La Seigneurie du Triton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the La Seigneurie du Triton clear sky chart from 2005-11-06 to 2026-09-29.

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 10% 6% 5% 5% 4 5% 6% 24%	149407
	Night	17% 14% 5% 11% 7% 5% 5% 3 4 5% 23%	142013
Transparency	Day	59% 7% 11% 16% 7% 1	152840
	Night	63% 6% 10% 15% 6%	146670
Seeing	Day	27% 18% 30% 17% 6% 2	17526
	Night	26% 14% 30% 22% 7% 1	25977

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	10% 19% 9% 21% 8% 6% 6% 4 3 4 11%	4661
	11th to 20th	Day	9% 18% 8% 21% 12% 7% 5% 3 4 3 9%	4650
	21st to end	Day	5% 10% 6% 19% 8% 7% 7% 6% 7% 6% 19%	5124
February	1st to 10th	Day	8% 16% 5% 15% 12% 8% 7% 3 4 4 17%	1692
	11th to 20th	Day	13% 19% 6% 15% 7% 7% 5% 4 5% 4 16%	1976
	21st to end	Day	12% 16% 6% 13% 8% 6% 5% 4 4 4 21%	1730
March	1st to 10th	Day	15% 20% 7% 12% 6% 4 4 3 4 4 22%	4576
	11th to 20th	Day	15% 17% 6% 13% 5% 5% 4 3 4 5% 22%	4759
	21st to end	Day	15% 18% 5% 10% 4 4 4 3 3 5% 29%	6072
April	1st to 10th	Day	22% 16% 5% 10% 5% 4 4 2 4 5% 23%	2520
	11th to 20th	Day	21% 13% 4 9% 4 4 4 3 4 5% 30%	2567
	21st to end	Day	21% 14% 4 10% 4 4 4 3 4 6% 26%	2730
May	1st to 10th	Day	25% 13% 4 8% 5% 5% 5% 3 5% 6% 22%	8093
	11th to 20th	Day	23% 9% 3 7% 5% 5% 5% 4 6% 7% 26%	8221
	21st to end	Day	21% 10% 4 8% 5% 5% 4 4 6% 6% 26%	9096
June	1st to 10th	Day	22% 9% 3 7% 6% 5% 5% 4 6% 7% 26%	3150
	11th to 20th	Day	22% 8% 3 6% 5% 5% 4 5% 5% 8% 29%	3150
	21st to end	Day	25% 9% 3 8% 6% 6% 5% 4 6% 6% 24%	3150
July	1st to 10th	Day	19% 7% 3 8% 5% 4 5% 4 7% 8% 29%	8347
	11th to 20th	Day	18% 7% 3 8% 5% 5% 5% 4 6% 8% 31%	8280
	21st to end	Day	17% 7% 3 7% 5% 5% 6% 5% 7% 9% 30%	8993
August	1st to 10th	Day	20% 7% 3 7% 5% 5% 5% 5% 7% 9% 28%	6483
	11th to 20th	Day	21% 10% 3 7% 5% 5% 5% 5% 7% 9% 23%	6074
	21st to end	Day	19% 8% 3 8% 5% 5% 4 4 6% 8% 31%	6223
September	1st to 10th	Day	20% 8% 3 7% 4 4 5% 3 5% 7% 32%	2520
	11th to 20th	Day	20% 8% 3 6% 3 4 3 4 6% 7% 36%	2378
	21st to end	Day	25% 9% 3 6% 4 4 4 3 5% 6% 32%	2288
October	1st to 10th	Day	25% 11% 3 8% 4 3 4 3 4 5% 29%	2131
	11th to 20th	Day	24% 20% 5% 9% 5% 4 3 3 5% 4 19%	1860
	21st to end	Day	28% 20% 4 8% 4 3 3 2 4 4 20%	1980
November	1st to 10th	Day	22% 21% 6% 10% 4 4 4 3 3 5% 20%	1851
	11th to 20th	Day	21% 23% 7% 12% 4 3 3 2 3 4 17%	1801
	21st to end	Day	19% 25% 8% 15% 6% 4 3 2 3 5% 11%	1532
December	1st to 10th	Day	17% 18% 8% 17% 12% 6% 4 3 3 3 9%	2350
	11th to 20th	Day	18% 18% 6% 16% 10% 5% 5% 3 3 5% 12%	2688
	21st to end	Day	18% 20% 6% 11% 8% 6% 6% 3 4 5% 13%	3711
January	1st to 10th	Night	12% 20% 9% 18% 8% 8% 7% 4 4 3 9%	8234
	11th to 20th	Night	9% 22% 8% 21% 13% 6% 4 2 3 2 9%	8235
	21st to end	Night	5% 9% 7% 17% 10% 10% 8% 6% 6% 5% 17%	9057
February	1st to 10th	Night	9% 15% 6% 13% 9% 7% 7% 5% 5% 4 21%	2924
