Site d'observation de Lebel-sur-Quévillon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Site d'observation de Lebel-sur-Quévillon clear sky chart from 2005-11-06 to 2026-07-01.

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% 24%	138069
	Night	16% 15% 6% 12% 7% 6% 5% 4 5% 5% 21%	134357
Transparency	Day	61% 5% 10% 16% 7% 1	141525
	Night	66% 5% 9% 14% 6% 1	138991
Seeing	Day	26% 15% 31% 19% 7% 2	17097
	Night	26% 12% 30% 23% 8% 1	25879

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% 20% 9% 20% 8% 9% 7% 4 4 3 4	4094
	11th to 20th	Day	9% 17% 8% 20% 9% 4 7% 7% 7% 4 7%	4325
	21st to end	Day	5% 12% 7% 19% 8% 7% 8% 5% 8% 5% 14%	5164
February	1st to 10th	Day	7% 16% 6% 15% 9% 10% 6% 5% 6% 5% 15%	1890
	11th to 20th	Day	10% 20% 6% 14% 9% 6% 7% 5% 6% 5% 14%	1843
	21st to end	Day	11% 17% 6% 14% 9% 6% 6% 3 5% 5% 18%	1613
March	1st to 10th	Day	20% 17% 5% 12% 6% 4 5% 3 4 4 20%	4687
	11th to 20th	Day	19% 14% 5% 15% 8% 4 4 2 3 4 21%	5090
	21st to end	Day	12% 15% 7% 14% 6% 6% 5% 3 4 4 23%	5809
April	1st to 10th	Day	19% 18% 5% 12% 6% 4 3 2 3 5% 22%	2520
	11th to 20th	Day	19% 14% 5% 9% 4 4 4 3 4 5% 29%	2560
	21st to end	Day	20% 15% 3 8% 5% 4 4 3 4 4 28%	2819
May	1st to 10th	Day	15% 15% 6% 9% 5% 5% 5% 3 5% 5% 27%	8237
	11th to 20th	Day	16% 12% 3 9% 6% 5% 6% 4 6% 6% 26%	8221
	21st to end	Day	22% 10% 3 7% 4 4 4 3 5% 6% 32%	9060
June	1st to 10th	Day	24% 8% 3 7% 5% 5% 4 4 6% 7% 28%	3105
	11th to 20th	Day	15% 9% 3 7% 5% 4 5% 4 6% 8% 33%	3150
	21st to end	Day	21% 8% 3 6% 6% 4 5% 4 6% 7% 30%	3150
July	1st to 10th	Day	17% 7% 3 8% 6% 6% 6% 5% 7% 9% 26%	6820
	11th to 20th	Day	19% 7% 3 6% 5% 5% 5% 4 6% 8% 32%	6740
	21st to end	Day	18% 7% 3 7% 5% 5% 5% 4 6% 9% 31%	6926
August	1st to 10th	Day	19% 8% 3 7% 5% 6% 6% 5% 6% 9% 27%	4563
	11th to 20th	Day	21% 9% 3 7% 5% 5% 5% 4 5% 6% 31%	4188
	21st to end	Day	17% 8% 3 7% 5% 4 5% 3 5% 8% 35%	4477
September	1st to 10th	Day	24% 9% 2 7% 3 5% 4 4 5% 7% 30%	2400
	11th to 20th	Day	22% 10% 2 7% 4 5% 5% 3 7% 6% 28%	2400
	21st to end	Day	24% 10% 3 8% 5% 5% 3 3 4 5% 31%	2103
October	1st to 10th	Day	23% 12% 3 7% 5% 3 4 3 4 5% 30%	2000
	11th to 20th	Day	31% 20% 5% 9% 4 3 4 2 3 4 16%	2000
	21st to end	Day	29% 21% 6% 8% 4 3 3 3 4 3 15%	2027
November	1st to 10th	Day	22% 24% 6% 10% 5% 5% 3 3 4 4 16%	1661
	11th to 20th	Day	22% 24% 9% 13% 6% 4 3 2 3 4 11%	1680
	21st to end	Day	23% 28% 9% 15% 5% 3 3 2 2 2 7%	1680
December	1st to 10th	Day	11% 29% 10% 18% 8% 6% 4 2 3 3 7%	2680
	11th to 20th	Day	15% 21% 6% 15% 12% 5% 6% 3 2 3 11%	2834
	21st to end	Day	17% 22% 7% 16% 8% 6% 6% 3 3 3 9%	3553
January	1st to 10th	Night	11% 20% 10% 20% 9% 7% 5% 3 3 3 8%	8831
	11th to 20th	Night	7% 18% 9% 21% 10% 7% 7% 4 5% 3 8%	8561
	21st to end	Night	5% 12% 7% 17% 10% 11% 8% 7% 7% 4 13%	9015
February	1st to 10th	Night	9% 15% 5% 13% 11% 8% 7% 5% 7% 6% 15%	2730
