Parc du Mont Ste-Anne
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Parc du Mont Ste-Anne clear sky chart from 2005-11-06 to 2024-01-12.

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% 9% 4 7% 6% 4 5% 5% 5% 7% 30%	74529
	Night	17% 10% 4 7% 6% 3 5% 4 5% 6% 32%	75186
Transparency	Day	52% 6% 12% 20% 9% 1	74233
	Night	52% 5% 11% 20% 10% 1	75017
Seeing	Day	24% 17% 31% 20% 7% 1	14217
	Night	22% 14% 28% 27% 8% 1	22762

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	12% 15% 5% 9% 9% 4 4 6% 5% 6% 25%	1517
	11th to 20th	Day	11% 13% 6% 12% 7% 4 4 5% 6% 5% 27%	1448
	21st to end	Day	8% 10% 5% 9% 6% 4 6% 8% 6% 5% 33%	1584
February	1st to 10th	Day	7% 13% 6% 12% 8% 4 6% 6% 6% 6% 26%	1448
	11th to 20th	Day	12% 13% 5% 11% 9% 4 5% 5% 4 5% 27%	1712
	21st to end	Day	11% 12% 4 11% 8% 5% 6% 4 5% 7% 28%	1480
March	1st to 10th	Day	12% 11% 5% 9% 9% 4 5% 5% 5% 6% 29%	1797
	11th to 20th	Day	14% 12% 6% 8% 6% 3 5% 6% 4 4 31%	1898
	21st to end	Day	13% 13% 5% 8% 6% 4 5% 5% 4 5% 32%	2294
April	1st to 10th	Day	20% 11% 4 8% 7% 3 4 4 5% 6% 27%	2160
	11th to 20th	Day	19% 7% 4 6% 5% 3 5% 5% 5% 5% 36%	2238
	21st to end	Day	23% 9% 3 6% 6% 4 5% 4 5% 6% 30%	2340
May	1st to 10th	Day	22% 6% 3 6% 5% 3 5% 4 4 7% 34%	2384
	11th to 20th	Day	18% 8% 3 6% 7% 4 5% 4 5% 6% 33%	2478
	21st to end	Day	19% 6% 3 7% 6% 3 6% 5% 6% 7% 32%	2810
June	1st to 10th	Day	19% 6% 3 6% 7% 4 7% 6% 6% 8% 27%	2700
	11th to 20th	Day	20% 7% 3 5% 6% 4 5% 5% 6% 7% 32%	2700
	21st to end	Day	22% 8% 4 7% 6% 4 5% 5% 6% 7% 26%	2700
July	1st to 10th	Day	14% 7% 4 6% 7% 4 6% 6% 6% 10% 31%	2621
	11th to 20th	Day	15% 6% 3 7% 6% 5% 7% 6% 8% 8% 30%	2520
	21st to end	Day	15% 7% 3 6% 6% 4 7% 7% 8% 9% 28%	2744
August	1st to 10th	Day	15% 7% 2 7% 7% 4 7% 8% 8% 9% 25%	2489
	11th to 20th	Day	14% 7% 3 6% 7% 4 6% 5% 7% 9% 32%	2304
	21st to end	Day	15% 7% 3 6% 6% 4 6% 6% 6% 8% 34%	2493
September	1st to 10th	Day	17% 6% 3 5% 6% 4 4 4 6% 9% 35%	2160
	11th to 20th	Day	17% 6% 2 5% 5% 3 4 4 5% 7% 43%	1990
	21st to end	Day	21% 8% 2 6% 4 2 4 4 5% 6% 38%	1980
October	1st to 10th	Day	17% 9% 3 6% 7% 4 4 5% 5% 6% 34%	1980
	11th to 20th	Day	21% 10% 3 8% 6% 5% 5% 5% 5% 6% 26%	1643
	21st to end	Day	26% 11% 3 7% 6% 4 4 4 4 6% 25%	1782
November	1st to 10th	Day	16% 11% 5% 7% 4 3 6% 5% 5% 7% 31%	1671
	11th to 20th	Day	19% 11% 4 8% 7% 3 6% 6% 4 5% 27%	1694
	21st to end	Day	18% 16% 6% 8% 6% 3 4 5% 5% 5% 25%	1340
December	1st to 10th	Day	20% 14% 7% 9% 6% 4 4 4 3 5% 25%	1330
	11th to 20th	Day	18% 12% 4 9% 7% 5% 5% 4 4 4 28%	1668
	21st to end	Day	17% 13% 4 8% 7% 3 4 4 5% 6% 29%	2432
January	1st to 10th	Night	12% 15% 6% 11% 9% 4 6% 5% 5% 5% 23%	2649
	11th to 20th	Night	12% 13% 6% 11% 8% 4 5% 4 5% 6% 27%	2541
	21st to end	Night	8% 10% 6% 9% 6% 5% 6% 5% 6% 7% 31%	2772
February	1st to 10th	Night	9% 11% 5% 9% 9% 4 6% 5% 6% 7% 31%	2511
