Morin-Heights
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Morin-Heights clear sky chart from 2005-11-06 to 2024-04-10.

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	17% 11% 4 8% 6% 3 5% 5% 5% 6% 30%	82927
	Night	16% 11% 4 8% 6% 3 4 4 5% 6% 32%	85850
Transparency	Day	53% 6% 11% 19% 10% 1	82632
	Night	52% 6% 12% 19% 10% 1	85679
Seeing	Day	23% 17% 31% 19% 7% 2	13700
	Night	22% 14% 31% 24% 8% 1	22867

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% 9% 3 4 3 3 5% 21%	2517
	11th to 20th	Day	12% 15% 7% 13% 12% 4 4 3 4 5% 22%	2520
	21st to end	Day	11% 16% 8% 12% 7% 3 5% 6% 5% 6% 21%	2772
February	1st to 10th	Day	12% 17% 5% 11% 9% 3 5% 4 4 6% 24%	1682
	11th to 20th	Day	11% 17% 6% 10% 6% 4 5% 4 5% 5% 26%	1729
	21st to end	Day	15% 15% 6% 9% 7% 3 5% 4 4 5% 25%	1570
March	1st to 10th	Day	17% 16% 6% 10% 6% 3 4 4 4 5% 25%	3116
	11th to 20th	Day	12% 18% 6% 11% 7% 3 4 4 4 5% 26%	3334
	21st to end	Day	13% 11% 3 7% 6% 3 4 4 5% 6% 38%	4129
April	1st to 10th	Day	21% 12% 4 7% 6% 2 3 4 4 5% 31%	2270
	11th to 20th	Day	21% 9% 3 6% 5% 3 4 4 4 6% 34%	2134
	21st to end	Day	22% 10% 4 7% 5% 3 4 4 4 6% 30%	2295
May	1st to 10th	Day	20% 9% 4 7% 6% 3 6% 4 4 5% 32%	2520
	11th to 20th	Day	20% 8% 4 6% 6% 3 4 4 5% 6% 34%	2478
	21st to end	Day	20% 7% 3 5% 5% 4 6% 5% 4 6% 34%	2725
June	1st to 10th	Day	22% 8% 3 6% 6% 4 5% 6% 6% 7% 27%	2520
	11th to 20th	Day	16% 6% 3 6% 7% 3 6% 5% 6% 7% 34%	2520
	21st to end	Day	23% 8% 3 8% 6% 4 5% 5% 5% 7% 27%	2520
July	1st to 10th	Day	14% 5% 3 5% 6% 4 7% 5% 6% 7% 38%	2520
	11th to 20th	Day	15% 6% 3 6% 6% 4 6% 6% 6% 9% 33%	2520
	21st to end	Day	13% 7% 3 6% 6% 4 6% 6% 7% 8% 33%	2744
August	1st to 10th	Day	14% 6% 3 6% 7% 4 6% 6% 7% 7% 34%	2506
	11th to 20th	Day	13% 6% 3 6% 6% 4 6% 6% 8% 8% 35%	2296
	21st to end	Day	15% 5% 3 6% 6% 4 5% 4 5% 9% 39%	2376
September	1st to 10th	Day	16% 6% 2 5% 5% 3 4 5% 6% 7% 40%	2160
	11th to 20th	Day	15% 5% 3 5% 4 3 4 4 5% 7% 44%	2105
	21st to end	Day	19% 6% 3 5% 4 3 4 4 5% 6% 40%	1980
October	1st to 10th	Day	22% 8% 2 6% 5% 3 4 5% 5% 6% 34%	1828
	11th to 20th	Day	23% 10% 4 7% 7% 3 5% 5% 4 6% 26%	1778
	21st to end	Day	25% 12% 4 6% 5% 3 4 4 4 6% 26%	1782
November	1st to 10th	Day	15% 10% 4 7% 6% 3 5% 5% 6% 6% 33%	1671
	11th to 20th	Day	19% 12% 5% 9% 5% 3 4 5% 6% 6% 26%	1592
	21st to end	Day	21% 13% 6% 8% 6% 3 5% 5% 5% 6% 23%	1520
December	1st to 10th	Day	21% 18% 6% 9% 7% 3 4 4 3 5% 19%	1520
	11th to 20th	Day	19% 14% 6% 11% 6% 3 4 4 4 5% 24%	1906
	21st to end	Day	22% 19% 7% 9% 5% 3 4 4 4 4 21%	2772
January	1st to 10th	Night	14% 16% 7% 12% 7% 3 5% 4 4 6% 23%	4429
	11th to 20th	Night	10% 13% 7% 13% 10% 5% 5% 4 5% 6% 24%	4440
	21st to end	Night	11% 15% 7% 13% 8% 5% 5% 4 4 5% 23%	4884
February	1st to 10th	Night	12% 13% 6% 11% 7% 4 5% 5% 5% 6% 26%	2494
	11th to 20th	Night	11% 12% 6% 10% 7% 4 5% 4 5% 6% 29%	2336
