Domaine Saint-Bernard
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Domaine Saint-Bernard clear sky chart from 2005-11-06 to 2026-10-14.

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% 12% 4 9% 5% 5% 5% 4 5% 7% 28%	150003
	Night	17% 13% 5% 10% 6% 4 4 3 5% 5% 27%	141715
Transparency	Day	56% 5% 11% 19% 9% 1	153436
	Night	58% 5% 11% 17% 9% 1	146371
Seeing	Day	27% 18% 29% 17% 6% 2	16923
	Night	25% 15% 28% 24% 9% 1	25834

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% 17% 7% 20% 8% 5% 5% 3 4 4 14%	4661
	11th to 20th	Day	11% 22% 8% 19% 10% 3 3 2 3 4 16%	4650
	21st to end	Day	6% 14% 9% 16% 9% 6% 6% 4 6% 6% 18%	5124
February	1st to 10th	Day	10% 19% 6% 15% 9% 5% 4 3 3 5% 22%	1869
	11th to 20th	Day	11% 19% 6% 14% 6% 5% 3 3 4 6% 23%	1895
	21st to end	Day	15% 19% 6% 10% 7% 5% 4 3 5% 4 22%	1730
March	1st to 10th	Day	18% 17% 6% 14% 6% 5% 3 2 3 4 21%	4576
	11th to 20th	Day	15% 15% 6% 11% 5% 4 4 3 4 6% 26%	4902
	21st to end	Day	18% 13% 4 9% 5% 4 4 3 4 5% 31%	6025
April	1st to 10th	Day	20% 16% 5% 8% 5% 3 3 3 4 6% 27%	2520
	11th to 20th	Day	23% 11% 4 7% 5% 4 3 3 4 5% 30%	2494
	21st to end	Day	21% 13% 3 8% 5% 4 4 3 4 5% 30%	2700
May	1st to 10th	Day	23% 12% 4 8% 5% 5% 5% 4 6% 6% 22%	8237
	11th to 20th	Day	21% 9% 3 8% 5% 5% 5% 4 6% 7% 28%	8221
	21st to end	Day	22% 10% 3 7% 5% 5% 5% 3 5% 6% 30%	9060
June	1st to 10th	Day	24% 10% 3 7% 4 5% 5% 4 6% 6% 27%	2940
	11th to 20th	Day	18% 7% 3 7% 6% 5% 5% 5% 6% 7% 31%	2940
	21st to end	Day	23% 8% 3 7% 5% 5% 5% 4 6% 6% 27%	2940
July	1st to 10th	Day	17% 6% 3 7% 5% 5% 5% 4 6% 9% 33%	8280
	11th to 20th	Day	14% 6% 2 6% 4 5% 5% 4 6% 9% 39%	8280
	21st to end	Day	13% 7% 2 6% 4 5% 5% 4 6% 10% 37%	8993
August	1st to 10th	Day	19% 7% 3 8% 6% 6% 5% 4 6% 7% 29%	6483
	11th to 20th	Day	16% 8% 2 7% 4 5% 5% 5% 7% 8% 33%	5950
	21st to end	Day	16% 7% 2 6% 5% 5% 5% 4 6% 9% 34%	6080
September	1st to 10th	Day	18% 6% 2 6% 5% 4 4 4 6% 7% 39%	2520
	11th to 20th	Day	16% 6% 2 5% 3 4 4 3 6% 7% 42%	2469
	21st to end	Day	22% 8% 2 5% 4 4 3 3 5% 7% 38%	2310
October	1st to 10th	Day	24% 11% 2 7% 4 4 4 3 4 6% 32%	2107
	11th to 20th	Day	26% 13% 4 9% 5% 3 4 3 4 5% 24%	2015
	21st to end	Day	26% 16% 4 7% 4 4 3 3 4 5% 23%	1980
November	1st to 10th	Day	19% 16% 5% 8% 4 3 5% 3 4 6% 27%	1851
	11th to 20th	Day	20% 18% 6% 10% 6% 5% 4 4 4 4 20%	1727
	21st to end	Day	22% 18% 7% 13% 6% 4 4 3 2 4 18%	1680
December	1st to 10th	Day	18% 23% 10% 11% 7% 4 3 3 4 4 12%	2680
	11th to 20th	Day	18% 21% 7% 13% 7% 4 4 3 4 4 17%	3066
	21st to end	Day	18% 18% 5% 11% 5% 5% 5% 3 4 5% 21%	4048
January	1st to 10th	Night	11% 21% 10% 16% 6% 4 4 3 4 4 16%	8234
	11th to 20th	Night	10% 20% 9% 21% 12% 5% 3 3 3 4 12%	8235
	21st to end	Night	6% 13% 9% 18% 8% 9% 7% 4 6% 5% 17%	9057
February	1st to 10th	Night	11% 17% 5% 13% 7% 6% 5% 4 4 5% 22%	2749