	11th to 20th	Night	9% 14% 6% 11% 6% 4 5% 5% 5% 6% 28%	2130
	21st to end	Night	12% 13% 4 9% 8% 4 5% 5% 5% 7% 28%	1776
March	1st to 10th	Night	11% 12% 5% 8% 7% 4 5% 5% 5% 7% 31%	2150
	11th to 20th	Night	14% 13% 5% 7% 6% 3 6% 4 5% 6% 31%	2061
	21st to end	Night	14% 11% 4 7% 6% 3 5% 5% 5% 6% 34%	2061
April	1st to 10th	Night	21% 13% 4 7% 5% 3 4 4 5% 5% 29%	1800
	11th to 20th	Night	17% 8% 2 4 4 4 6% 5% 6% 7% 37%	1669
	21st to end	Night	24% 8% 3 7% 5% 3 3 3 4 5% 34%	1620
May	1st to 10th	Night	22% 8% 3 7% 4 2 4 5% 5% 6% 33%	1592
	11th to 20th	Night	21% 5% 3 5% 6% 3 6% 5% 5% 6% 36%	1415
	21st to end	Night	23% 5% 2 5% 4 3 4 5% 5% 6% 38%	1463
June	1st to 10th	Night	18% 8% 3 7% 7% 3 6% 5% 7% 8% 28%	1260
	11th to 20th	Night	19% 6% 2 5% 4 2 5% 4 6% 6% 39%	1260
	21st to end	Night	24% 7% 4 6% 5% 3 4 4 3 7% 33%	1260
July	1st to 10th	Night	17% 5% 3 5% 6% 3 4 5% 5% 9% 38%	1335
	11th to 20th	Night	16% 4 3 5% 5% 4 6% 5% 8% 8% 37%	1440
	21st to end	Night	15% 6% 3 6% 5% 3 5% 6% 6% 8% 37%	1574
August	1st to 10th	Night	16% 5% 2 5% 5% 3 5% 4 6% 9% 43%	1432
	11th to 20th	Night	16% 6% 3 6% 5% 4 7% 5% 6% 8% 35%	1596
	21st to end	Night	15% 6% 3 4 5% 3 6% 5% 5% 8% 42%	1861
September	1st to 10th	Night	16% 6% 3 5% 5% 3 4 5% 5% 7% 41%	1800
	11th to 20th	Night	19% 6% 2 5% 5% 2 4 4 5% 6% 43%	1970
	21st to end	Night	18% 7% 3 5% 5% 2 4 4 4 5% 43%	1980
October	1st to 10th	Night	18% 8% 2 6% 5% 3 5% 4 4 6% 39%	1980
	11th to 20th	Night	23% 8% 3 6% 6% 3 5% 4 5% 5% 33%	2314
	21st to end	Night	24% 10% 3 6% 5% 3 4 5% 5% 7% 29%	2574
November	1st to 10th	Night	16% 9% 4 7% 5% 3 5% 5% 6% 7% 33%	2407
	11th to 20th	Night	17% 10% 4 6% 4 3 5% 5% 5% 6% 34%	2484
	21st to end	Night	17% 14% 5% 8% 6% 3 5% 5% 5% 6% 27%	2836
December	1st to 10th	Night	18% 14% 6% 9% 8% 4 5% 5% 4 6% 22%	2850
	11th to 20th	Night	19% 12% 5% 9% 7% 3 5% 4 5% 5% 28%	3531
	21st to end	Night	18% 16% 6% 8% 7% 3 4 3 3 4 30%	5232

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% 4 10% 17% 8% 1	1518
	11th to 20th	Day	56% 6% 10% 17% 9% 2	1448
	21st to end	Day	47% 8% 9% 20% 15% 1	1584
February	1st to 10th	Day	57% 5% 9% 17% 10% 3	1448
	11th to 20th	Day	59% 5% 9% 14% 12% 2	1721
	21st to end	Day	55% 6% 5% 20% 11% 3	1480
March	1st to 10th	Day	55% 5% 9% 15% 13% 3	1800
	11th to 20th	Day	54% 6% 8% 17% 13% 3	1898
	21st to end	Day	54% 5% 8% 19% 10% 4	2294
April	1st to 10th	Day	57% 5% 11% 12% 10% 4	2160
	11th to 20th	Day	48% 6% 9% 24% 11% 3	2238
	21st to end	Day	54% 5% 11% 17% 12% 3	2340
May	1st to 10th	Day	50% 5% 12% 18% 13% 2	2384
	11th to 20th	Day	51% 6% 10% 22% 10% 1	2482
	21st to end	Day	50% 7% 11% 21% 11%	2810
June	1st to 10th	Day	53% 7% 12% 20% 7% 1	2700
	11th to 20th	Day	49% 6% 14% 20% 9% 2	2700
	21st to end	Day	56% 6% 13% 16% 8%	2700
July	1st to 10th	Day	46% 8% 18% 22% 6%	2550
	11th to 20th	Day	45% 9% 17% 21% 7%	2445
	21st to end	Day	48% 8% 17% 21% 6%	2591