	21st to end	Night	13% 14% 5% 10% 7% 2 5% 4 5% 6% 29%	1884
March	1st to 10th	Night	18% 12% 5% 8% 6% 3 5% 4 4 5% 31%	3724
	11th to 20th	Night	13% 18% 5% 10% 5% 3 3 4 5% 5% 28%	3621
	21st to end	Night	13% 10% 4 7% 7% 4 4 4 3 6% 38%	3502
April	1st to 10th	Night	21% 10% 4 6% 6% 3 4 3 4 6% 32%	1900
	11th to 20th	Night	18% 7% 2 6% 6% 3 5% 4 5% 5% 38%	1775
	21st to end	Night	21% 8% 2 7% 5% 3 5% 4 5% 6% 35%	1670
May	1st to 10th	Night	19% 9% 3 6% 7% 3 4 4 4 6% 35%	1450
	11th to 20th	Night	18% 8% 3 6% 5% 3 4 4 4 7% 39%	1415
	21st to end	Night	16% 7% 2 5% 5% 3 4 4 5% 8% 40%	1550
June	1st to 10th	Night	20% 8% 3 5% 5% 3 3 6% 5% 10% 32%	1440
	11th to 20th	Night	18% 6% 3 5% 6% 3 4 5% 5% 8% 38%	1440
	21st to end	Night	19% 7% 2 4 6% 4 5% 5% 5% 7% 37%	1440
July	1st to 10th	Night	11% 6% 2 5% 6% 3 4 4 6% 8% 45%	1440
	11th to 20th	Night	12% 6% 2 5% 6% 3 5% 5% 6% 9% 42%	1440
	21st to end	Night	12% 5% 3 5% 6% 3 5% 5% 7% 7% 43%	1574
August	1st to 10th	Night	11% 6% 2 5% 4 2 6% 5% 6% 10% 42%	1432
	11th to 20th	Night	10% 6% 3 6% 5% 3 4 4 6% 7% 46%	1584
	21st to end	Night	14% 5% 2 5% 5% 4 4 4 5% 7% 46%	1980
September	1st to 10th	Night	11% 6% 2 6% 5% 3 4 5% 5% 6% 47%	1800
	11th to 20th	Night	14% 5% 2 4 4 3 3 4 6% 7% 47%	1854
	21st to end	Night	18% 5% 2 4 3 2 4 4 5% 7% 44%	1980
October	1st to 10th	Night	17% 7% 3 6% 5% 4 4 4 5% 5% 39%	2131
	11th to 20th	Night	21% 9% 3 6% 5% 3 5% 4 4 6% 34%	2182
	21st to end	Night	23% 10% 3 6% 6% 3 4 4 5% 6% 29%	2574
November	1st to 10th	Night	17% 9% 5% 7% 6% 3 5% 4 6% 7% 30%	2407
	11th to 20th	Night	17% 10% 4 8% 6% 3 5% 5% 5% 6% 31%	2586
	21st to end	Night	19% 14% 5% 8% 6% 3 3 4 5% 5% 27%	2660
December	1st to 10th	Night	17% 16% 6% 10% 7% 4 5% 4 5% 7% 20%	2660
	11th to 20th	Night	20% 14% 6% 8% 7% 3 4 4 4 6% 25%	3288
	21st to end	Night	23% 19% 5% 8% 6% 3 3 3 4 4 22%	4884

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	64% 8% 10% 13% 4 1	2518
	11th to 20th	Day	62% 7% 9% 15% 7% 1	2520
	21st to end	Day	62% 8% 11% 12% 7% 1	2772
February	1st to 10th	Day	60% 5% 8% 18% 7% 2	1682
	11th to 20th	Day	59% 5% 11% 15% 9% 1	1738
	21st to end	Day	61% 4 9% 15% 9% 3	1570
March	1st to 10th	Day	61% 6% 7% 16% 9% 1	3119
	11th to 20th	Day	58% 4 11% 13% 10% 3	3334
	21st to end	Day	46% 5% 7% 21% 18% 3	4129
April	1st to 10th	Day	56% 4 9% 17% 12% 3	2270
	11th to 20th	Day	50% 4 9% 22% 13% 2	2134
	21st to end	Day	56% 5% 8% 16% 12% 4	2295
May	1st to 10th	Day	53% 4 7% 20% 13% 3	2520
	11th to 20th	Day	49% 5% 10% 17% 16% 3	2482
	21st to end	Day	49% 6% 10% 20% 14% 2	2725
June	1st to 10th	Day	53% 6% 11% 17% 11% 2	2520
	11th to 20th	Day	46% 7% 12% 20% 12% 3	2520
	21st to end	Day	56% 8% 11% 16% 9% 1	2520
July	1st to 10th	Day	41% 9% 14% 26% 10% 1	2450
	11th to 20th	Day	43% 8% 14% 24% 10%	2445
	21st to end	Day	45% 8% 16% 22% 9%	2591
August	1st to 10th	Day	45% 9% 16% 23% 7%	2492
