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 2024-03-06.

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	19% 12% 4 8% 7% 3 5% 4 5% 6% 27%	78323
	Night	18% 13% 5% 8% 7% 3 4 4 4 6% 27%	81192
Transparency	Day	57% 6% 11% 17% 9% 1	78028
	Night	57% 6% 11% 17% 8% 1	81021
Seeing	Day	26% 19% 29% 18% 7% 2	13519
	Night	25% 15% 28% 23% 9% 1	22697

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	16% 19% 7% 17% 10% 4 4 3 2 3 15%	2517
	11th to 20th	Day	13% 16% 6% 18% 13% 3 2 2 3 4 19%	2520
	21st to end	Day	11% 16% 9% 11% 9% 4 6% 5% 5% 5% 18%	2772
February	1st to 10th	Day	11% 19% 6% 12% 10% 4 5% 3 3 6% 21%	1691
	11th to 20th	Day	12% 18% 6% 13% 7% 4 5% 3 4 5% 23%	1709
	21st to end	Day	16% 18% 6% 9% 7% 4 5% 3 5% 4 22%	1570
March	1st to 10th	Day	15% 14% 6% 10% 7% 4 5% 4 4 6% 26%	1847
	11th to 20th	Day	16% 14% 5% 9% 7% 4 5% 4 3 7% 26%	1908
	21st to end	Day	19% 10% 4 7% 6% 3 4 4 5% 5% 32%	2343
April	1st to 10th	Day	21% 15% 6% 7% 6% 2 4 3 4 6% 27%	2160
	11th to 20th	Day	23% 10% 5% 5% 6% 3 3 4 4 5% 32%	2134
	21st to end	Day	21% 12% 4 7% 6% 3 4 5% 4 5% 30%	2313
May	1st to 10th	Day	22% 11% 4 7% 5% 3 5% 4 4 6% 30%	2520
	11th to 20th	Day	20% 9% 3 7% 6% 3 4 4 5% 5% 34%	2478
	21st to end	Day	20% 9% 3 6% 5% 3 5% 4 5% 7% 33%	2725
June	1st to 10th	Day	24% 9% 3 6% 5% 4 5% 5% 6% 7% 26%	2520
	11th to 20th	Day	18% 7% 3 7% 6% 4 6% 6% 5% 8% 32%	2520
	21st to end	Day	24% 8% 3 6% 6% 4 5% 6% 6% 6% 27%	2520
July	1st to 10th	Day	17% 6% 3 5% 5% 3 5% 5% 6% 8% 35%	2520
	11th to 20th	Day	16% 7% 3 5% 6% 4 6% 6% 7% 8% 32%	2520
	21st to end	Day	15% 7% 4 6% 6% 3 6% 6% 6% 8% 31%	2744
August	1st to 10th	Day	17% 8% 3 7% 7% 4 5% 7% 6% 8% 29%	2506
	11th to 20th	Day	16% 7% 2 7% 5% 4 6% 6% 6% 8% 34%	2305
	21st to end	Day	17% 6% 2 6% 6% 3 6% 5% 5% 8% 36%	2376
September	1st to 10th	Day	19% 6% 2 5% 6% 3 4 5% 5% 6% 39%	2160
	11th to 20th	Day	18% 7% 3 5% 4 3 4 5% 6% 7% 38%	2117
	21st to end	Day	22% 7% 3 5% 4 3 3 4 5% 7% 37%	1980
October	1st to 10th	Day	25% 10% 2 5% 5% 3 4 4 4 7% 30%	1807
	11th to 20th	Day	29% 12% 4 7% 7% 2 4 4 4 5% 22%	1787
	21st to end	Day	28% 15% 4 6% 5% 3 4 4 4 5% 22%	1782
November	1st to 10th	Day	18% 14% 4 7% 5% 2 4 5% 5% 6% 29%	1671
	11th to 20th	Day	21% 16% 7% 9% 7% 4 4 5% 4 4 19%	1563
	21st to end	Day	22% 16% 6% 10% 8% 3 4 4 2 4 20%	1520
December	1st to 10th	Day	23% 20% 7% 9% 7% 3 3 4 4 5% 15%	1520
	11th to 20th	Day	21% 17% 7% 12% 8% 3 4 4 4 4 16%	1906
	21st to end	Day	21% 20% 6% 11% 6% 2 4 4 3 5% 18%	2772
January	1st to 10th	Night	15% 20% 9% 11% 7% 3 4 4 4 4 19%	4429
	11th to 20th	Night	12% 15% 7% 14% 15% 4 3 4 5% 5% 16%	4440
	21st to end	Night	10% 16% 10% 15% 9% 5% 6% 4 5% 5% 16%	4884
February	1st to 10th	Night	13% 17% 7% 10% 8% 4 6% 5% 4 6% 21%	2488
	11th to 20th	Night	13% 16% 7% 12% 9% 4 5% 4 4 5% 23%	2356
	21st to end	Night	14% 16% 7% 9% 6% 4 5% 5% 5% 6% 25%	1884
