Le Domaine
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Le Domaine clear sky chart from 2005-11-06 to 2026-08-15.

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% 12% 4 10% 6% 5% 5% 4 5% 6% 26%	144816
	Night	15% 14% 5% 11% 6% 5% 5% 4 5% 5% 25%	137016
Transparency	Day	58% 3 9% 20% 9% 1	148284
	Night	61% 2 9% 18% 9% 1	141625
Seeing	Day	26% 15% 32% 18% 7% 2	16809
	Night	26% 12% 30% 23% 8% 1	25505

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% 16% 7% 20% 11% 7% 6% 4 4 4 9%	4661
	11th to 20th	Day	8% 20% 10% 20% 9% 5% 3 3 4 5% 13%	4650
	21st to end	Day	7% 13% 8% 19% 8% 6% 6% 6% 6% 6% 16%	5282
February	1st to 10th	Day	8% 19% 7% 15% 9% 7% 4 4 5% 6% 17%	1890
	11th to 20th	Day	10% 18% 7% 16% 7% 5% 4 3 5% 5% 20%	1843
	21st to end	Day	16% 18% 6% 11% 6% 6% 5% 4 4 5% 21%	1669
March	1st to 10th	Day	18% 19% 4 11% 5% 4 4 3 4 4 22%	4656
	11th to 20th	Day	14% 15% 5% 14% 7% 5% 5% 3 3 5% 24%	5090
	21st to end	Day	14% 14% 5% 10% 5% 5% 4 3 4 4 31%	5838
April	1st to 10th	Day	21% 16% 4 9% 4 4 3 2 3 4 29%	2520
	11th to 20th	Day	22% 14% 4 8% 4 3 3 3 4 6% 30%	2494
	21st to end	Day	19% 13% 4 9% 4 4 4 3 4 5% 31%	2777
May	1st to 10th	Day	18% 13% 4 9% 5% 5% 6% 4 6% 6% 24%	8237
	11th to 20th	Day	17% 11% 4 9% 5% 6% 5% 5% 6% 7% 27%	8221
	21st to end	Day	19% 10% 4 8% 5% 5% 5% 3 5% 6% 31%	9060
June	1st to 10th	Day	21% 9% 3 8% 6% 5% 5% 4 6% 6% 26%	2940
	11th to 20th	Day	14% 8% 3 7% 6% 6% 5% 5% 7% 7% 33%	2965
	21st to end	Day	18% 7% 3 9% 6% 6% 5% 4 6% 7% 28%	3150
July	1st to 10th	Day	15% 7% 3 7% 5% 5% 5% 4 7% 9% 33%	8465
	11th to 20th	Day	12% 6% 2 6% 5% 5% 5% 5% 7% 10% 38%	8280
	21st to end	Day	13% 8% 3 7% 5% 5% 5% 4 7% 9% 34%	8993
August	1st to 10th	Day	15% 7% 3 9% 6% 6% 6% 5% 6% 7% 30%	4670
	11th to 20th	Day	17% 8% 3 6% 5% 5% 6% 4 7% 7% 33%	4226
	21st to end	Day	13% 7% 3 7% 5% 5% 6% 4 6% 9% 35%	4378
September	1st to 10th	Day	19% 7% 2 8% 5% 3 5% 3 4 7% 37%	2400
	11th to 20th	Day	17% 8% 2 6% 4 4 4 3 5% 7% 40%	2400
	21st to end	Day	20% 11% 3 6% 4 3 4 3 5% 6% 34%	2115
October	1st to 10th	Day	20% 13% 4 7% 4 4 3 3 5% 8% 31%	2000
	11th to 20th	Day	25% 17% 5% 9% 4 4 4 3 4 4 21%	2000
	21st to end	Day	27% 19% 4 9% 4 5% 4 3 4 5% 18%	2039
November	1st to 10th	Day	17% 19% 6% 11% 3 4 3 3 3 5% 25%	1753
	11th to 20th	Day	17% 19% 8% 15% 8% 4 4 3 3 4 16%	1680
	21st to end	Day	23% 22% 9% 15% 6% 4 3 3 3 4 9%	1680
December	1st to 10th	Day	16% 25% 9% 16% 6% 6% 3 3 3 4 8%	2680
	11th to 20th	Day	15% 20% 6% 14% 11% 6% 5% 3 2 3 14%	3066
	21st to end	Day	16% 20% 9% 13% 9% 4 4 3 3 4 14%	4048
January	1st to 10th	Night	10% 19% 9% 18% 9% 6% 5% 4 4 4 12%	8234
	11th to 20th	Night	10% 19% 8% 19% 10% 7% 5% 4 5% 3 11%	8235
	21st to end	Night	5% 13% 9% 18% 9% 8% 8% 4 7% 5% 15%	8895
February	1st to 10th	Night	10% 14% 5% 13% 9% 8% 5% 4 5% 5% 20%	2730