	11th to 20th	Night	11% 20% 7% 14% 8% 6% 5% 4 5% 4 17%	2530
	21st to end	Night	10% 18% 6% 12% 7% 6% 5% 3 4 5% 22%	2076
March	1st to 10th	Night	18% 17% 5% 13% 7% 5% 5% 3 4 5% 19%	5484
	11th to 20th	Night	13% 16% 5% 12% 7% 6% 6% 3 5% 6% 20%	5419
	21st to end	Night	15% 17% 5% 10% 5% 5% 4 3 6% 6% 26%	5087
April	1st to 10th	Night	21% 18% 5% 10% 5% 4 3 3 4 4 24%	2100
	11th to 20th	Night	22% 13% 3 8% 4 4 3 3 4 6% 29%	2000
	21st to end	Night	21% 13% 4 8% 4 4 3 3 5% 6% 30%	1890
May	1st to 10th	Night	23% 10% 3 8% 5% 5% 5% 4 4 5% 29%	4849
	11th to 20th	Night	26% 9% 3 6% 5% 4 4 4 5% 7% 29%	4639
	21st to end	Night	21% 9% 4 8% 5% 5% 4 4 5% 6% 30%	5062
June	1st to 10th	Night	21% 10% 4 7% 5% 4 5% 3 5% 7% 29%	1470
	11th to 20th	Night	20% 8% 2 7% 6% 4 4 4 5% 7% 33%	1470
	21st to end	Night	22% 9% 4 7% 5% 5% 4 3 6% 8% 28%	1470
July	1st to 10th	Night	18% 7% 2 9% 6% 5% 5% 4 6% 8% 29%	4598
	11th to 20th	Night	19% 7% 3 7% 5% 4 5% 4 6% 8% 32%	4680
	21st to end	Night	19% 7% 2 7% 4 4 4 4 6% 7% 37%	5084
August	1st to 10th	Night	20% 8% 2 7% 5% 5% 5% 3 6% 7% 32%	3666
	11th to 20th	Night	20% 8% 3 8% 5% 5% 5% 4 6% 7% 28%	3925
	21st to end	Night	21% 9% 3 7% 5% 4 4 4 4 6% 33%	4900
September	1st to 10th	Night	21% 7% 2 5% 4 4 3 2 5% 6% 40%	2100
	11th to 20th	Night	19% 9% 3 7% 4 5% 3 3 5% 6% 37%	2242
	21st to end	Night	20% 9% 3 7% 4 4 4 3 4 5% 38%	2289
October	1st to 10th	Night	20% 12% 3 7% 4 3 3 3 4 6% 35%	2265
	11th to 20th	Night	26% 14% 3 8% 5% 3 4 3 4 5% 24%	2540
	21st to end	Night	26% 19% 4 7% 4 3 4 3 4 5% 20%	2860
November	1st to 10th	Night	22% 19% 6% 8% 5% 4 4 3 4 5% 21%	2667
	11th to 20th	Night	20% 18% 6% 12% 5% 4 5% 3 4 4 18%	2817
	21st to end	Night	21% 22% 7% 15% 7% 4 3 2 3 3 12%	3086
December	1st to 10th	Night	13% 18% 8% 21% 10% 6% 4 3 3 4 10%	5060
	11th to 20th	Night	21% 18% 6% 13% 9% 6% 3 3 3 3 14%	5741
	21st to end	Night	18% 21% 6% 13% 6% 5% 4 2 2 4 17%	7497

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	79% 4 6% 10% 2	4662
	11th to 20th	Day	80% 4 5% 7% 5%	4680
	21st to end	Day	62% 5% 6% 15% 11%	5124
February	1st to 10th	Day	70% 5% 6% 11% 6% 2	1692
	11th to 20th	Day	70% 5% 7% 10% 8% 1	1985
	21st to end	Day	65% 4 8% 15% 6% 2	1730
March	1st to 10th	Day	67% 5% 6% 10% 10% 3	4579
	11th to 20th	Day	65% 5% 10% 11% 8% 1	4759
	21st to end	Day	59% 4 5% 14% 15% 3	6072
April	1st to 10th	Day	65% 4 10% 11% 8% 2	2520
	11th to 20th	Day	57% 5% 8% 17% 11% 2	2567
	21st to end	Day	59% 5% 9% 14% 11% 2	2730
May	1st to 10th	Day	60% 7% 9% 14% 9% 1	8105
	11th to 20th	Day	55% 9% 12% 16% 7% 1	8225
	21st to end	Day	56% 7% 9% 14% 11% 3	9097
June	1st to 10th	Day	56% 8% 9% 18% 8% 2	3150
	11th to 20th	Day	52% 8% 12% 17% 9% 2	3150
	21st to end	Day	60% 8% 10% 13% 9%	3150
July	1st to 10th	Day	50% 7% 13% 22% 8%	8277
	11th to 20th	Day	49% 7% 16% 23% 4	8205
	21st to end	Day	50% 8% 16% 21% 5%	8795