March	1st to 10th	Night	17% 13% 5% 9% 7% 4 6% 4 4 5% 25%	2217
	11th to 20th	Night	18% 15% 5% 8% 7% 3 4 4 4 5% 28%	2050
	21st to end	Night	16% 11% 3 7% 6% 3 5% 4 5% 5% 36%	2012
April	1st to 10th	Night	24% 12% 4 6% 6% 3 3 4 4 6% 29%	1800
	11th to 20th	Night	20% 9% 3 5% 5% 2 3 5% 5% 6% 36%	1775
	21st to end	Night	20% 11% 4 7% 5% 3 4 4 4 6% 33%	1660
May	1st to 10th	Night	20% 9% 4 6% 5% 3 4 5% 4 6% 35%	1440
	11th to 20th	Night	20% 7% 4 5% 5% 3 5% 3 3 7% 38%	1415
	21st to end	Night	17% 7% 3 5% 6% 3 4 4 5% 7% 38%	1550
June	1st to 10th	Night	19% 7% 4 6% 6% 3 5% 5% 6% 8% 31%	1440
	11th to 20th	Night	18% 7% 2 5% 5% 3 5% 5% 6% 8% 36%	1440
	21st to end	Night	19% 8% 3 5% 4 3 6% 5% 6% 5% 36%	1440
July	1st to 10th	Night	14% 5% 4 6% 4 3 6% 4 5% 8% 42%	1440
	11th to 20th	Night	15% 5% 3 4 5% 4 5% 5% 7% 8% 41%	1440
	21st to end	Night	13% 5% 3 5% 5% 3 5% 5% 7% 10% 39%	1574
August	1st to 10th	Night	13% 7% 3 4 6% 3 5% 5% 6% 9% 39%	1432
	11th to 20th	Night	14% 6% 3 6% 6% 3 4 5% 6% 7% 42%	1575
	21st to end	Night	17% 6% 3 5% 4 3 4 4 6% 8% 40%	1980
September	1st to 10th	Night	17% 8% 2 4 4 2 5% 4 5% 7% 42%	1800
	11th to 20th	Night	18% 6% 2 4 4 2 3 5% 5% 7% 44%	1842
	21st to end	Night	19% 6% 3 5% 3 2 4 4 4 9% 41%	1980
October	1st to 10th	Night	21% 8% 3 6% 6% 3 4 4 5% 5% 36%	2150
	11th to 20th	Night	25% 13% 3 7% 5% 2 5% 4 4 5% 28%	2173
	21st to end	Night	27% 13% 4 7% 6% 3 4 4 4 5% 23%	2574
November	1st to 10th	Night	21% 13% 5% 7% 5% 3 4 4 5% 6% 27%	2407
	11th to 20th	Night	19% 16% 6% 9% 7% 4 4 4 4 6% 21%	2613
	21st to end	Night	22% 18% 6% 10% 6% 3 5% 4 4 4 18%	2660
December	1st to 10th	Night	20% 20% 8% 13% 6% 3 4 4 4 4 14%	2660
	11th to 20th	Night	22% 17% 6% 9% 8% 3 4 3 3 4 20%	3288
	21st to end	Night	22% 22% 5% 10% 8% 3 3 3 3 3 17%	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	73% 5% 8% 10% 4	2518
	11th to 20th	Day	71% 3 5% 14% 6% 1	2520
	21st to end	Day	66% 7% 9% 11% 6% 1	2772
February	1st to 10th	Day	65% 4 7% 16% 6% 2	1691
	11th to 20th	Day	63% 6% 10% 11% 9% 1	1718
	21st to end	Day	65% 3 8% 13% 9% 2	1570
March	1st to 10th	Day	60% 5% 8% 16% 9% 2	1850
	11th to 20th	Day	58% 6% 9% 13% 11% 2	1908
	21st to end	Day	53% 4 9% 17% 12% 3	2343
April	1st to 10th	Day	59% 4 9% 16% 10% 2	2160
	11th to 20th	Day	54% 4 8% 19% 11% 2	2134
	21st to end	Day	57% 6% 8% 15% 11% 3	2313
May	1st to 10th	Day	55% 5% 8% 18% 12% 2	2520
	11th to 20th	Day	52% 5% 9% 17% 14% 2	2482
	21st to end	Day	51% 6% 11% 18% 12% 2	2725
June	1st to 10th	Day	56% 7% 11% 16% 10% 1	2520
	11th to 20th	Day	49% 8% 11% 20% 10% 3	2520
	21st to end	Day	57% 8% 10% 16% 8%	2520
July	1st to 10th	Day	43% 8% 16% 24% 9%	2450
	11th to 20th	Day	45% 9% 14% 23% 9%	2445
	21st to end	Day	48% 9% 15% 20% 8%	2591
August	1st to 10th	Day	49% 10% 16% 21% 4	2492
	11th to 20th	Day	45% 9% 17% 21% 7%	2305