	11th to 20th	Night	10% 18% 7% 13% 10% 7% 5% 5% 5% 6% 13%	2663
	21st to end	Night	9% 18% 6% 12% 9% 6% 8% 5% 6% 5% 18%	2192
March	1st to 10th	Night	15% 19% 6% 10% 7% 5% 4 4 5% 4 21%	5372
	11th to 20th	Night	19% 19% 6% 12% 6% 5% 5% 3 4 4 17%	5089
	21st to end	Night	13% 13% 5% 12% 5% 9% 6% 3 4 4 24%	5365
April	1st to 10th	Night	21% 15% 5% 12% 5% 4 3 2 5% 4 25%	2100
	11th to 20th	Night	18% 13% 4 9% 5% 4 3 4 5% 6% 28%	2026
	21st to end	Night	18% 12% 4 8% 5% 4 4 3 3 5% 33%	1801
May	1st to 10th	Night	18% 12% 4 8% 4 4 4 4 5% 6% 29%	4660
	11th to 20th	Night	19% 12% 3 8% 5% 4 4 4 5% 6% 32%	4639
	21st to end	Night	21% 10% 3 7% 4 4 4 4 6% 7% 31%	5114
June	1st to 10th	Night	21% 8% 2 6% 5% 4 5% 3 6% 8% 32%	1511
	11th to 20th	Night	18% 8% 3 8% 5% 4 4 4 6% 8% 33%	1470
	21st to end	Night	17% 7% 1 7% 7% 5% 4 4 6% 7% 33%	1470
July	1st to 10th	Night	20% 8% 3 8% 5% 3 4 4 5% 7% 33%	3160
	11th to 20th	Night	23% 8% 2 6% 4 4 4 3 5% 6% 35%	3221
	21st to end	Night	16% 7% 2 6% 3 4 4 4 6% 8% 40%	3926
August	1st to 10th	Night	16% 7% 2 7% 5% 5% 5% 5% 5% 7% 36%	2586
	11th to 20th	Night	16% 10% 3 7% 5% 4 3 3 5% 7% 38%	2857
	21st to end	Night	17% 8% 3 8% 5% 4 4 3 5% 8% 33%	3388
September	1st to 10th	Night	21% 10% 3 8% 4 4 3 3 5% 6% 35%	2000
	11th to 20th	Night	22% 9% 3 5% 4 3 5% 3 4 6% 37%	2000
	21st to end	Night	23% 10% 3 6% 4 4 3 3 3 5% 36%	2295
October	1st to 10th	Night	22% 11% 3 7% 5% 4 4 4 5% 7% 30%	2400
	11th to 20th	Night	28% 19% 4 8% 5% 4 4 3 3 4 17%	2400
	21st to end	Night	27% 21% 4 8% 5% 3 3 3 4 4 17%	2812
November	1st to 10th	Night	22% 21% 6% 10% 6% 4 3 3 4 5% 16%	2853
	11th to 20th	Night	21% 22% 6% 13% 6% 4 4 2 4 4 14%	2940
	21st to end	Night	22% 25% 8% 15% 6% 4 3 2 4 3 8%	2940
December	1st to 10th	Night	13% 24% 9% 18% 9% 8% 4 2 2 3 6%	4720
	11th to 20th	Night	17% 19% 7% 14% 9% 8% 6% 3 4 4 9%	5583
	21st to end	Night	18% 22% 8% 16% 8% 6% 4 3 3 3 9%	7667

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	86% 3 5% 5% 1	4095
	11th to 20th	Day	78% 4 5% 7% 7%	4354
	21st to end	Day	68% 4 7% 16% 6%	5164
February	1st to 10th	Day	69% 4 8% 12% 7%	1890
	11th to 20th	Day	71% 5% 6% 12% 5%	1852
	21st to end	Day	69% 3 7% 14% 6%	1613
March	1st to 10th	Day	68% 4 5% 13% 10% 1	4690
	11th to 20th	Day	68% 3 7% 12% 8% 1	5090
	21st to end	Day	64% 4 6% 17% 8% 1	5809
April	1st to 10th	Day	66% 3 8% 12% 10% 2	2520
	11th to 20th	Day	58% 5% 8% 16% 11% 2	2560
	21st to end	Day	59% 5% 7% 15% 12% 2	2819
May	1st to 10th	Day	57% 6% 8% 14% 13% 2	8249
	11th to 20th	Day	53% 7% 14% 19% 7%	8225
	21st to end	Day	51% 5% 7% 21% 13% 2	9061
June	1st to 10th	Day	54% 7% 9% 19% 10% 1	3105
	11th to 20th	Day	48% 7% 10% 21% 12% 2	3150
	21st to end	Day	51% 7% 11% 21% 9% 1	3150
July	1st to 10th	Day	53% 6% 13% 24% 5%	6747
	11th to 20th	Day	48% 6% 16% 24% 6%	6659
	21st to end	Day	50% 6% 13% 24% 7%	6728
