Saint-Sauveur
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Sauveur 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% 11% 4 9% 5% 5% 5% 4 5% 6% 31%	131277
	Night	14% 11% 4 9% 5% 5% 4 4 5% 6% 32%	130235
Transparency	Day	51% 6% 12% 19% 10% 1	134709
	Night	52% 6% 12% 19% 10% 1	134890
Seeing	Day	24% 18% 32% 19% 7% 2	16132
	Night	22% 14% 31% 24% 8% 1	25248

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	11% 19% 6% 14% 6% 4 5% 3 4 5% 23%	4661
	11th to 20th	Day	9% 17% 9% 17% 8% 5% 4 3 4 4 21%	4650
	21st to end	Day	6% 12% 7% 15% 8% 7% 6% 5% 5% 5% 24%	5124
February	1st to 10th	Day	11% 18% 3 12% 7% 5% 5% 3 4 6% 26%	1855
	11th to 20th	Day	10% 18% 5% 12% 5% 5% 4 4 5% 6% 27%	1922
	21st to end	Day	14% 16% 5% 11% 7% 5% 5% 3 4 5% 26%	1730
March	1st to 10th	Day	17% 17% 5% 12% 6% 5% 4 3 4 4 24%	4576
	11th to 20th	Day	9% 14% 5% 11% 5% 5% 5% 3 5% 7% 31%	4817
	21st to end	Day	17% 13% 3 9% 5% 4 4 3 4 5% 34%	5924
April	1st to 10th	Day	20% 13% 3 9% 5% 4 3 3 4 5% 32%	2400
	11th to 20th	Day	20% 10% 3 8% 4 3 4 4 4 6% 34%	2374
	21st to end	Day	21% 11% 3 8% 5% 4 4 3 5% 5% 31%	2550
May	1st to 10th	Day	25% 11% 4 9% 5% 5% 5% 3 5% 6% 23%	6346
	11th to 20th	Day	20% 9% 3 8% 5% 4 4 4 6% 8% 30%	6318
	21st to end	Day	23% 9% 2 7% 5% 5% 5% 4 5% 7% 29%	6949
June	1st to 10th	Day	21% 8% 3 8% 5% 5% 5% 4 6% 7% 28%	2800
	11th to 20th	Day	15% 7% 3 7% 6% 5% 5% 4 7% 8% 34%	2800
	21st to end	Day	21% 9% 2 9% 5% 5% 5% 5% 6% 6% 27%	2800
July	1st to 10th	Day	14% 6% 3 8% 6% 6% 6% 5% 6% 8% 30%	6360
	11th to 20th	Day	12% 5% 2 6% 4 5% 6% 5% 8% 8% 39%	6360
	21st to end	Day	10% 6% 2 6% 4 4 5% 4 6% 9% 45%	6926
August	1st to 10th	Day	14% 5% 2 7% 5% 6% 6% 6% 7% 8% 33%	4563
	11th to 20th	Day	14% 6% 3 7% 5% 4 5% 5% 7% 8% 35%	4151
	21st to end	Day	15% 5% 2 7% 5% 4 5% 3 6% 8% 38%	4312
September	1st to 10th	Day	14% 6% 2 6% 3 5% 4 4 7% 8% 42%	2400
	11th to 20th	Day	13% 5% 2 7% 4 3 4 3 6% 6% 48%	2335
	21st to end	Day	18% 8% 3 5% 4 4 4 3 6% 6% 41%	2200
October	1st to 10th	Day	20% 7% 2 6% 5% 4 4 4 5% 6% 37%	2035
	11th to 20th	Day	20% 10% 3 8% 5% 5% 4 4 5% 6% 30%	1970
	21st to end	Day	24% 11% 3 7% 5% 4 4 3 5% 6% 28%	1980
November	1st to 10th	Day	14% 11% 3 8% 6% 5% 5% 4 6% 6% 32%	1851
	11th to 20th	Day	17% 13% 4 8% 5% 4 5% 3 6% 6% 28%	1764
	21st to end	Day	20% 15% 4 8% 5% 5% 5% 4 5% 6% 22%	1680
December	1st to 10th	Day	17% 17% 8% 13% 5% 5% 5% 3 3 5% 19%	2680
	11th to 20th	Day	16% 15% 7% 11% 5% 4 4 3 4 5% 26%	3066
	21st to end	Day	20% 16% 5% 9% 4 4 4 3 4 4 26%	4048
January	1st to 10th	Night	10% 19% 8% 13% 6% 5% 4 4 4 5% 23%	8234
	11th to 20th	Night	8% 15% 8% 19% 8% 5% 4 3 4 5% 20%	8235
	21st to end	Night	6% 12% 5% 14% 7% 7% 5% 4 6% 6% 26%	9057
February	1st to 10th	Night	10% 13% 5% 12% 7% 6% 5% 4 6% 5% 27%	2761
	11th to 20th	Night	10% 13% 5% 12% 6% 5% 5% 4 6% 6% 30%	2583