	11th to 20th	Night	11% 17% 6% 13% 8% 7% 5% 4 5% 5% 20%	2663
	21st to end	Night	11% 17% 6% 12% 8% 6% 6% 3 5% 5% 22%	2136
March	1st to 10th	Night	17% 20% 5% 10% 6% 4 4 3 4 4 23%	5401
	11th to 20th	Night	12% 16% 5% 13% 7% 6% 5% 4 5% 6% 22%	5089
	21st to end	Night	15% 13% 4 11% 6% 6% 5% 4 5% 5% 27%	5322
April	1st to 10th	Night	20% 13% 5% 10% 5% 4 4 2 4 5% 28%	2100
	11th to 20th	Night	16% 12% 4 7% 4 4 4 3 5% 5% 35%	2075
	21st to end	Night	22% 10% 4 8% 4 4 4 3 4 5% 32%	1859
May	1st to 10th	Night	17% 12% 3 8% 5% 4 5% 4 5% 8% 29%	4660
	11th to 20th	Night	17% 9% 3 8% 5% 4 4 3 5% 6% 35%	4639
	21st to end	Night	17% 11% 4 8% 5% 5% 4 3 5% 6% 33%	5114
June	1st to 10th	Night	17% 9% 3 7% 5% 6% 5% 4 6% 6% 31%	1680
	11th to 20th	Night	16% 8% 3 7% 5% 4 4 4 5% 7% 36%	1645
	21st to end	Night	18% 8% 2 6% 5% 4 4 5% 5% 7% 36%	1470
July	1st to 10th	Night	13% 9% 3 8% 6% 5% 5% 5% 6% 9% 32%	4469
	11th to 20th	Night	13% 7% 2 6% 4 5% 5% 4 6% 8% 39%	4680
	21st to end	Night	15% 8% 3 7% 5% 4 4 3 5% 7% 40%	5084
August	1st to 10th	Night	10% 9% 2 7% 4 4 5% 4 6% 8% 40%	2696
	11th to 20th	Night	18% 8% 3 7% 4 4 4 4 5% 6% 37%	2911
	21st to end	Night	16% 6% 3 7% 4 5% 5% 4 7% 8% 35%	3487
September	1st to 10th	Night	14% 8% 3 5% 5% 4 4 3 5% 8% 42%	2000
	11th to 20th	Night	17% 8% 2 5% 3 4 4 4 5% 5% 43%	2000
	21st to end	Night	19% 9% 3 6% 4 4 3 3 5% 6% 38%	2282
October	1st to 10th	Night	20% 10% 3 7% 4 4 4 3 4 6% 35%	2400
	11th to 20th	Night	23% 16% 4 9% 4 4 3 3 4 5% 25%	2400
	21st to end	Night	24% 18% 5% 9% 4 4 3 3 4 5% 21%	2800
November	1st to 10th	Night	18% 18% 5% 9% 5% 4 4 3 4 5% 24%	2762
	11th to 20th	Night	18% 17% 7% 13% 6% 6% 3 3 4 4 18%	2940
	21st to end	Night	22% 21% 8% 13% 7% 4 3 2 3 3 12%	2940
December	1st to 10th	Night	16% 20% 8% 18% 10% 7% 4 3 3 3 8%	4720
	11th to 20th	Night	20% 19% 5% 13% 7% 5% 4 3 4 4 17%	5348
	21st to end	Night	17% 22% 7% 14% 8% 4 4 3 2 4 14%	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	80% 1 6% 8% 4	4662
	11th to 20th	Day	76% 1 3 11% 8%	4680
	21st to end	Day	67% 2 5% 14% 11%	5282
February	1st to 10th	Day	69% 2 6% 14% 8% 1	1890
	11th to 20th	Day	67% 1 8% 13% 10% 1	1852
	21st to end	Day	66% 2 5% 15% 11%	1669
March	1st to 10th	Day	67% 1 5% 12% 12% 2	4659
	11th to 20th	Day	65% 2 9% 13% 9% 1	5090
	21st to end	Day	58% 1 4 18% 16% 2	5838
April	1st to 10th	Day	61% 1 7% 16% 12% 2	2520
	11th to 20th	Day	57% 2 6% 22% 12% 2	2494
	21st to end	Day	57% 2 6% 17% 15% 2	2777
May	1st to 10th	Day	59% 3 6% 20% 10% 3	8249
	11th to 20th	Day	56% 4 9% 23% 8%	8225
	21st to end	Day	55% 2 8% 19% 15% 1	9061
June	1st to 10th	Day	58% 3 7% 20% 12% 1	2940
	11th to 20th	Day	48% 4 11% 24% 12% 2	2965
	21st to end	Day	55% 4 11% 21% 9%	3150
July	1st to 10th	Day	46% 5% 13% 26% 10%	8396
	11th to 20th	Day	40% 5% 16% 29% 8% 1	8205
	21st to end	Day	45% 6% 15% 27% 8%	8795