August	1st to 10th	Day	49% 9% 19% 19% 3	2475
	11th to 20th	Day	45% 7% 20% 20% 7%	2304
	21st to end	Day	45% 8% 14% 24% 9%	2493
September	1st to 10th	Day	44% 5% 15% 24% 10%	2160
	11th to 20th	Day	39% 6% 17% 27% 10% 1	1990
	21st to end	Day	47% 4 13% 26% 10%	1980
October	1st to 10th	Day	49% 5% 10% 25% 10% 1	1980
	11th to 20th	Day	58% 6% 16% 16% 4	1643
	21st to end	Day	60% 5% 10% 17% 7% 1	1782
November	1st to 10th	Day	52% 7% 11% 21% 8% 1	1671
	11th to 20th	Day	57% 6% 8% 19% 8% 1	1694
	21st to end	Day	59% 6% 12% 14% 7% 1	1340
December	1st to 10th	Day	62% 4 10% 15% 7%	1330
	11th to 20th	Day	59% 4 6% 19% 10% 1	1668
	21st to end	Day	58% 4 11% 17% 8% 3	2432
January	1st to 10th	Night	62% 5% 8% 16% 8% 1	2649
	11th to 20th	Night	58% 5% 10% 16% 9% 2	2541
	21st to end	Night	50% 5% 9% 19% 14% 2	2772
February	1st to 10th	Night	51% 6% 9% 21% 11% 2	2511
	11th to 20th	Night	57% 4 10% 15% 12% 1	2132
	21st to end	Night	54% 4 7% 18% 14% 2	1776
March	1st to 10th	Night	52% 5% 10% 18% 12% 2	2160
	11th to 20th	Night	53% 5% 9% 18% 12% 3	2062
	21st to end	Night	52% 4 8% 20% 11% 4	2061
April	1st to 10th	Night	58% 4 7% 16% 13% 4	1800
	11th to 20th	Night	45% 5% 10% 25% 13% 2	1669
	21st to end	Night	54% 4 9% 18% 14% 3	1620
May	1st to 10th	Night	51% 5% 9% 19% 13% 3	1592
	11th to 20th	Night	48% 5% 11% 20% 14% 2	1416
	21st to end	Night	47% 6% 12% 19% 15% 1	1464
June	1st to 10th	Night	53% 5% 12% 21% 8% 1	1260
	11th to 20th	Night	44% 5% 12% 25% 10% 4	1260
	21st to end	Night	53% 6% 13% 17% 11%	1260
July	1st to 10th	Night	43% 5% 20% 23% 8%	1296
	11th to 20th	Night	43% 5% 19% 25% 7% 1	1392
	21st to end	Night	44% 7% 18% 24% 7%	1486
August	1st to 10th	Night	39% 6% 22% 29% 4	1422
	11th to 20th	Night	45% 7% 22% 18% 7%	1596
	21st to end	Night	39% 7% 15% 30% 8%	1861
September	1st to 10th	Night	42% 6% 15% 25% 12% 1	1800
	11th to 20th	Night	42% 5% 18% 27% 8%	1970
	21st to end	Night	43% 5% 11% 27% 12% 1	1980
October	1st to 10th	Night	46% 5% 10% 24% 14% 1	1980
	11th to 20th	Night	53% 5% 13% 22% 7%	2314
	21st to end	Night	54% 5% 13% 19% 8% 1	2574
November	1st to 10th	Night	49% 6% 13% 24% 8% 1	2407
	11th to 20th	Night	50% 6% 12% 20% 11% 1	2484
	21st to end	Night	57% 6% 10% 18% 8% 1	2836
December	1st to 10th	Night	63% 5% 10% 15% 6% 1	2850
	11th to 20th	Night	58% 4 8% 17% 12% 1	3532
	21st to end	Night	60% 2 9% 16% 10% 2	5232

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	22% 23% 35% 13% 7% 1	180
	11th to 20th	Day	22% 29% 32% 12% 5%	162
	21st to end	Day	16% 28% 34% 16% 5% 1	176
February	1st to 10th	Day	27% 33% 31% 6% 3	168
	11th to 20th	Day	21% 24% 35% 16% 5%	400
	21st to end	Day	25% 23% 29% 18% 5%	346
March	1st to 10th	Day	23% 23% 33% 16% 4 1	420
	11th to 20th	Day	26% 19% 31% 16% 6% 1	420
	21st to end	Day	23% 21% 30% 18% 7% 2	462
April	1st to 10th	Day	27% 22% 29% 16% 6% 1	420
	11th to 20th	Day	27% 20% 31% 17% 4 2	412