	21st to end	Night	12% 13% 5% 11% 7% 5% 4 3 5% 5% 30%	2076
March	1st to 10th	Night	18% 15% 5% 10% 5% 4 4 3 4 5% 28%	5484
	11th to 20th	Night	10% 15% 4 9% 4 4 5% 4 6% 8% 31%	5292
	21st to end	Night	15% 10% 4 9% 6% 5% 4 4 5% 6% 33%	5008
April	1st to 10th	Night	21% 11% 3 7% 5% 4 4 3 5% 6% 32%	2000
	11th to 20th	Night	18% 8% 2 7% 5% 4 4 4 5% 6% 37%	1975
	21st to end	Night	20% 7% 3 7% 4 3 5% 3 4 6% 36%	1850
May	1st to 10th	Night	22% 10% 4 9% 6% 5% 5% 4 5% 6% 26%	3622
	11th to 20th	Night	20% 9% 3 7% 4 4 4 3 5% 7% 34%	3575
	21st to end	Night	21% 10% 3 7% 6% 4 5% 3 6% 6% 29%	3926
June	1st to 10th	Night	19% 8% 3 6% 4 5% 4 4 6% 9% 33%	1600
	11th to 20th	Night	17% 7% 2 5% 5% 5% 4 4 5% 7% 38%	1600
	21st to end	Night	19% 8% 1 6% 5% 4 4 3 7% 6% 36%	1600
July	1st to 10th	Night	13% 6% 2 8% 5% 6% 6% 5% 7% 8% 35%	3600
	11th to 20th	Night	13% 5% 3 6% 4 4 5% 4 6% 8% 44%	3600
	21st to end	Night	9% 5% 2 5% 4 5% 5% 4 6% 8% 48%	3926
August	1st to 10th	Night	12% 5% 3 7% 4 5% 5% 4 6% 9% 40%	2586
	11th to 20th	Night	14% 6% 2 6% 4 4 4 3 6% 6% 44%	2863
	21st to end	Night	15% 6% 3 6% 4 4 4 3 5% 7% 43%	3586
September	1st to 10th	Night	10% 5% 2 6% 4 4 4 4 5% 7% 48%	2000
	11th to 20th	Night	12% 5% 2 5% 4 3 4 3 5% 8% 50%	2065
	21st to end	Night	16% 6% 2 5% 3 4 4 3 5% 6% 46%	2200
October	1st to 10th	Night	16% 7% 3 7% 4 5% 4 3 5% 6% 41%	2363
	11th to 20th	Night	19% 8% 3 7% 4 3 5% 3 5% 7% 36%	2430
	21st to end	Night	21% 10% 3 7% 5% 4 4 4 5% 6% 31%	2860
November	1st to 10th	Night	16% 10% 4 8% 5% 5% 5% 4 6% 7% 31%	2667
	11th to 20th	Night	16% 11% 4 8% 5% 4 4 5% 5% 6% 33%	2853
	21st to end	Night	17% 15% 4 9% 5% 4 4 4 5% 6% 27%	2940
December	1st to 10th	Night	14% 13% 6% 10% 7% 5% 5% 4 6% 7% 22%	4720
	11th to 20th	Night	21% 13% 4 10% 5% 5% 4 3 4 4 27%	5348
	21st to end	Night	20% 19% 5% 9% 4 3 3 2 3 4 29%	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	62% 6% 10% 16% 5%	4662
	11th to 20th	Day	66% 5% 6% 13% 9% 2	4680
	21st to end	Day	59% 7% 9% 13% 12% 1	5124
February	1st to 10th	Day	59% 5% 8% 18% 8% 2	1855
	11th to 20th	Day	58% 4 11% 16% 10% 1	1931
	21st to end	Day	61% 4 8% 15% 10% 2	1730
March	1st to 10th	Day	62% 5% 7% 12% 11% 3	4579
	11th to 20th	Day	52% 5% 16% 14% 11% 2	4817
	21st to end	Day	53% 4 6% 16% 19% 2	5924
April	1st to 10th	Day	55% 4 8% 17% 13% 3	2400
	11th to 20th	Day	51% 4 9% 21% 13% 2	2374
	21st to end	Day	54% 5% 8% 17% 12% 3	2550
May	1st to 10th	Day	61% 6% 7% 17% 8% 1	6357
	11th to 20th	Day	51% 9% 15% 16% 8% 2	6322
	21st to end	Day	53% 6% 11% 17% 12% 1	6949
June	1st to 10th	Day	53% 6% 10% 17% 12% 2	2800
	11th to 20th	Day	45% 7% 12% 21% 12% 3	2800
	21st to end	Day	55% 8% 11% 17% 9% 1	2800
July	1st to 10th	Day	48% 8% 14% 23% 7%	6290
	11th to 20th	Day	37% 8% 15% 30% 10%	6285
	21st to end	Day	35% 6% 17% 33% 9%	6728
August	1st to 10th	Day	45% 8% 18% 22% 8%	4549