	11th to 20th	Night	12% 17% 6% 13% 7% 5% 4 3 4 4 23%	2610
	21st to end	Night	14% 17% 7% 11% 6% 4 4 4 5% 5% 24%	2076
March	1st to 10th	Night	20% 15% 5% 12% 5% 4 4 3 4 4 24%	5484
	11th to 20th	Night	14% 15% 4 11% 5% 4 4 4 5% 6% 27%	5262
	21st to end	Night	17% 14% 4 10% 6% 5% 4 3 4 5% 27%	5148
April	1st to 10th	Night	22% 14% 4 7% 5% 4 3 3 4 6% 28%	2100
	11th to 20th	Night	21% 11% 3 6% 4 3 3 3 5% 5% 35%	2075
	21st to end	Night	20% 11% 4 7% 4 4 3 3 4 6% 34%	1936
May	1st to 10th	Night	17% 11% 4 8% 5% 5% 5% 4 6% 7% 26%	4660
	11th to 20th	Night	22% 8% 3 7% 4 4 4 3 5% 8% 32%	4639
	21st to end	Night	22% 11% 3 7% 5% 4 5% 3 5% 6% 30%	5114
June	1st to 10th	Night	18% 8% 3 7% 6% 4 4 4 6% 7% 32%	1680
	11th to 20th	Night	19% 8% 2 6% 4 4 4 4 6% 7% 36%	1680
	21st to end	Night	20% 8% 3 5% 4 5% 5% 4 6% 5% 36%	1680
July	1st to 10th	Night	16% 6% 3 7% 5% 4 6% 4 7% 8% 33%	4680
	11th to 20th	Night	15% 7% 3 5% 3 4 4 3 6% 7% 43%	4680
	21st to end	Night	15% 5% 3 6% 5% 4 5% 4 6% 8% 40%	5084
August	1st to 10th	Night	18% 8% 3 6% 4 4 4 4 6% 7% 35%	3666
	11th to 20th	Night	20% 7% 2 7% 4 4 4 3 5% 6% 38%	4046
	21st to end	Night	21% 7% 2 6% 4 3 4 3 5% 6% 38%	5045
September	1st to 10th	Night	17% 8% 2 4 4 3 4 3 5% 7% 43%	2100
	11th to 20th	Night	17% 5% 1 5% 3 4 4 3 5% 7% 47%	2150
	21st to end	Night	18% 7% 2 6% 3 3 3 4 4 8% 42%	2310
October	1st to 10th	Night	21% 8% 2 6% 5% 4 4 3 5% 5% 38%	2509
	11th to 20th	Night	24% 13% 3 7% 5% 4 4 3 4 5% 29%	2452
	21st to end	Night	26% 13% 4 8% 5% 4 4 3 4 6% 24%	2860
November	1st to 10th	Night	21% 14% 4 8% 4 4 4 3 4 6% 26%	2667
	11th to 20th	Night	18% 17% 6% 10% 6% 5% 4 3 4 6% 21%	2889
	21st to end	Night	21% 21% 6% 11% 6% 4 4 3 4 4 17%	2940
December	1st to 10th	Night	17% 20% 8% 16% 8% 5% 3 3 4 4 12%	4720
	11th to 20th	Night	23% 19% 5% 11% 7% 4 3 2 3 3 20%	5348
	21st to end	Night	20% 21% 5% 11% 5% 4 3 2 3 4 23%	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	73% 3 6% 13% 4	4662
	11th to 20th	Day	75% 2 3 10% 9% 1	4680
	21st to end	Day	65% 5% 8% 10% 11% 1	5124
February	1st to 10th	Day	64% 4 6% 17% 7% 2	1869
	11th to 20th	Day	63% 5% 9% 13% 10% 1	1904
	21st to end	Day	65% 3 8% 13% 10% 2	1730
March	1st to 10th	Day	66% 5% 6% 9% 11% 2	4579
	11th to 20th	Day	59% 5% 13% 11% 11% 1	4902
	21st to end	Day	55% 4 7% 16% 17% 2	6025
April	1st to 10th	Day	59% 4 8% 16% 11% 2	2520
	11th to 20th	Day	56% 5% 8% 19% 11% 2	2494
	21st to end	Day	57% 5% 7% 16% 11% 3	2700
May	1st to 10th	Day	60% 5% 7% 19% 8% 1	8249
	11th to 20th	Day	53% 6% 14% 19% 7% 1	8225
	21st to end	Day	54% 4 9% 19% 12% 1	9061
June	1st to 10th	Day	55% 7% 10% 17% 10% 1	2940
	11th to 20th	Day	50% 7% 11% 20% 10% 2	2940
	21st to end	Day	56% 7% 11% 18% 8%	2940
July	1st to 10th	Day	48% 4 14% 23% 10%	8210
	11th to 20th	Day	40% 5% 16% 30% 8%	8205
	21st to end	Day	43% 5% 17% 29% 7%	8795
August	1st to 10th	Day	53% 5% 15% 19% 7% 1	6469