	11th to 20th	Day	42% 10% 16% 23% 9% 1	2296
	21st to end	Day	42% 7% 15% 23% 13% 1	2376
September	1st to 10th	Day	41% 6% 14% 26% 13%	2160
	11th to 20th	Day	37% 6% 14% 29% 12% 1	2105
	21st to end	Day	43% 6% 15% 26% 11%	1980
October	1st to 10th	Day	49% 5% 12% 23% 11% 1	1828
	11th to 20th	Day	57% 7% 13% 17% 6% 1	1778
	21st to end	Day	59% 4 14% 14% 7% 1	1782
November	1st to 10th	Day	49% 7% 14% 20% 9% 1	1671
	11th to 20th	Day	56% 4 15% 15% 9%	1592
	21st to end	Day	60% 6% 15% 14% 4 1	1520
December	1st to 10th	Day	67% 6% 11% 11% 5%	1520
	11th to 20th	Day	61% 4 13% 15% 6%	1906
	21st to end	Day	68% 5% 8% 13% 6%	2772
January	1st to 10th	Night	61% 7% 15% 12% 4	4429
	11th to 20th	Night	57% 7% 18% 13% 5% 1	4440
	21st to end	Night	61% 8% 11% 11% 7% 1	4884
February	1st to 10th	Night	58% 5% 10% 19% 7% 1	2494
	11th to 20th	Night	53% 6% 13% 19% 9% 1	2338
	21st to end	Night	56% 4 10% 17% 11% 2	1884
March	1st to 10th	Night	55% 5% 10% 17% 9% 3	3734
	11th to 20th	Night	57% 6% 9% 14% 12% 2	3622
	21st to end	Night	49% 4 7% 23% 13% 4	3502
April	1st to 10th	Night	53% 4 8% 19% 14% 2	1900
	11th to 20th	Night	47% 5% 9% 23% 15% 2	1775
	21st to end	Night	51% 5% 8% 20% 13% 3	1670
May	1st to 10th	Night	51% 4 7% 19% 14% 4	1450
	11th to 20th	Night	45% 6% 9% 18% 18% 4	1416
	21st to end	Night	43% 7% 11% 21% 16% 3	1551
June	1st to 10th	Night	48% 6% 13% 22% 11% 1	1440
	11th to 20th	Night	45% 6% 10% 23% 13% 3	1440
	21st to end	Night	46% 9% 12% 21% 13%	1440
July	1st to 10th	Night	35% 9% 15% 26% 14% 1	1400
	11th to 20th	Night	39% 7% 14% 29% 10%	1392
	21st to end	Night	38% 8% 17% 25% 12%	1486
August	1st to 10th	Night	36% 10% 18% 26% 10%	1422
	11th to 20th	Night	36% 9% 16% 27% 11%	1584
	21st to end	Night	37% 8% 16% 27% 12%	1980
September	1st to 10th	Night	36% 8% 14% 26% 15% 1	1800
	11th to 20th	Night	36% 6% 14% 33% 11% 1	1854
	21st to end	Night	39% 6% 12% 30% 13%	1980
October	1st to 10th	Night	46% 5% 11% 24% 13% 1	2131
	11th to 20th	Night	50% 6% 15% 21% 8%	2182
	21st to end	Night	55% 6% 14% 17% 8% 1	2574
November	1st to 10th	Night	51% 6% 15% 21% 7% 1	2407
	11th to 20th	Night	52% 5% 15% 18% 8% 2	2586
	21st to end	Night	57% 6% 13% 17% 6% 1	2660
December	1st to 10th	Night	64% 6% 12% 13% 4	2660
	11th to 20th	Night	60% 5% 10% 16% 7% 1	3288
	21st to end	Night	66% 5% 8% 15% 5%	4884

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% 20% 39% 17% 4	180
	11th to 20th	Day	28% 17% 38% 12% 5% 1	180
	21st to end	Day	20% 23% 37% 15% 4 1	198
February	1st to 10th	Day	34% 26% 32% 8% 1	257
	11th to 20th	Day	22% 29% 39% 10% 1	336
	21st to end	Day	28% 24% 30% 16% 2	382
March	1st to 10th	Day	28% 20% 31% 17% 3	460
	11th to 20th	Day	23% 27% 32% 14% 4 1	460
	21st to end	Day	28% 23% 28% 14% 6% 1	506
April	1st to 10th	Day	32% 18% 30% 14% 6% 1	457
	11th to 20th	Day	32% 19% 25% 15% 7% 1	412
	21st to end	Day	30% 20% 30% 14% 4 1	420
