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 2025-05-26.

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% 13% 5% 11% 6% 5% 5% 4 5% 6% 23%	113506
	Night	17% 15% 5% 12% 7% 5% 5% 3 4 5% 22%	115789
Transparency	Day	61% 7% 11% 14% 7% 1	116985
	Night	63% 6% 10% 14% 6%	120475
Seeing	Day	28% 18% 30% 17% 6% 2	15707
	Night	27% 14% 30% 22% 7% 1	24383

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% 23% 10% 21% 8% 6% 5% 3 3 2 7%	3597
	11th to 20th	Day	9% 15% 7% 22% 14% 7% 4 3 4 4 10%	3570
	21st to end	Day	6% 12% 7% 19% 6% 6% 7% 5% 5% 5% 22%	3960
February	1st to 10th	Day	8% 16% 6% 16% 12% 8% 7% 3 4 4 16%	1611
	11th to 20th	Day	13% 20% 6% 15% 7% 7% 5% 4 5% 4 15%	1879
	21st to end	Day	12% 16% 6% 13% 7% 6% 5% 4 4 4 21%	1650
March	1st to 10th	Day	15% 20% 7% 12% 6% 4 4 3 3 4 22%	4476
	11th to 20th	Day	15% 17% 5% 13% 5% 5% 5% 3 4 5% 22%	4656
	21st to end	Day	15% 18% 5% 10% 4 4 4 3 3 5% 29%	5941
April	1st to 10th	Day	22% 16% 5% 10% 5% 4 3 2 3 5% 24%	2400
	11th to 20th	Day	20% 13% 4 9% 4 3 4 3 4 5% 30%	2443
	21st to end	Day	22% 14% 4 10% 4 4 4 2 4 6% 26%	2600
May	1st to 10th	Day	22% 11% 4 8% 5% 5% 5% 3 5% 6% 25%	4490
	11th to 20th	Day	17% 9% 4 8% 5% 5% 5% 4 6% 8% 30%	4538
	21st to end	Day	20% 8% 3 8% 6% 5% 5% 4 6% 7% 28%	4929
June	1st to 10th	Day	22% 10% 3 8% 6% 5% 5% 4 5% 7% 25%	2850
	11th to 20th	Day	21% 8% 3 6% 5% 5% 4 5% 5% 8% 29%	2850
	21st to end	Day	26% 9% 3 8% 6% 6% 5% 4 5% 6% 24%	2850
July	1st to 10th	Day	19% 8% 3 9% 6% 4 5% 4 7% 8% 26%	4479
	11th to 20th	Day	19% 8% 3 9% 7% 5% 5% 4 6% 7% 26%	4440
	21st to end	Day	16% 7% 2 7% 5% 5% 6% 5% 7% 8% 31%	4814
August	1st to 10th	Day	19% 8% 3 8% 5% 6% 5% 5% 7% 10% 25%	4423
	11th to 20th	Day	22% 9% 3 8% 5% 5% 5% 5% 7% 8% 23%	4121
	21st to end	Day	22% 8% 3 8% 5% 5% 4 4 4 6% 30%	4281
September	1st to 10th	Day	21% 8% 3 7% 4 4 5% 3 6% 7% 32%	2280
	11th to 20th	Day	20% 8% 3 7% 3 4 3 3 6% 7% 36%	2152
	21st to end	Day	27% 9% 3 6% 4 4 4 3 5% 6% 30%	2090
October	1st to 10th	Day	26% 11% 3 8% 4 3 4 3 4 5% 28%	2025
	11th to 20th	Day	25% 21% 5% 9% 4 4 3 3 5% 4 18%	1767
	21st to end	Day	29% 19% 4 8% 4 3 3 2 4 4 20%	1881
November	1st to 10th	Day	22% 20% 5% 10% 3 4 4 3 3 5% 21%	1761
	11th to 20th	Day	21% 22% 6% 12% 4 4 4 2 3 4 18%	1715
	21st to end	Day	19% 24% 8% 14% 6% 4 3 3 3 5% 11%	1459
December	1st to 10th	Day	17% 18% 8% 18% 12% 5% 4 3 3 3 9%	2280
	11th to 20th	Day	19% 18% 6% 16% 9% 5% 5% 3 3 5% 12%	2618
	21st to end	Day	18% 20% 6% 11% 8% 6% 6% 3 4 5% 13%	3630
January	1st to 10th	Night	13% 23% 10% 19% 8% 8% 6% 3 3 2 7%	6349
	11th to 20th	Night	9% 17% 7% 22% 15% 8% 4 2 3 3 10%	6315
	21st to end	Night	6% 11% 7% 15% 9% 9% 8% 5% 6% 5% 19%	6996
February	1st to 10th	Night	10% 16% 6% 12% 9% 7% 7% 5% 5% 5% 20%	2785
	11th to 20th	Night	11% 20% 7% 14% 8% 6% 5% 4 4 4 17%	2407