August	1st to 10th	Day	51% 8% 16% 20% 5%	6469
	11th to 20th	Day	54% 10% 17% 16% 3	6115
	21st to end	Day	50% 8% 16% 18% 8%	6223
September	1st to 10th	Day	50% 7% 16% 20% 7%	2520
	11th to 20th	Day	47% 7% 18% 21% 7%	2378
	21st to end	Day	53% 7% 13% 17% 10%	2288
October	1st to 10th	Day	56% 7% 11% 21% 4	3469
	11th to 20th	Day	66% 5% 11% 16% 2	3011
	21st to end	Day	62% 7% 15% 13% 2	3180
November	1st to 10th	Day	68% 6% 9% 12% 4	1851
	11th to 20th	Day	73% 5% 7% 10% 4 1	1801
	21st to end	Day	79% 6% 7% 6% 1	1532
December	1st to 10th	Day	81% 5% 5% 8% 2	2350
	11th to 20th	Day	76% 4 6% 11% 3	2688
	21st to end	Day	73% 5% 6% 11% 5%	3711
January	1st to 10th	Night	80% 5% 7% 8% 1	8234
	11th to 20th	Night	83% 3 4 6% 3	8280
	21st to end	Night	65% 6% 7% 13% 9%	9057
February	1st to 10th	Night	64% 6% 8% 14% 7% 1	2924
	11th to 20th	Night	70% 5% 8% 11% 6% 1	2532
	21st to end	Night	65% 3 8% 14% 9% 1	2076
March	1st to 10th	Night	69% 5% 6% 11% 9% 1	5494
	11th to 20th	Night	64% 6% 12% 12% 6%	5420
	21st to end	Night	58% 5% 7% 19% 9% 2	5087
April	1st to 10th	Night	65% 5% 8% 12% 9% 2	2100
	11th to 20th	Night	56% 5% 9% 18% 10% 1	2000
	21st to end	Night	55% 6% 9% 19% 10% 1	1890
May	1st to 10th	Night	55% 8% 9% 19% 9% 1	4855
	11th to 20th	Night	53% 8% 12% 20% 6%	4640
	21st to end	Night	53% 7% 11% 15% 12% 3	5063
June	1st to 10th	Night	54% 8% 9% 20% 7% 1	1470
	11th to 20th	Night	49% 9% 13% 16% 10% 2	1470
	21st to end	Night	53% 8% 13% 16% 9%	1470
July	1st to 10th	Night	51% 8% 15% 18% 8%	4558
	11th to 20th	Night	48% 8% 20% 20% 4	4632
	21st to end	Night	46% 7% 19% 23% 5%	4967
August	1st to 10th	Night	50% 8% 18% 17% 6%	3656
	11th to 20th	Night	52% 10% 19% 17% 2	3950
	21st to end	Night	51% 8% 13% 22% 7%	4900
September	1st to 10th	Night	46% 7% 14% 23% 9%	2100
	11th to 20th	Night	48% 7% 16% 24% 5%	2242
	21st to end	Night	48% 7% 12% 24% 8%	2289
October	1st to 10th	Night	54% 6% 14% 21% 5% 1	3707
	11th to 20th	Night	60% 5% 14% 18% 2	4128
	21st to end	Night	62% 6% 13% 12% 6%	4610
November	1st to 10th	Night	66% 6% 11% 12% 3 1	2667
	11th to 20th	Night	69% 6% 9% 11% 4	2817
	21st to end	Night	78% 6% 6% 8% 2	3086
December	1st to 10th	Night	80% 5% 7% 7% 2	5060
	11th to 20th	Night	76% 4 5% 12% 3	5742
	21st to end	Night	73% 4 6% 11% 6%	7497

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	24% 20% 42% 11% 3	220
	11th to 20th	Day	23% 19% 39% 13% 6%	220
	21st to end	Day	18% 18% 36% 20% 7% 1	242
February	1st to 10th	Day	19% 25% 42% 11% 1 2	227
	11th to 20th	Day	22% 29% 33% 14% 2	464
	21st to end	Day	24% 26% 33% 12% 4	446
March	1st to 10th	Day	27% 20% 33% 15% 5%	540
	11th to 20th	Day	29% 18% 33% 14% 5%	540
	21st to end	Day	28% 26% 27% 14% 4 1	594
April	1st to 10th	Day	34% 20% 29% 12% 5% 1	540
	11th to 20th	Day	33% 21% 26% 12% 6% 2	532
	21st to end	Day	31% 22% 30% 12% 4 1	540