August	1st to 10th	Day	51% 5% 12% 26% 6%	4656
	11th to 20th	Day	48% 4 15% 26% 7%	4265
	21st to end	Day	45% 4 11% 28% 11% 1	4378
September	1st to 10th	Day	47% 3 13% 25% 12% 1	2400
	11th to 20th	Day	45% 3 15% 27% 10% 1	2400
	21st to end	Day	52% 3 12% 23% 9%	2115
October	1st to 10th	Day	56% 3 9% 25% 6%	3260
	11th to 20th	Day	59% 2 13% 18% 7% 1	3240
	21st to end	Day	68% 3 13% 12% 4 1	3264
November	1st to 10th	Day	63% 3 10% 17% 7%	1753
	11th to 20th	Day	73% 2 8% 11% 6%	1680
	21st to end	Day	80% 2 6% 7% 4	1680
December	1st to 10th	Day	81% 2 5% 10% 2	2680
	11th to 20th	Day	77% 2 3 13% 5%	3066
	21st to end	Day	75% 2 5% 15% 4	4048
January	1st to 10th	Night	78% 1 8% 10% 3	8234
	11th to 20th	Night	79% 1 5% 9% 5% 1	8280
	21st to end	Night	69% 2 4 14% 10%	8895
February	1st to 10th	Night	65% 2 7% 17% 8% 1	2730
	11th to 20th	Night	67% 2 6% 15% 9% 1	2665
	21st to end	Night	65% 2 7% 16% 9% 1	2136
March	1st to 10th	Night	66% 1 7% 11% 12% 3	5411
	11th to 20th	Night	64% 3 11% 13% 7% 1	5090
	21st to end	Night	60% 2 5% 19% 12% 2	5322
April	1st to 10th	Night	61% 1 6% 17% 13% 2	2100
	11th to 20th	Night	52% 2 6% 23% 15% 2	2075
	21st to end	Night	55% 2 6% 20% 15% 2	1859
May	1st to 10th	Night	54% 3 8% 22% 11% 3	4666
	11th to 20th	Night	51% 3 11% 22% 11% 1	4640
	21st to end	Night	53% 3 9% 21% 13% 1	5115
June	1st to 10th	Night	52% 3 9% 24% 12% 1	1680
	11th to 20th	Night	48% 3 10% 23% 14% 2	1645
	21st to end	Night	48% 4 12% 26% 10% 1	1470
July	1st to 10th	Night	48% 6% 12% 21% 11% 1	4429
	11th to 20th	Night	42% 5% 17% 27% 9%	4632
	21st to end	Night	45% 4 14% 27% 10%	4967
August	1st to 10th	Night	41% 5% 19% 27% 8%	2686
	11th to 20th	Night	46% 4 16% 27% 8%	2938
	21st to end	Night	46% 4 15% 25% 9% 2	3487
September	1st to 10th	Night	42% 3 17% 27% 10%	2000
	11th to 20th	Night	42% 3 16% 30% 9%	2000
	21st to end	Night	48% 3 12% 27% 9%	2282
October	1st to 10th	Night	51% 2 11% 23% 13%	3920
	11th to 20th	Night	59% 3 11% 21% 6% 1	3899
	21st to end	Night	61% 2 15% 13% 9% 1	4512
November	1st to 10th	Night	64% 2 11% 17% 6%	2762
	11th to 20th	Night	69% 2 9% 13% 6%	2940
	21st to end	Night	78% 2 7% 10% 3	2940
December	1st to 10th	Night	82% 3 5% 7% 3	4720
	11th to 20th	Night	72% 2 4 14% 7%	5348
	21st to end	Night	76% 1 3 12% 7%	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	21% 19% 46% 12% 1 1	220
	11th to 20th	Day	25% 17% 38% 15% 5% 2	220
	21st to end	Day	19% 21% 38% 18% 4	271
February	1st to 10th	Day	28% 23% 36% 8% 4 1	330
	11th to 20th	Day	27% 27% 34% 11% 1	330
	21st to end	Day	31% 19% 37% 11% 1	385
March	1st to 10th	Day	28% 19% 35% 14% 3	540
	11th to 20th	Day	31% 19% 32% 14% 4	540
	21st to end	Day	31% 18% 35% 12% 4 1	594
April	1st to 10th	Day	36% 19% 25% 14% 5% 1	540
	11th to 20th	Day	37% 15% 24% 14% 8% 2	532
	21st to end	Day	30% 20% 32% 14% 4 1	540