	21st to end	Day	28% 17% 36% 14% 3 3	420
May	1st to 10th	Day	28% 16% 33% 17% 6% 1	423
	11th to 20th	Day	22% 14% 37% 19% 6% 2	447
	21st to end	Day	24% 21% 31% 18% 7%	570
June	1st to 10th	Day	24% 14% 32% 21% 8% 1	630
	11th to 20th	Day	23% 16% 27% 23% 10% 1	630
	21st to end	Day	23% 13% 27% 27% 8% 1	630
July	1st to 10th	Day	18% 13% 34% 24% 9% 1	545
	11th to 20th	Day	18% 11% 39% 24% 7% 1	444
	21st to end	Day	18% 11% 36% 25% 9% 1	488
August	1st to 10th	Day	17% 13% 33% 25% 9% 2	446
	11th to 20th	Day	16% 11% 33% 27% 12% 3	439
	21st to end	Day	20% 18% 27% 19% 12% 5%	495
September	1st to 10th	Day	21% 14% 28% 25% 8% 4	450
	11th to 20th	Day	22% 13% 32% 19% 10% 4	450
	21st to end	Day	23% 16% 28% 20% 9% 4	450
October	1st to 10th	Day	22% 16% 30% 22% 8% 2	450
	11th to 20th	Day	27% 18% 28% 17% 9% 1	365
	21st to end	Day	39% 15% 24% 16% 5% 1	396
November	1st to 10th	Day	28% 19% 30% 17% 5% 1	365
	11th to 20th	Day	28% 19% 24% 20% 8% 1	370
	21st to end	Day	29% 23% 33% 13% 2	190
December	1st to 10th	Day	27% 17% 27% 22% 7%	180
	11th to 20th	Day	31% 23% 27% 13% 4 1	180
	21st to end	Day	31% 21% 31% 13% 5%	198
January	1st to 10th	Night	21% 17% 31% 26% 4	760
	11th to 20th	Night	20% 17% 32% 24% 6%	727
	21st to end	Night	14% 16% 32% 31% 6% 1	792
February	1st to 10th	Night	14% 21% 33% 26% 6%	720
	11th to 20th	Night	19% 19% 35% 21% 5% 1	703
	21st to end	Night	21% 16% 32% 25% 5% 1	592
March	1st to 10th	Night	18% 17% 35% 24% 5%	720
	11th to 20th	Night	21% 19% 33% 20% 7% 1	720
	21st to end	Night	20% 17% 32% 22% 8% 1	792
April	1st to 10th	Night	29% 16% 27% 22% 6%	720
	11th to 20th	Night	23% 12% 33% 24% 7%	605
	21st to end	Night	29% 11% 29% 24% 7% 1	540
May	1st to 10th	Night	25% 11% 29% 29% 6% 1	512
	11th to 20th	Night	21% 11% 28% 31% 9%	354
	21st to end	Night	25% 9% 31% 27% 7%	389
June	1st to 10th	Night	22% 9% 27% 31% 10% 1	360
	11th to 20th	Night	20% 6% 23% 37% 13% 1	360
	21st to end	Night	24% 7% 19% 39% 11% 1	360
July	1st to 10th	Night	19% 6% 30% 32% 12% 1	350
	11th to 20th	Night	19% 5% 23% 40% 13% 1	348
	21st to end	Night	17% 5% 20% 44% 14% 1	394
August	1st to 10th	Night	18% 3 21% 41% 18% 1	358
	11th to 20th	Night	17% 6% 24% 34% 17% 1	532
	21st to end	Night	17% 9% 24% 34% 15% 2	673
September	1st to 10th	Night	18% 6% 27% 36% 12% 2	720
	11th to 20th	Night	21% 8% 29% 26% 15% 2	720
	21st to end	Night	22% 11% 23% 30% 13% 1	720
October	1st to 10th	Night	22% 12% 26% 29% 10% 1	720
	11th to 20th	Night	27% 11% 25% 27% 10% 1	720
	21st to end	Night	31% 14% 28% 20% 7%	792
November	1st to 10th	Night	23% 17% 29% 22% 7% 1	740
	11th to 20th	Night	23% 19% 24% 24% 9% 1	766
	21st to end	Night	26% 18% 28% 22% 5% 1	850
December	1st to 10th	Night	27% 15% 26% 24% 7% 1	850
	11th to 20th	Night	23% 21% 26% 24% 5% 1	850
	21st to end	Night	27% 19% 28% 19% 7% 1	933

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