	11th to 20th	Day	42% 8% 16% 27% 6%	4193
	21st to end	Day	42% 8% 15% 20% 13% 1	4312
September	1st to 10th	Day	39% 6% 14% 28% 12%	2400
	11th to 20th	Day	35% 6% 15% 31% 13% 1	2335
	21st to end	Day	43% 5% 14% 25% 12% 1	2200
October	1st to 10th	Day	42% 6% 16% 27% 9%	3308
	11th to 20th	Day	44% 6% 16% 24% 9% 1	3186
	21st to end	Day	45% 5% 23% 17% 9% 1	3180
November	1st to 10th	Day	50% 7% 14% 19% 9% 1	1851
	11th to 20th	Day	55% 4 15% 15% 10% 1	1764
	21st to end	Day	61% 6% 14% 13% 4 1	1680
December	1st to 10th	Day	68% 5% 10% 13% 4	2680
	11th to 20th	Day	60% 4 10% 17% 9%	3066
	21st to end	Day	62% 5% 8% 15% 9%	4048
January	1st to 10th	Night	63% 5% 11% 14% 6% 1	8234
	11th to 20th	Night	65% 5% 12% 11% 6% 1	8280
	21st to end	Night	56% 7% 9% 13% 14% 1	9057
February	1st to 10th	Night	57% 5% 10% 19% 8% 1	2761
	11th to 20th	Night	53% 5% 12% 19% 9% 1	2585
	21st to end	Night	56% 4 9% 18% 11% 2	2076
March	1st to 10th	Night	59% 4 8% 14% 12% 4	5494
	11th to 20th	Night	50% 7% 13% 16% 11% 3	5293
	21st to end	Night	52% 4 8% 21% 12% 3	5008
April	1st to 10th	Night	53% 4 8% 18% 15% 2	2000
	11th to 20th	Night	48% 5% 9% 22% 15% 2	1975
	21st to end	Night	50% 5% 8% 20% 14% 3	1850
May	1st to 10th	Night	56% 7% 10% 18% 7% 2	3628
	11th to 20th	Night	48% 8% 13% 19% 10% 2	3576
	21st to end	Night	53% 6% 10% 16% 13% 1	3927
June	1st to 10th	Night	48% 6% 12% 21% 13% 1	1600
	11th to 20th	Night	44% 6% 11% 23% 13% 3	1600
	21st to end	Night	47% 8% 11% 20% 13% 1	1600
July	1st to 10th	Night	44% 8% 18% 21% 8%	3560
	11th to 20th	Night	37% 7% 18% 31% 7%	3552
	21st to end	Night	33% 6% 17% 31% 12%	3809
August	1st to 10th	Night	40% 8% 16% 28% 9%	2576
	11th to 20th	Night	39% 7% 18% 27% 8%	2887
	21st to end	Night	40% 7% 16% 23% 12% 2	3586
September	1st to 10th	Night	35% 8% 14% 28% 15% 1	2000
	11th to 20th	Night	34% 5% 14% 34% 12% 1	2065
	21st to end	Night	39% 6% 12% 28% 15%	2200
October	1st to 10th	Night	41% 5% 15% 25% 12% 1	3870
	11th to 20th	Night	41% 7% 14% 27% 11%	3953
	21st to end	Night	44% 6% 20% 18% 11% 2	4610
November	1st to 10th	Night	51% 6% 14% 21% 7% 1	2667
	11th to 20th	Night	51% 5% 14% 19% 9% 2	2853
	21st to end	Night	58% 6% 13% 17% 6% 1	2940
December	1st to 10th	Night	60% 7% 13% 15% 4	4720
	11th to 20th	Night	60% 5% 8% 15% 11% 1	5348
	21st to end	Night	62% 4 7% 14% 13% 1	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	20% 23% 38% 15% 4	220
	11th to 20th	Day	29% 20% 36% 10% 4	220
	21st to end	Day	20% 24% 38% 14% 4	242
February	1st to 10th	Day	29% 28% 33% 10% 1	313
	11th to 20th	Day	23% 27% 39% 11% 1	409
	21st to end	Day	26% 24% 34% 14% 2	446
March	1st to 10th	Day	30% 22% 30% 15% 3	540
	11th to 20th	Day	25% 27% 31% 13% 3 1	528
	21st to end	Day	30% 22% 27% 14% 6% 1	550
April	1st to 10th	Day	33% 19% 28% 13% 6% 1	500
	11th to 20th	Day	34% 19% 26% 13% 7% 1	492
	21st to end	Day	30% 22% 29% 14% 4 1	500