May	1st to 10th	Day	26% 19% 34% 15% 5% 1	423
	11th to 20th	Day	24% 18% 32% 20% 4 1	447
	21st to end	Day	23% 21% 32% 19% 5%	485
June	1st to 10th	Day	26% 18% 34% 16% 6% 1	450
	11th to 20th	Day	19% 19% 33% 19% 9% 2	450
	21st to end	Day	27% 12% 32% 19% 8% 2	450
July	1st to 10th	Day	14% 10% 36% 27% 11% 2	445
	11th to 20th	Day	16% 11% 36% 27% 8% 2	444
	21st to end	Day	15% 9% 35% 29% 11% 1	488
August	1st to 10th	Day	15% 10% 31% 29% 13% 2	446
	11th to 20th	Day	13% 9% 30% 29% 13% 6%	439
	21st to end	Day	18% 14% 29% 20% 13% 6%	495
September	1st to 10th	Day	17% 10% 33% 24% 10% 5%	450
	11th to 20th	Day	13% 12% 29% 25% 15% 6%	450
	21st to end	Day	21% 14% 26% 23% 12% 4	450
October	1st to 10th	Day	25% 19% 24% 21% 10% 1	450
	11th to 20th	Day	26% 16% 31% 19% 7% 1	439
	21st to end	Day	33% 14% 30% 18% 5%	396
November	1st to 10th	Day	28% 18% 29% 19% 4 1	365
	11th to 20th	Day	25% 24% 32% 15% 4	252
	21st to end	Day	27% 24% 32% 15% 2	180
December	1st to 10th	Day	29% 17% 32% 18% 4 1	180
	11th to 20th	Day	29% 24% 33% 12% 1 1	180
	21st to end	Day	34% 25% 24% 12% 4 1	198
January	1st to 10th	Night	24% 17% 34% 22% 3	760
	11th to 20th	Night	23% 20% 32% 21% 4	760
	21st to end	Night	16% 16% 39% 22% 6% 1	836
February	1st to 10th	Night	20% 18% 38% 20% 4 1	760
	11th to 20th	Night	20% 19% 40% 17% 3 1	743
	21st to end	Night	22% 17% 33% 25% 2	628
March	1st to 10th	Night	23% 18% 34% 22% 3	760
	11th to 20th	Night	24% 18% 34% 19% 5%	760
	21st to end	Night	22% 16% 33% 22% 6% 1	836
April	1st to 10th	Night	27% 17% 28% 23% 4	760
	11th to 20th	Night	24% 14% 33% 23% 5%	711
	21st to end	Night	26% 15% 33% 19% 7% 1	590
May	1st to 10th	Night	24% 13% 34% 21% 6% 2	370
	11th to 20th	Night	21% 12% 32% 27% 7% 1	354
	21st to end	Night	20% 8% 40% 25% 7%	389
June	1st to 10th	Night	26% 8% 31% 28% 7%	360
	11th to 20th	Night	24% 7% 29% 29% 11% 1	360
	21st to end	Night	20% 7% 26% 32% 14% 1	360
July	1st to 10th	Night	11% 9% 31% 34% 14% 1	350
	11th to 20th	Night	11% 6% 27% 41% 14%	348
	21st to end	Night	14% 4 26% 42% 12% 2	394
August	1st to 10th	Night	14% 5% 21% 42% 16% 2	358
	11th to 20th	Night	11% 6% 26% 33% 23% 3	520
	21st to end	Night	15% 6% 29% 31% 17% 2	792
September	1st to 10th	Night	13% 8% 30% 35% 13% 1	720
	11th to 20th	Night	16% 8% 26% 30% 18% 2	720
	21st to end	Night	20% 9% 25% 28% 16% 2	720
October	1st to 10th	Night	23% 11% 29% 27% 10% 1	720
	11th to 20th	Night	25% 12% 29% 24% 8% 1	720
	21st to end	Night	27% 15% 31% 22% 5%	792
November	1st to 10th	Night	24% 17% 29% 23% 7% 1	740
	11th to 20th	Night	23% 16% 34% 19% 8% 1	760
	21st to end	Night	28% 19% 28% 19% 5% 1	760
December	1st to 10th	Night	27% 18% 33% 17% 5%	760
	11th to 20th	Night	28% 20% 29% 18% 4 1	760
	21st to end	Night	32% 18% 31% 16% 4	836

Page generated at 2024-04-07 09:28:10. Version ac07

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