	11th to 20th	Day	46% 6% 17% 24% 6%	5992
	21st to end	Day	46% 5% 17% 21% 10% 1	6080
September	1st to 10th	Day	43% 6% 14% 25% 11%	2520
	11th to 20th	Day	39% 6% 13% 30% 11% 1	2469
	21st to end	Day	46% 6% 12% 23% 12%	2310
October	1st to 10th	Day	53% 3 10% 27% 7%	3367
	11th to 20th	Day	55% 5% 11% 22% 6% 1	3243
	21st to end	Day	57% 4 19% 13% 7% 1	3180
November	1st to 10th	Day	57% 6% 12% 18% 7% 1	1851
	11th to 20th	Day	66% 5% 10% 11% 8% 1	1727
	21st to end	Day	71% 6% 9% 10% 4 1	1680
December	1st to 10th	Day	77% 4 7% 10% 3	2680
	11th to 20th	Day	71% 4 6% 14% 6%	3066
	21st to end	Day	66% 4 7% 15% 8%	4048
January	1st to 10th	Night	71% 4 8% 13% 3 1	8234
	11th to 20th	Night	76% 4 6% 9% 4 1	8280
	21st to end	Night	68% 4 6% 10% 11% 1	9057
February	1st to 10th	Night	63% 5% 9% 16% 6% 1	2749
	11th to 20th	Night	63% 4 9% 15% 8% 1	2612
	21st to end	Night	60% 5% 10% 15% 9% 1	2076
March	1st to 10th	Night	63% 5% 8% 10% 11% 2	5494
	11th to 20th	Night	56% 5% 12% 15% 9% 3	5263
	21st to end	Night	58% 4 7% 19% 10% 3	5148
April	1st to 10th	Night	57% 4 9% 17% 12% 2	2100
	11th to 20th	Night	49% 5% 11% 20% 13% 2	2075
	21st to end	Night	52% 4 9% 19% 13% 2	1936
May	1st to 10th	Night	55% 7% 11% 19% 7% 1	4666
	11th to 20th	Night	50% 7% 13% 20% 9% 1	4640
	21st to end	Night	55% 5% 9% 19% 12% 1	5115
June	1st to 10th	Night	49% 8% 11% 21% 11% 1	1680
	11th to 20th	Night	46% 7% 12% 21% 12% 3	1680
	21st to end	Night	49% 7% 12% 20% 11% 1	1680
July	1st to 10th	Night	47% 5% 16% 21% 10%	4640
	11th to 20th	Night	41% 4 18% 30% 7%	4632
	21st to end	Night	42% 6% 17% 28% 8%	4967
August	1st to 10th	Night	48% 6% 15% 23% 8% 1	3656
	11th to 20th	Night	47% 4 18% 25% 6%	4070
	21st to end	Night	46% 5% 15% 23% 10% 1	5045
September	1st to 10th	Night	39% 6% 15% 27% 12% 1	2100
	11th to 20th	Night	37% 5% 15% 32% 10% 1	2150
	21st to end	Night	42% 6% 13% 27% 13%	2310
October	1st to 10th	Night	47% 4 14% 23% 11%	4029
	11th to 20th	Night	53% 4 13% 21% 8%	3963
	21st to end	Night	55% 4 16% 15% 9% 1	4610
November	1st to 10th	Night	58% 6% 13% 18% 5% 1	2667
	11th to 20th	Night	62% 5% 11% 14% 7% 1	2889
	21st to end	Night	70% 5% 10% 11% 4	2940
December	1st to 10th	Night	75% 4 11% 8% 3	4720
	11th to 20th	Night	70% 4 5% 13% 8%	5348
	21st to end	Night	67% 3 5% 11% 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% 25% 37% 14% 3	220
	11th to 20th	Day	30% 20% 33% 11% 5%	220
	21st to end	Day	22% 24% 33% 16% 4 1	242
February	1st to 10th	Day	29% 32% 28% 9% 2	319
	11th to 20th	Day	29% 29% 32% 9% 1	382
	21st to end	Day	31% 22% 33% 12% 2	446
March	1st to 10th	Day	29% 21% 33% 13% 3 1	540
	11th to 20th	Day	30% 23% 31% 13% 2 1	540
	21st to end	Day	33% 22% 25% 14% 4 1	594
April	1st to 10th	Day	33% 22% 28% 13% 4 1	540
	11th to 20th	Day	37% 18% 22% 13% 8% 2	532
	21st to end	Day	33% 20% 30% 11% 4 1	540
