 32% 25% 7%	829
	21st to end	Night	22% 9% 31% 31% 7%	880
April	1st to 10th	Night	28% 10% 27% 29% 6%	800
	11th to 20th	Night	25% 10% 32% 28% 5%	791
	21st to end	Night	28% 7% 33% 24% 7%	629
May	1st to 10th	Night	24% 8% 28% 32% 7% 1	454
	11th to 20th	Night	23% 8% 27% 34% 8% 1	394
	21st to end	Night	19% 7% 32% 33% 9%	433
June	1st to 10th	Night	24% 6% 23% 37% 10% 1	400
	11th to 20th	Night	18% 6% 26% 38% 12% 1	400
	21st to end	Night	21% 4 26% 36% 13%	400
July	1st to 10th	Night	11% 6% 26% 39% 17% 1	390
	11th to 20th	Night	11% 5% 22% 45% 16% 1	388
	21st to end	Night	13% 3 20% 47% 16% 1	438
August	1st to 10th	Night	14% 5% 13% 46% 22% 1	398
	11th to 20th	Night	14% 4 20% 36% 24% 2	577
	21st to end	Night	16% 4 21% 36% 21% 2	880
September	1st to 10th	Night	15% 4 22% 41% 17% 1	800
	11th to 20th	Night	16% 4 18% 37% 24% 2	800
	21st to end	Night	18% 4 25% 35% 16% 2	800
October	1st to 10th	Night	21% 5% 27% 34% 13% 1	800
	11th to 20th	Night	22% 8% 28% 31% 11% 1	800
	21st to end	Night	25% 9% 30% 29% 6%	880
November	1st to 10th	Night	24% 11% 29% 28% 8%	820
	11th to 20th	Night	23% 9% 32% 25% 10% 1	840
	21st to end	Night	28% 11% 30% 22% 8% 1	840
December	1st to 10th	Night	28% 8% 31% 25% 7%	840
	11th to 20th	Night	28% 11% 31% 24% 5% 1	840
	21st to end	Night	32% 10% 29% 22% 6%	924

Page generated at 2026-03-15 02:23:52. Version ac07

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