August	1st to 10th	Day	52% 7% 15% 21% 4	4549
	11th to 20th	Day	53% 6% 14% 21% 7%	4227
	21st to end	Day	47% 6% 12% 25% 10%	4477
September	1st to 10th	Day	53% 7% 14% 19% 7% 1	2400
	11th to 20th	Day	54% 8% 14% 20% 4	2400
	21st to end	Day	56% 5% 11% 20% 7%	2103
October	1st to 10th	Day	61% 4 12% 18% 4 1	3260
	11th to 20th	Day	68% 4 12% 12% 3	3240
	21st to end	Day	73% 5% 11% 7% 4	3252
November	1st to 10th	Day	72% 5% 11% 8% 3	1661
	11th to 20th	Day	80% 4 6% 8% 2	1680
	21st to end	Day	87% 4 4 4 1	1680
December	1st to 10th	Day	85% 3 5% 6% 1	2680
	11th to 20th	Day	80% 3 4 10% 2	2833
	21st to end	Day	81% 4 5% 8% 2	3553
January	1st to 10th	Night	83% 4 5% 6% 2	8831
	11th to 20th	Night	82% 3 4 5% 6%	8607
	21st to end	Night	72% 4 4 16% 4	9015
February	1st to 10th	Night	67% 6% 8% 12% 8%	2730
	11th to 20th	Night	71% 5% 8% 10% 5%	2665
	21st to end	Night	66% 5% 8% 14% 7%	2192
March	1st to 10th	Night	66% 4 6% 11% 12% 2	5382
	11th to 20th	Night	71% 4 6% 11% 8%	5090
	21st to end	Night	62% 5% 7% 16% 7% 2	5365
April	1st to 10th	Night	62% 4 7% 15% 10% 2	2100
	11th to 20th	Night	56% 5% 10% 19% 9% 1	2026
	21st to end	Night	54% 5% 6% 19% 14% 2	1801
May	1st to 10th	Night	53% 6% 8% 18% 13% 2	4666
	11th to 20th	Night	51% 7% 10% 20% 10% 1	4640
	21st to end	Night	51% 6% 9% 19% 12% 3	5115
June	1st to 10th	Night	51% 6% 9% 19% 13% 1	1511
	11th to 20th	Night	48% 6% 11% 20% 12% 3	1470
	21st to end	Night	47% 8% 14% 20% 10% 1	1470
July	1st to 10th	Night	51% 4 12% 25% 8%	3125
	11th to 20th	Night	50% 5% 14% 23% 7%	3179
	21st to end	Night	42% 5% 17% 31% 5%	3809
August	1st to 10th	Night	47% 7% 14% 28% 5%	2576
	11th to 20th	Night	47% 6% 17% 23% 7%	2884
	21st to end	Night	48% 6% 14% 21% 9%	3388
September	1st to 10th	Night	51% 6% 15% 20% 8%	2000
	11th to 20th	Night	49% 6% 18% 22% 5%	2000
	21st to end	Night	51% 6% 12% 24% 6%	2295
October	1st to 10th	Night	57% 5% 12% 19% 6% 1	3920
	11th to 20th	Night	70% 4 10% 14% 2	3899
	21st to end	Night	68% 4 13% 9% 5%	4537
November	1st to 10th	Night	72% 6% 12% 9% 2	2853
	11th to 20th	Night	76% 5% 8% 7% 3	2940
	21st to end	Night	83% 5% 6% 6%	2940
December	1st to 10th	Night	86% 2 6% 5% 1	4720
	11th to 20th	Night	80% 3 7% 8% 2	5583
	21st to end	Night	81% 3 6% 8% 2	7667

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% 20% 41% 15% 3	220
	11th to 20th	Day	19% 15% 37% 19% 6% 4	220
	21st to end	Day	16% 14% 35% 26% 9%	250
February	1st to 10th	Day	17% 23% 38% 17% 4 1	330
	11th to 20th	Day	22% 22% 36% 16% 4	330
	21st to end	Day	23% 19% 37% 17% 4	329
March	1st to 10th	Day	25% 20% 32% 16% 6%	540
	11th to 20th	Day	30% 16% 34% 15% 5% 1	540
	21st to end	Day	24% 21% 32% 18% 4 1	594
April	1st to 10th	Day	26% 19% 29% 14% 9% 1	540
	11th to 20th	Day	30% 15% 31% 15% 6% 2	532
	21st to end	Day	30% 20% 27% 18% 4 1	540
May	1st to 10th	Day	22% 15% 33% 22% 8% 1	543