May	1st to 10th	Day	30% 15% 33% 15% 6% 1	543
	11th to 20th	Day	28% 15% 29% 20% 7% 2	567
	21st to end	Day	26% 18% 31% 17% 7% 1	617
June	1st to 10th	Day	27% 11% 35% 20% 6% 1	570
	11th to 20th	Day	23% 16% 33% 18% 9% 2	595
	21st to end	Day	22% 13% 31% 24% 9% 1	780
July	1st to 10th	Day	17% 10% 37% 27% 9% 1	634
	11th to 20th	Day	19% 11% 37% 22% 9% 2	564
	21st to end	Day	18% 10% 30% 30% 10% 2	620
August	1st to 10th	Day	19% 8% 31% 29% 9% 3	566
	11th to 20th	Day	18% 7% 30% 27% 13% 6%	535
	21st to end	Day	19% 11% 32% 21% 12% 5%	583
September	1st to 10th	Day	25% 8% 32% 20% 12% 3	530
	11th to 20th	Day	20% 8% 26% 24% 16% 6%	530
	21st to end	Day	25% 13% 26% 19% 14% 3	530
October	1st to 10th	Day	26% 14% 28% 20% 9% 2	530
	11th to 20th	Day	31% 18% 31% 14% 4 1	530
	21st to end	Day	38% 12% 29% 17% 3 1	494
November	1st to 10th	Day	35% 15% 34% 12% 4 1	327
	11th to 20th	Day	28% 22% 32% 15% 3 1	220
	21st to end	Day	33% 24% 32% 8% 2 1	220
December	1st to 10th	Day	33% 15% 32% 15% 4 1	220
	11th to 20th	Day	32% 20% 35% 9% 3 1	220
	21st to end	Day	30% 19% 37% 10% 3 1	242
January	1st to 10th	Night	30% 15% 33% 18% 3	840
	11th to 20th	Night	30% 15% 30% 20% 5% 1	840
	21st to end	Night	18% 13% 36% 25% 7% 1	924
February	1st to 10th	Night	19% 17% 37% 21% 5%	840
	11th to 20th	Night	23% 17% 36% 20% 3	823
	21st to end	Night	25% 17% 31% 23% 4	692
March	1st to 10th	Night	25% 18% 32% 21% 4	840
	11th to 20th	Night	27% 18% 31% 18% 5% 1	840
	21st to end	Night	25% 15% 32% 21% 6%	924
April	1st to 10th	Night	30% 13% 29% 23% 5%	840
	11th to 20th	Night	27% 15% 28% 21% 9%	831
	21st to end	Night	28% 10% 31% 23% 8% 1	599
May	1st to 10th	Night	23% 8% 30% 28% 10% 1	420
	11th to 20th	Night	26% 9% 27% 28% 8% 1	414
	21st to end	Night	22% 11% 34% 26% 7%	455
June	1st to 10th	Night	23% 7% 32% 28% 9%	420
	11th to 20th	Night	21% 9% 28% 29% 12%	420
	21st to end	Night	21% 6% 29% 33% 11%	420
July	1st to 10th	Night	16% 6% 32% 39% 8%	410
	11th to 20th	Night	16% 8% 26% 36% 13%	408
	21st to end	Night	17% 5% 27% 37% 14%	460
August	1st to 10th	Night	14% 5% 26% 37% 18% 1	435
	11th to 20th	Night	17% 3 23% 33% 21% 3	606
	21st to end	Night	20% 5% 29% 27% 16% 3	820
September	1st to 10th	Night	21% 5% 30% 28% 13% 2	800
	11th to 20th	Night	23% 6% 26% 26% 19% 2	800
	21st to end	Night	25% 7% 26% 27% 14% 1	800
October	1st to 10th	Night	25% 10% 31% 23% 10% 1	800
	11th to 20th	Night	33% 11% 28% 20% 6% 2	800
	21st to end	Night	34% 12% 28% 21% 4 1	880
November	1st to 10th	Night	31% 14% 31% 18% 5% 1	820
	11th to 20th	Night	31% 16% 30% 15% 7% 1	840
	21st to end	Night	36% 18% 24% 18% 4 1	840
December	1st to 10th	Night	33% 16% 30% 17% 5% 1	840
	11th to 20th	Night	31% 15% 30% 18% 5% 1	840
	21st to end	Night	34% 15% 27% 19% 4 1	924

Page generated at 2026-08-12 03:37:14. Version ac07

Copyright © 2026 Attilla Danko.