	21st to end	Day	45% 8% 14% 22% 11% 1	2376
September	1st to 10th	Day	44% 6% 14% 24% 12%	2160
	11th to 20th	Day	43% 7% 13% 27% 10% 1	2117
	21st to end	Day	46% 7% 13% 24% 9%	1980
October	1st to 10th	Day	54% 5% 11% 20% 9% 1	1807
	11th to 20th	Day	64% 6% 10% 16% 4 1	1787
	21st to end	Day	64% 5% 11% 13% 6% 1	1782
November	1st to 10th	Day	54% 6% 13% 19% 7% 1	1671
	11th to 20th	Day	66% 6% 10% 11% 7% 1	1563
	21st to end	Day	68% 6% 10% 11% 4 1	1520
December	1st to 10th	Day	72% 6% 8% 9% 5%	1520
	11th to 20th	Day	69% 5% 9% 12% 5%	1906
	21st to end	Day	70% 5% 6% 12% 7%	2772
January	1st to 10th	Night	67% 6% 13% 11% 3	4429
	11th to 20th	Night	67% 6% 10% 11% 4 1	4440
	21st to end	Night	69% 6% 9% 8% 7% 1	4884
February	1st to 10th	Night	63% 5% 10% 15% 6% 1	2488
	11th to 20th	Night	63% 5% 9% 15% 8% 1	2358
	21st to end	Night	59% 5% 11% 15% 9% 2	1884
March	1st to 10th	Night	59% 6% 8% 16% 8% 2	2227
	11th to 20th	Night	57% 5% 11% 14% 12% 1	2051
	21st to end	Night	50% 5% 9% 19% 14% 4	2012
April	1st to 10th	Night	56% 4 9% 17% 12% 2	1800
	11th to 20th	Night	47% 6% 11% 21% 13% 2	1775
	21st to end	Night	52% 5% 10% 18% 12% 3	1660
May	1st to 10th	Night	50% 6% 9% 19% 13% 3	1440
	11th to 20th	Night	46% 7% 10% 18% 16% 3	1416
	21st to end	Night	45% 7% 12% 21% 13% 2	1551
June	1st to 10th	Night	49% 9% 12% 21% 9%	1440
	11th to 20th	Night	45% 8% 11% 22% 12% 3	1440
	21st to end	Night	48% 8% 12% 20% 11%	1440
July	1st to 10th	Night	38% 9% 16% 26% 12% 1	1400
	11th to 20th	Night	39% 9% 16% 26% 9% 1	1392
	21st to end	Night	38% 10% 19% 24% 9%	1486
August	1st to 10th	Night	38% 11% 18% 25% 7%	1422
	11th to 20th	Night	40% 8% 18% 25% 10%	1575
	21st to end	Night	41% 8% 17% 25% 9%	1980
September	1st to 10th	Night	40% 6% 15% 25% 13% 1	1800
	11th to 20th	Night	39% 6% 15% 31% 9% 1	1842
	21st to end	Night	41% 7% 14% 28% 10%	1980
October	1st to 10th	Night	49% 7% 10% 22% 11% 1	2150
	11th to 20th	Night	57% 6% 12% 18% 6%	2173
	21st to end	Night	61% 6% 11% 14% 6% 1	2574
November	1st to 10th	Night	56% 6% 14% 18% 6% 1	2407
	11th to 20th	Night	62% 5% 11% 14% 6% 1	2613
	21st to end	Night	69% 5% 10% 11% 5%	2660
December	1st to 10th	Night	73% 5% 9% 9% 4	2660
	11th to 20th	Night	68% 4 8% 14% 6% 1	3288
	21st to end	Night	72% 4 6% 12% 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% 27% 35% 14% 3	180
	11th to 20th	Day	28% 21% 32% 13% 6% 1	180
	21st to end	Day	22% 25% 33% 15% 4 1	198
February	1st to 10th	Day	32% 33% 26% 7% 2	261
	11th to 20th	Day	28% 32% 32% 8%	316
	21st to end	Day	32% 24% 29% 13% 2	382
March	1st to 10th	Day	27% 22% 34% 15% 3	440
	11th to 20th	Day	30% 22% 30% 15% 3 1	420
	21st to end	Day	32% 20% 25% 16% 5% 1	462
April	1st to 10th	Day	31% 19% 30% 15% 4 1	420
	11th to 20th	Day	35% 17% 23% 14% 9% 2	412
	21st to end	Day	30% 21% 30% 13% 4 1	420
May	1st to 10th	Day	30% 20% 31% 13% 5% 1	423