	11th to 20th	Day	26% 14% 33% 19% 6% 3	567
	21st to end	Day	27% 14% 33% 20% 5%	617
June	1st to 10th	Day	27% 14% 31% 21% 6% 1	735
	11th to 20th	Day	24% 14% 34% 19% 7% 1	780
	21st to end	Day	24% 12% 29% 25% 9% 2	780
July	1st to 10th	Day	20% 12% 34% 22% 9% 2	722
	11th to 20th	Day	20% 13% 32% 24% 11% 1	690
	21st to end	Day	22% 9% 32% 24% 10% 2	576
August	1st to 10th	Day	25% 8% 30% 23% 12% 3	526
	11th to 20th	Day	21% 9% 26% 25% 14% 5%	519
	21st to end	Day	27% 10% 28% 20% 11% 4	583
September	1st to 10th	Day	28% 12% 31% 17% 8% 3	530
	11th to 20th	Day	23% 11% 30% 23% 10% 2	530
	21st to end	Day	28% 13% 27% 18% 10% 3	530
October	1st to 10th	Day	30% 15% 25% 19% 8% 2	530
	11th to 20th	Day	38% 17% 28% 12% 4 1	530
	21st to end	Day	38% 11% 29% 15% 6% 1	487
November	1st to 10th	Day	37% 20% 32% 8% 3	235
	11th to 20th	Day	30% 18% 37% 10% 4 1	220
	21st to end	Day	42% 18% 26% 10% 3 1	220
December	1st to 10th	Day	22% 15% 33% 21% 7% 3	220
	11th to 20th	Day	30% 18% 38% 8% 5% 1	220
	21st to end	Day	34% 14% 31% 14% 7%	242
January	1st to 10th	Night	25% 12% 35% 22% 4 1	1050
	11th to 20th	Night	24% 14% 33% 23% 6% 1	959
	21st to end	Night	16% 11% 32% 28% 10% 2	924
February	1st to 10th	Night	14% 15% 36% 27% 7%	840
	11th to 20th	Night	20% 15% 36% 23% 6%	823
	21st to end	Night	19% 14% 39% 20% 8%	692
March	1st to 10th	Night	20% 18% 33% 22% 7%	840
	11th to 20th	Night	28% 16% 31% 20% 5%	840
	21st to end	Night	22% 15% 35% 23% 5% 1	924
April	1st to 10th	Night	29% 15% 30% 21% 7%	840
	11th to 20th	Night	26% 14% 27% 24% 8% 1	782
	21st to end	Night	25% 10% 34% 24% 6% 1	541
May	1st to 10th	Night	22% 10% 29% 30% 9% 1	420
	11th to 20th	Night	25% 9% 28% 30% 7% 1	414
	21st to end	Night	27% 9% 33% 27% 4	455
June	1st to 10th	Night	21% 10% 32% 27% 10%	420
	11th to 20th	Night	21% 10% 31% 28% 10%	420
	21st to end	Night	18% 5% 29% 32% 15% 1	420
July	1st to 10th	Night	22% 8% 26% 35% 9% 1	390
	11th to 20th	Night	22% 5% 24% 38% 10%	388
	21st to end	Night	18% 5% 24% 35% 17% 1	438
August	1st to 10th	Night	23% 5% 24% 28% 18% 2	398
	11th to 20th	Night	20% 5% 26% 30% 19% 1	576
	21st to end	Night	25% 7% 23% 27% 16% 2	760
September	1st to 10th	Night	26% 10% 27% 24% 12% 1	800
	11th to 20th	Night	26% 8% 27% 27% 11% 2	800
	21st to end	Night	28% 9% 23% 26% 13% 1	800
October	1st to 10th	Night	27% 11% 29% 24% 9%	800
	11th to 20th	Night	39% 12% 27% 17% 5% 1	800
	21st to end	Night	38% 11% 27% 17% 7% 1	880
November	1st to 10th	Night	34% 15% 31% 13% 6% 1	820
	11th to 20th	Night	35% 15% 28% 18% 5%	840
	21st to end	Night	36% 15% 31% 13% 4 1	840
December	1st to 10th	Night	33% 12% 31% 18% 5% 1	840
	11th to 20th	Night	25% 14% 32% 20% 7% 2	950
	21st to end	Night	30% 14% 28% 21% 6% 1	1155

Page generated at 2026-06-28 02:10:42. Version ac07

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