	21st to end	Night	11% 19% 6% 12% 7% 6% 6% 3 4 5% 21%	1980
March	1st to 10th	Night	18% 17% 5% 13% 7% 5% 5% 3 4 5% 18%	5364
	11th to 20th	Night	13% 16% 5% 12% 7% 6% 6% 4 5% 7% 21%	5302
	21st to end	Night	15% 17% 4 10% 5% 5% 4 3 6% 6% 26%	4976
April	1st to 10th	Night	21% 18% 5% 9% 5% 4 3 3 4 4 24%	2000
	11th to 20th	Night	22% 13% 3 7% 4 4 3 4 4 6% 29%	1904
	21st to end	Night	21% 14% 4 8% 4 4 3 3 4 5% 30%	1800
May	1st to 10th	Night	22% 10% 3 8% 5% 5% 4 4 4 5% 30%	2702
	11th to 20th	Night	19% 10% 3 6% 4 4 4 4 6% 8% 32%	2575
	21st to end	Night	22% 8% 3 7% 5% 5% 4 4 6% 7% 29%	2758
June	1st to 10th	Night	21% 10% 4 7% 5% 4 5% 3 5% 7% 29%	1330
	11th to 20th	Night	19% 8% 3 6% 6% 4 3 4 5% 7% 34%	1330
	21st to end	Night	23% 9% 4 7% 5% 5% 4 3 6% 7% 28%	1330
July	1st to 10th	Night	19% 8% 3 9% 6% 5% 5% 4 6% 7% 27%	2477
	11th to 20th	Night	18% 8% 3 8% 6% 4 5% 4 6% 8% 30%	2520
	21st to end	Night	14% 6% 2 5% 4 4 4 4 6% 8% 43%	2739
August	1st to 10th	Night	16% 8% 2 8% 5% 5% 6% 3 7% 8% 32%	2506
	11th to 20th	Night	20% 9% 3 8% 4 5% 4 4 6% 7% 29%	2675
	21st to end	Night	20% 8% 3 7% 5% 5% 5% 4 4 6% 33%	3373
September	1st to 10th	Night	22% 7% 2 5% 4 4 3 2 5% 5% 40%	1900
	11th to 20th	Night	20% 9% 3 7% 4 4 3 3 5% 6% 37%	2028
	21st to end	Night	21% 9% 3 7% 4 4 4 3 4 5% 36%	2090
October	1st to 10th	Night	21% 12% 3 7% 4 3 3 3 4 6% 33%	2152
	11th to 20th	Night	28% 15% 3 8% 5% 3 4 3 4 5% 23%	2413
	21st to end	Night	27% 18% 4 8% 4 4 4 3 4 5% 20%	2717
November	1st to 10th	Night	21% 19% 5% 8% 5% 4 4 3 4 5% 21%	2537
	11th to 20th	Night	20% 18% 5% 12% 5% 4 5% 3 4 4 19%	2683
	21st to end	Night	22% 22% 7% 14% 7% 4 3 3 3 3 12%	2939
December	1st to 10th	Night	14% 18% 8% 21% 10% 6% 4 3 3 4 10%	4910
	11th to 20th	Night	21% 18% 6% 13% 9% 6% 3 3 3 3 15%	5591
	21st to end	Night	18% 21% 6% 12% 6% 5% 4 2 2 4 17%	7336

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	84% 4 5% 6% 1	3598
	11th to 20th	Day	77% 4 6% 8% 4	3600
	21st to end	Day	62% 6% 5% 15% 12%	3960
February	1st to 10th	Day	72% 5% 6% 10% 6% 2	1611
	11th to 20th	Day	71% 5% 7% 9% 7% 1	1888
	21st to end	Day	66% 4 8% 14% 5% 2	1650
March	1st to 10th	Day	67% 5% 6% 10% 10% 3	4479
	11th to 20th	Day	65% 5% 10% 11% 8% 1	4656
	21st to end	Day	59% 4 5% 15% 15% 3	5941
April	1st to 10th	Day	65% 4 10% 11% 8% 2	2400
	11th to 20th	Day	56% 5% 8% 17% 12% 2	2443
	21st to end	Day	60% 5% 9% 13% 11% 2	2600
May	1st to 10th	Day	56% 9% 11% 13% 10% 2	4504
	11th to 20th	Day	48% 11% 15% 18% 7% 1	4542
	21st to end	Day	52% 8% 10% 15% 13% 2	4929
June	1st to 10th	Day	57% 8% 9% 16% 8% 2	2850
	11th to 20th	Day	51% 8% 13% 17% 9% 2	2850
	21st to end	Day	60% 8% 10% 13% 9%	2850
July	1st to 10th	Day	53% 8% 13% 23% 4	4409
	11th to 20th	Day	55% 8% 17% 16% 3	4365
	21st to end	Day	48% 9% 17% 21% 5%	4661
August	1st to 10th	Day	53% 9% 17% 17% 3	4409