May	1st to 10th	Day	32% 21% 27% 12% 7% 1	543
	11th to 20th	Day	27% 18% 30% 19% 6% 1	567
	21st to end	Day	30% 22% 29% 15% 3 1	627
June	1st to 10th	Day	26% 16% 31% 20% 7% 1	780
	11th to 20th	Day	27% 16% 28% 20% 8% 1	780
	21st to end	Day	28% 13% 30% 20% 8% 1	780
July	1st to 10th	Day	22% 16% 31% 23% 6% 1	593
	11th to 20th	Day	20% 15% 36% 20% 7% 2	564
	21st to end	Day	24% 13% 29% 24% 9% 1	620
August	1st to 10th	Day	22% 11% 32% 23% 8% 3	566
	11th to 20th	Day	21% 7% 31% 27% 11% 3	559
	21st to end	Day	25% 16% 28% 15% 11% 6%	627
September	1st to 10th	Day	26% 16% 29% 19% 7% 4	570
	11th to 20th	Day	21% 15% 27% 22% 12% 4	570
	21st to end	Day	24% 18% 25% 17% 12% 5%	562
October	1st to 10th	Day	26% 18% 28% 19% 7% 3	530
	11th to 20th	Day	37% 17% 25% 10% 9% 2	453
	21st to end	Day	39% 16% 27% 14% 4	462
November	1st to 10th	Day	35% 21% 29% 11% 3	425
	11th to 20th	Day	31% 19% 31% 13% 4 1	341
	21st to end	Day	33% 23% 30% 13% 1	220
December	1st to 10th	Day	34% 15% 29% 19% 3	220
	11th to 20th	Day	29% 25% 36% 6% 3 1	220
	21st to end	Day	31% 19% 31% 12% 5% 2	242
January	1st to 10th	Night	25% 17% 34% 18% 5%	840
	11th to 20th	Night	25% 19% 31% 19% 6%	840
	21st to end	Night	15% 15% 36% 25% 8% 1	924
February	1st to 10th	Night	16% 20% 36% 21% 7%	840
	11th to 20th	Night	24% 17% 38% 17% 5%	823
	21st to end	Night	24% 16% 35% 21% 4	692
March	1st to 10th	Night	23% 17% 33% 22% 4	840
	11th to 20th	Night	27% 19% 30% 18% 5% 1	840
	21st to end	Night	23% 19% 32% 19% 6% 1	924
April	1st to 10th	Night	32% 15% 29% 20% 4	840
	11th to 20th	Night	30% 15% 27% 20% 6% 1	756
	21st to end	Night	30% 18% 30% 18% 4	630
May	1st to 10th	Night	28% 13% 29% 24% 5%	492
	11th to 20th	Night	25% 10% 33% 25% 6%	414
	21st to end	Night	28% 13% 32% 22% 5%	455
June	1st to 10th	Night	24% 9% 34% 27% 5% 1	420
	11th to 20th	Night	25% 9% 28% 30% 9%	420
	21st to end	Night	24% 10% 28% 30% 9%	420
July	1st to 10th	Night	20% 7% 32% 31% 9%	410
	11th to 20th	Night	17% 10% 27% 33% 12%	408
	21st to end	Night	20% 6% 27% 36% 10% 1	460
August	1st to 10th	Night	18% 7% 25% 37% 12%	418
	11th to 20th	Night	21% 8% 25% 31% 15% 1	543
	21st to end	Night	26% 10% 24% 24% 14% 2	854
September	1st to 10th	Night	26% 8% 25% 32% 9% 1	840
	11th to 20th	Night	24% 8% 25% 28% 13% 1	840
	21st to end	Night	25% 12% 26% 23% 12% 1	833
October	1st to 10th	Night	26% 12% 27% 27% 7% 1	800
	11th to 20th	Night	36% 12% 26% 18% 8%	800
	21st to end	Night	39% 13% 27% 17% 4	880
November	1st to 10th	Night	34% 15% 29% 18% 4 1	820
	11th to 20th	Night	30% 18% 27% 17% 8% 1	840
	21st to end	Night	34% 18% 28% 16% 4	917
December	1st to 10th	Night	30% 15% 29% 19% 6% 1	950
	11th to 20th	Night	28% 17% 31% 19% 5% 1	950
	21st to end	Night	30% 18% 29% 19% 4 1	1004

Page generated at 2026-09-26 04:18:45. Version ac07

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