	11th to 20th	Day	25% 21% 30% 18% 5% 1	447
	21st to end	Day	25% 20% 32% 17% 5% 1	485
June	1st to 10th	Day	30% 18% 31% 16% 6%	450
	11th to 20th	Day	21% 20% 29% 19% 9% 1	450
	21st to end	Day	26% 15% 32% 19% 7% 1	450
July	1st to 10th	Day	17% 12% 35% 26% 8% 2	445
	11th to 20th	Day	16% 12% 37% 27% 6% 1	444
	21st to end	Day	16% 11% 36% 27% 7% 2	488
August	1st to 10th	Day	18% 12% 29% 29% 11% 2	446
	11th to 20th	Day	17% 8% 30% 25% 13% 7%	439
	21st to end	Day	21% 17% 27% 18% 12% 6%	495
September	1st to 10th	Day	21% 12% 30% 19% 12% 6%	450
	11th to 20th	Day	18% 14% 27% 21% 14% 7%	450
	21st to end	Day	23% 17% 23% 21% 10% 6%	450
October	1st to 10th	Day	31% 19% 19% 18% 11% 2	450
	11th to 20th	Day	33% 23% 22% 15% 6% 1	444
	21st to end	Day	38% 15% 26% 17% 4	396
November	1st to 10th	Day	35% 16% 25% 19% 5% 1	365
	11th to 20th	Day	31% 25% 26% 11% 7%	223
	21st to end	Day	31% 28% 27% 12% 1	180
December	1st to 10th	Day	36% 19% 28% 13% 4	180
	11th to 20th	Day	31% 30% 29% 8% 2 1	180
	21st to end	Day	34% 26% 25% 10% 3 2	198
January	1st to 10th	Night	27% 20% 35% 15% 4	760
	11th to 20th	Night	28% 20% 29% 18% 5%	760
	21st to end	Night	18% 17% 37% 22% 6% 1	836
February	1st to 10th	Night	19% 22% 35% 19% 4 1	760
	11th to 20th	Night	22% 23% 34% 18% 3	743
	21st to end	Night	23% 20% 31% 22% 3	628
March	1st to 10th	Night	26% 19% 32% 21% 3	743
	11th to 20th	Night	26% 21% 29% 19% 4 1	720
	21st to end	Night	25% 15% 30% 23% 7% 1	792
April	1st to 10th	Night	30% 17% 26% 23% 5%	720
	11th to 20th	Night	27% 16% 27% 23% 6% 1	711
	21st to end	Night	26% 17% 28% 20% 8%	580
May	1st to 10th	Night	23% 13% 29% 25% 9% 2	360
	11th to 20th	Night	24% 10% 29% 29% 8%	354
	21st to end	Night	19% 11% 38% 25% 7% 1	389
June	1st to 10th	Night	23% 8% 31% 30% 7%	360
	11th to 20th	Night	21% 8% 27% 30% 13% 1	360
	21st to end	Night	21% 6% 20% 36% 16% 1	360
July	1st to 10th	Night	15% 7% 24% 40% 14% 1	350
	11th to 20th	Night	15% 5% 24% 38% 18% 1	348
	21st to end	Night	12% 7% 28% 36% 16% 1	394
August	1st to 10th	Night	16% 4 19% 41% 19% 1	358
	11th to 20th	Night	14% 6% 19% 34% 25% 2	511
	21st to end	Night	18% 9% 25% 30% 17% 2	792
September	1st to 10th	Night	20% 7% 26% 32% 14% 1	720
	11th to 20th	Night	21% 8% 20% 32% 19% 1	720
	21st to end	Night	21% 11% 24% 25% 18% 2	720
October	1st to 10th	Night	24% 12% 26% 24% 13% 1	720
	11th to 20th	Night	32% 12% 25% 22% 8% 1	720
	21st to end	Night	32% 15% 25% 22% 6%	792
November	1st to 10th	Night	28% 16% 27% 21% 6% 1	740
	11th to 20th	Night	26% 19% 29% 16% 8% 1	760
	21st to end	Night	32% 20% 25% 17% 5% 1	760
December	1st to 10th	Night	31% 20% 26% 17% 5%	760
	11th to 20th	Night	30% 21% 28% 15% 5% 1	760
	21st to end	Night	35% 18% 27% 16% 4	836

Page generated at 2024-03-03 06:28:58. Version ac07

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