May	1st to 10th	Day	30% 21% 30% 12% 5% 1	543
	11th to 20th	Day	26% 19% 30% 19% 5% 1	567
	21st to end	Day	28% 21% 28% 18% 5% 1	617
June	1st to 10th	Day	29% 17% 31% 17% 5% 1	570
	11th to 20th	Day	24% 19% 29% 19% 8% 1	570
	21st to end	Day	26% 15% 34% 16% 7% 1	570
July	1st to 10th	Day	19% 13% 35% 25% 7% 2	565
	11th to 20th	Day	18% 14% 36% 25% 6% 1	564
	21st to end	Day	17% 13% 35% 25% 8% 2	620
August	1st to 10th	Day	18% 10% 30% 29% 10% 2	566
	11th to 20th	Day	18% 8% 31% 25% 13% 6%	559
	21st to end	Day	21% 16% 27% 19% 12% 5%	627
September	1st to 10th	Day	22% 12% 30% 19% 12% 5%	570
	11th to 20th	Day	16% 13% 24% 24% 15% 8%	570
	21st to end	Day	24% 15% 24% 21% 11% 6%	570
October	1st to 10th	Day	30% 17% 21% 19% 10% 2	570
	11th to 20th	Day	32% 22% 24% 15% 6% 1	534
	21st to end	Day	36% 15% 27% 18% 4	462
November	1st to 10th	Day	37% 16% 25% 17% 4 1	425
	11th to 20th	Day	30% 25% 25% 13% 7%	267
	21st to end	Day	34% 27% 27% 11% 1	220
December	1st to 10th	Day	34% 19% 28% 15% 4	220
	11th to 20th	Day	32% 28% 30% 8% 2	220
	21st to end	Day	31% 25% 27% 12% 3 2	242
January	1st to 10th	Night	26% 19% 36% 16% 3	840
	11th to 20th	Night	28% 20% 29% 18% 5%	840
	21st to end	Night	17% 18% 36% 22% 6% 1	924
February	1st to 10th	Night	18% 22% 34% 20% 5% 1	840
	11th to 20th	Night	23% 22% 34% 18% 3	823
	21st to end	Night	23% 19% 32% 22% 3	692
March	1st to 10th	Night	26% 19% 32% 20% 3	840
	11th to 20th	Night	26% 21% 30% 19% 3 1	840
	21st to end	Night	27% 16% 30% 22% 6% 1	924
April	1st to 10th	Night	31% 17% 27% 21% 4	840
	11th to 20th	Night	28% 16% 28% 22% 6%	831
	21st to end	Night	27% 16% 30% 19% 8%	676
May	1st to 10th	Night	23% 13% 29% 25% 8% 2	420
	11th to 20th	Night	24% 9% 29% 29% 8%	414
	21st to end	Night	20% 11% 36% 25% 7%	455
June	1st to 10th	Night	22% 8% 31% 31% 8%	420
	11th to 20th	Night	23% 9% 26% 30% 12% 1	420
	21st to end	Night	23% 5% 21% 36% 15%	420
July	1st to 10th	Night	16% 6% 23% 43% 12%	410
	11th to 20th	Night	15% 6% 23% 39% 17%	408
	21st to end	Night	12% 6% 27% 36% 17% 1	460
August	1st to 10th	Night	16% 4 18% 43% 18%	418
	11th to 20th	Night	15% 6% 19% 35% 25% 1	598
	21st to end	Night	19% 8% 23% 31% 16% 2	924
September	1st to 10th	Night	20% 7% 25% 34% 13% 1	840
	11th to 20th	Night	19% 7% 20% 32% 21% 2	840
	21st to end	Night	21% 10% 24% 26% 18% 2	840
October	1st to 10th	Night	25% 11% 25% 25% 13% 1	840
	11th to 20th	Night	31% 12% 26% 23% 8%	813
	21st to end	Night	32% 14% 25% 23% 6%	880
November	1st to 10th	Night	29% 16% 27% 21% 6% 1	820
	11th to 20th	Night	26% 19% 29% 17% 8% 1	840
	21st to end	Night	32% 20% 25% 17% 5% 1	840
December	1st to 10th	Night	30% 20% 28% 17% 6%	840
	11th to 20th	Night	30% 22% 28% 15% 5% 1	840
	21st to end	Night	35% 18% 26% 17% 4	924

Page generated at 2026-10-11 05:06:30. Version ac07

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