	11th to 20th	Day	55% 10% 19% 13% 3	4162
	21st to end	Day	54% 8% 13% 15% 11%	4281
September	1st to 10th	Day	51% 7% 15% 19% 7%	2280
	11th to 20th	Day	48% 7% 18% 20% 7%	2152
	21st to end	Day	56% 7% 13% 17% 7%	2090
October	1st to 10th	Day	57% 7% 11% 20% 4	3363
	11th to 20th	Day	67% 5% 11% 15% 1	2918
	21st to end	Day	61% 7% 16% 13% 2	3081
November	1st to 10th	Day	67% 6% 9% 13% 4	1761
	11th to 20th	Day	72% 5% 8% 11% 4 1	1715
	21st to end	Day	78% 6% 8% 7% 1	1459
December	1st to 10th	Day	81% 5% 5% 8% 1	2280
	11th to 20th	Day	76% 4 6% 12% 3	2618
	21st to end	Day	73% 5% 6% 11% 5%	3630
January	1st to 10th	Night	84% 5% 6% 4 1	6349
	11th to 20th	Night	81% 4 5% 7% 3 1	6360
	21st to end	Night	63% 6% 8% 13% 9%	6996
February	1st to 10th	Night	65% 6% 8% 13% 7% 1	2785
	11th to 20th	Night	71% 5% 8% 10% 6% 1	2409
	21st to end	Night	66% 4 8% 14% 8% 1	1980
March	1st to 10th	Night	69% 5% 6% 11% 9% 1	5374
	11th to 20th	Night	63% 6% 12% 12% 6% 1	5303
	21st to end	Night	58% 5% 7% 19% 9% 2	4976
April	1st to 10th	Night	64% 5% 8% 12% 9% 2	2000
	11th to 20th	Night	56% 6% 9% 18% 11% 1	1904
	21st to end	Night	56% 6% 9% 18% 10% 1	1800
May	1st to 10th	Night	53% 9% 10% 18% 9% 1	2708
	11th to 20th	Night	45% 10% 16% 20% 7%	2576
	21st to end	Night	51% 9% 12% 17% 11% 1	2759
June	1st to 10th	Night	54% 8% 10% 19% 6% 2	1330
	11th to 20th	Night	47% 9% 13% 17% 11% 2	1330
	21st to end	Night	54% 9% 13% 15% 10%	1330
July	1st to 10th	Night	54% 8% 15% 19% 4	2437
	11th to 20th	Night	50% 9% 20% 17% 4	2472
	21st to end	Night	38% 9% 23% 22% 8%	2651
August	1st to 10th	Night	49% 9% 18% 18% 6%	2496
	11th to 20th	Night	53% 10% 20% 14% 3	2700
	21st to end	Night	50% 8% 13% 22% 7%	3373
September	1st to 10th	Night	46% 8% 13% 24% 9%	1900
	11th to 20th	Night	49% 7% 16% 22% 5%	2028
	21st to end	Night	50% 7% 13% 24% 6%	2090
October	1st to 10th	Night	55% 6% 14% 20% 5%	3594
	11th to 20th	Night	61% 5% 14% 18% 2	4001
	21st to end	Night	62% 6% 14% 12% 6% 1	4467
November	1st to 10th	Night	65% 7% 12% 13% 3 1	2537
	11th to 20th	Night	68% 6% 9% 11% 5%	2683
	21st to end	Night	78% 6% 6% 8% 2	2939
December	1st to 10th	Night	80% 5% 7% 6% 2	4910
	11th to 20th	Night	75% 4 5% 13% 3	5592
	21st to end	Night	72% 4 6% 12% 6%	7336

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	26% 22% 41% 11% 2	200
	11th to 20th	Day	22% 18% 39% 14% 7%	200
	21st to end	Day	20% 17% 36% 19% 7% 1	220
February	1st to 10th	Day	21% 27% 42% 9% 1 1	206
	11th to 20th	Day	23% 29% 33% 13% 2	427
	21st to end	Day	24% 27% 32% 12% 4	414
March	1st to 10th	Day	25% 19% 34% 16% 5%	500
	11th to 20th	Day	28% 19% 32% 14% 5%	500
	21st to end	Day	28% 25% 27% 14% 4 1	550
April	1st to 10th	Day	34% 20% 29% 12% 5% 1	500
	11th to 20th	Day	32% 22% 25% 12% 7% 2	492
	21st to end	Day	31% 21% 31% 12% 3 1	500
May	1st to 10th	Day	33% 20% 28% 12% 6% 1	503