May	1st to 10th	Day	27% 20% 34% 14% 5% 1	503
	11th to 20th	Day	24% 19% 31% 21% 5% 1	527
	21st to end	Day	25% 19% 30% 19% 6%	573
June	1st to 10th	Day	24% 18% 34% 17% 6% 1	530
	11th to 20th	Day	18% 20% 35% 18% 8% 2	530
	21st to end	Day	27% 13% 34% 17% 7% 2	530
July	1st to 10th	Day	15% 11% 37% 25% 10% 2	525
	11th to 20th	Day	16% 12% 37% 27% 7% 1	524
	21st to end	Day	14% 11% 36% 28% 10% 1	576
August	1st to 10th	Day	15% 9% 31% 31% 12% 2	526
	11th to 20th	Day	13% 9% 29% 30% 13% 6%	519
	21st to end	Day	17% 14% 29% 22% 12% 6%	583
September	1st to 10th	Day	18% 11% 33% 23% 11% 5%	530
	11th to 20th	Day	11% 11% 27% 26% 18% 7%	530
	21st to end	Day	21% 14% 26% 23% 12% 4	530
October	1st to 10th	Day	23% 18% 25% 22% 10% 2	530
	11th to 20th	Day	24% 16% 33% 19% 7% 1	513
	21st to end	Day	32% 15% 30% 19% 5%	462
November	1st to 10th	Day	31% 19% 28% 18% 4 1	425
	11th to 20th	Day	26% 22% 33% 16% 4	304
	21st to end	Day	30% 26% 30% 13% 2	220
December	1st to 10th	Day	27% 17% 35% 16% 4	220
	11th to 20th	Day	29% 23% 35% 11% 1 1	220
	21st to end	Day	33% 22% 27% 12% 4 2	242
January	1st to 10th	Night	23% 18% 35% 21% 3	840
	11th to 20th	Night	23% 21% 30% 21% 4	840
	21st to end	Night	17% 17% 38% 22% 6% 1	924
February	1st to 10th	Night	19% 19% 37% 21% 4 1	840
	11th to 20th	Night	21% 19% 39% 17% 3 1	823
	21st to end	Night	21% 16% 35% 25% 2	692
March	1st to 10th	Night	24% 19% 34% 20% 3	840
	11th to 20th	Night	24% 18% 34% 18% 5%	829
	21st to end	Night	23% 17% 33% 22% 5% 1	880
April	1st to 10th	Night	28% 17% 29% 23% 4	800
	11th to 20th	Night	24% 15% 34% 22% 5%	791
	21st to end	Night	26% 15% 34% 18% 7%	650
May	1st to 10th	Night	25% 13% 33% 21% 6% 2	415
	11th to 20th	Night	21% 12% 30% 29% 8% 1	394
	21st to end	Night	20% 9% 39% 25% 7%	433
June	1st to 10th	Night	24% 10% 31% 28% 7%	400
	11th to 20th	Night	23% 8% 30% 30% 10% 1	400
	21st to end	Night	21% 8% 27% 31% 13% 1	400
July	1st to 10th	Night	11% 8% 31% 35% 13% 1	390
	11th to 20th	Night	11% 6% 27% 43% 13%	388
	21st to end	Night	13% 5% 26% 43% 11% 1	438
August	1st to 10th	Night	13% 5% 22% 42% 17% 2	398
	11th to 20th	Night	11% 5% 27% 33% 22% 2	579
	21st to end	Night	15% 7% 28% 32% 16% 2	880
September	1st to 10th	Night	13% 8% 30% 35% 13% 1	800
	11th to 20th	Night	15% 8% 25% 30% 21% 2	800
	21st to end	Night	19% 9% 25% 30% 16% 2	800
October	1st to 10th	Night	22% 11% 29% 27% 11% 1	800
	11th to 20th	Night	24% 13% 30% 25% 8% 1	800
	21st to end	Night	26% 15% 31% 23% 5%	880
November	1st to 10th	Night	24% 18% 28% 23% 6% 1	820
	11th to 20th	Night	23% 16% 33% 20% 7% 1	840
	21st to end	Night	28% 20% 28% 19% 4 1	840
December	1st to 10th	Night	26% 18% 32% 18% 5%	840
	11th to 20th	Night	28% 21% 28% 18% 4 1	840
	21st to end	Night	32% 18% 30% 16% 4	924

Page generated at 2026-03-15 02:23:55. Version ac07

Copyright © 2026 Attilla Danko.