	11th to 20th	Day	26% 18% 29% 19% 6% 1	527
	21st to end	Day	31% 21% 29% 15% 3 1	558
June	1st to 10th	Day	27% 16% 31% 19% 6% 1	680
	11th to 20th	Day	26% 17% 28% 20% 9% 1	680
	21st to end	Day	30% 11% 31% 20% 7% 1	680
July	1st to 10th	Day	21% 15% 33% 24% 6% 1	511
	11th to 20th	Day	20% 14% 34% 23% 7% 2	484
	21st to end	Day	24% 12% 29% 25% 10% 1	532
August	1st to 10th	Day	24% 12% 32% 22% 7% 3	486
	11th to 20th	Day	22% 7% 30% 27% 11% 3	479
	21st to end	Day	25% 16% 28% 15% 10% 6%	539
September	1st to 10th	Day	27% 15% 29% 19% 7% 4	490
	11th to 20th	Day	21% 14% 27% 22% 11% 4	490
	21st to end	Day	26% 17% 26% 16% 11% 4	490
October	1st to 10th	Day	27% 18% 25% 19% 7% 3	490
	11th to 20th	Day	39% 17% 25% 10% 8% 2	420
	21st to end	Day	39% 16% 28% 13% 4	429
November	1st to 10th	Day	35% 21% 28% 11% 4	395
	11th to 20th	Day	32% 20% 30% 14% 4 1	315
	21st to end	Day	33% 23% 31% 12% 2 1	200
December	1st to 10th	Day	35% 15% 28% 20% 4	200
	11th to 20th	Day	30% 24% 36% 6% 4 1	200
	21st to end	Day	32% 19% 30% 12% 5% 2	220
January	1st to 10th	Night	26% 18% 34% 17% 5%	800
	11th to 20th	Night	25% 19% 31% 19% 6%	800
	21st to end	Night	15% 15% 36% 26% 7% 1	880
February	1st to 10th	Night	17% 20% 37% 21% 5%	800
	11th to 20th	Night	24% 17% 38% 16% 5%	783
	21st to end	Night	24% 16% 35% 20% 5%	660
March	1st to 10th	Night	22% 17% 34% 22% 5%	800
	11th to 20th	Night	27% 18% 31% 19% 5% 1	800
	21st to end	Night	23% 20% 31% 19% 6% 1	880
April	1st to 10th	Night	31% 15% 29% 21% 4	800
	11th to 20th	Night	31% 14% 28% 20% 7% 1	720
	21st to end	Night	30% 18% 31% 18% 4	600
May	1st to 10th	Night	29% 13% 29% 23% 5%	469
	11th to 20th	Night	25% 10% 33% 25% 6%	394
	21st to end	Night	29% 13% 32% 20% 5%	423
June	1st to 10th	Night	25% 9% 34% 25% 5% 1	380
	11th to 20th	Night	23% 9% 29% 29% 9% 1	380
	21st to end	Night	24% 10% 28% 29% 8%	380
July	1st to 10th	Night	20% 8% 32% 30% 9% 1	370
	11th to 20th	Night	16% 10% 28% 32% 13% 1	368
	21st to end	Night	20% 6% 27% 36% 11% 1	416
August	1st to 10th	Night	19% 7% 26% 35% 13% 1	378
	11th to 20th	Night	21% 8% 26% 30% 15% 1	491
	21st to end	Night	25% 10% 26% 24% 14% 2	772
September	1st to 10th	Night	27% 7% 26% 31% 9% 1	760
	11th to 20th	Night	24% 8% 25% 28% 13% 2	760
	21st to end	Night	26% 13% 26% 23% 12% 1	760
October	1st to 10th	Night	27% 13% 26% 26% 8% 1	760
	11th to 20th	Night	37% 11% 26% 17% 8%	760
	21st to end	Night	39% 13% 27% 17% 4	836
November	1st to 10th	Night	34% 14% 28% 18% 4 1	780
	11th to 20th	Night	30% 17% 28% 17% 7% 1	800
	21st to end	Night	34% 18% 28% 16% 4	870
December	1st to 10th	Night	31% 15% 28% 19% 6% 1	900
	11th to 20th	Night	27% 17% 31% 19% 5% 1	900
	21st to end	Night	30% 18% 29% 18% 4 1	953

Page generated at 2025-05-23 09:20:57. Version ac07

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