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 2025-02-25.

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%	108477
	Night	16% 15% 6% 12% 7% 5% 5% 4 5% 5% 20%	110262
Transparency	Day	61% 6% 10% 16% 7% 1	111978
	Night	66% 5% 9% 14% 6%	114925
Seeing	Day	26% 14% 31% 19% 7% 2	15275
	Night	26% 12% 30% 23% 8% 1	24263

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% 22% 10% 21% 7% 9% 5% 3 4 3 5%	3158
	11th to 20th	Day	9% 15% 9% 20% 10% 5% 7% 6% 8% 4 7%	3323
	21st to end	Day	7% 15% 8% 17% 7% 7% 8% 5% 6% 6% 15%	3986
February	1st to 10th	Day	7% 16% 6% 15% 10% 10% 6% 5% 5% 5% 15%	1800
	11th to 20th	Day	10% 20% 6% 14% 9% 6% 7% 5% 6% 5% 13%	1753
	21st to end	Day	12% 17% 7% 14% 9% 5% 6% 3 5% 5% 17%	1499
March	1st to 10th	Day	21% 17% 3 9% 5% 4 4 3 4 5% 26%	3197
	11th to 20th	Day	12% 15% 6% 18% 7% 4 4 2 4 4 23%	3480
	21st to end	Day	12% 13% 7% 16% 7% 6% 5% 3 4 4 24%	3964
April	1st to 10th	Day	20% 19% 5% 11% 5% 4 4 2 3 5% 23%	2280
	11th to 20th	Day	19% 14% 5% 9% 4 4 4 3 5% 6% 29%	2314
	21st to end	Day	20% 14% 3 8% 5% 4 4 3 4 5% 28%	2551
May	1st to 10th	Day	17% 12% 4 8% 6% 5% 5% 4 6% 6% 26%	4426
	11th to 20th	Day	17% 10% 3 8% 6% 6% 6% 4 6% 7% 27%	4398
	21st to end	Day	20% 8% 3 7% 5% 5% 5% 4 6% 7% 32%	4837
June	1st to 10th	Day	24% 8% 3 7% 5% 5% 5% 4 6% 7% 26%	2809
	11th to 20th	Day	15% 9% 3 6% 5% 4 5% 4 6% 8% 34%	2850
	21st to end	Day	21% 8% 3 6% 6% 4 4 4 6% 7% 31%	2850
July	1st to 10th	Day	19% 7% 2 8% 6% 6% 5% 5% 6% 9% 27%	4760
	11th to 20th	Day	18% 7% 3 7% 5% 5% 5% 4 6% 8% 31%	4708
	21st to end	Day	17% 7% 3 7% 4 5% 5% 4 6% 8% 33%	4814
August	1st to 10th	Day	19% 8% 3 8% 5% 6% 6% 5% 6% 8% 26%	4423
	11th to 20th	Day	21% 9% 3 7% 5% 5% 5% 4 5% 5% 31%	4057
	21st to end	Day	17% 8% 3 7% 4 4 5% 3 5% 8% 35%	4340
September	1st to 10th	Day	24% 9% 2 6% 3 5% 4 4 5% 7% 31%	2280
	11th to 20th	Day	23% 10% 2 7% 4 5% 5% 3 6% 6% 28%	2280
	21st to end	Day	25% 11% 3 8% 5% 5% 3 3 4 5% 30%	1998
October	1st to 10th	Day	24% 13% 3 7% 5% 3 3 3 4 5% 29%	1900
	11th to 20th	Day	31% 20% 5% 9% 4 3 3 2 3 4 15%	1900
	21st to end	Day	30% 21% 6% 9% 4 3 3 3 4 3 15%	1926
November	1st to 10th	Day	22% 24% 6% 10% 5% 4 3 3 4 4 16%	1580
	11th to 20th	Day	23% 24% 9% 12% 6% 4 3 2 4 4 11%	1600
	21st to end	Day	23% 28% 9% 15% 6% 4 3 2 2 2 7%	1600
December	1st to 10th	Day	12% 29% 10% 17% 8% 6% 3 2 3 3 7%	2600
	11th to 20th	Day	15% 21% 6% 14% 13% 5% 7% 3 2 3 12%	2760
	21st to end	Day	18% 23% 7% 16% 8% 6% 6% 3 3 3 9%	3476
January	1st to 10th	Night	11% 21% 10% 22% 9% 7% 5% 3 3 2 8%	6808
	11th to 20th	Night	8% 17% 9% 22% 11% 7% 6% 4 5% 3 8%	6571
	21st to end	Night	6% 15% 9% 16% 8% 9% 8% 6% 6% 4 13%	6968
February	1st to 10th	Night	9% 15% 5% 13% 11% 8% 7% 5% 7% 6% 15%	2600
	11th to 20th	Night	10% 18% 8% 14% 10% 7% 5% 5% 4 6% 12%	2533
	21st to end	Night	10% 18% 6% 12% 8% 6% 8% 5% 6% 5% 18%	2049
March	1st to 10th	Night	15% 17% 4 9% 6% 5% 6% 4 5% 5% 25%	3642
	11th to 20th	Night	16% 20% 6% 12% 5% 5% 4 3 4 5% 19%	3479
	21st to end	Night	13% 12% 5% 13% 6% 6% 7% 4 4 4 26%	3668
April	1st to 10th	Night	21% 15% 4 11% 5% 4 3 2 5% 4 27%	1900
	11th to 20th	Night	19% 13% 4 8% 5% 4 4 5% 6% 6% 27%	1831
	21st to end	Night	19% 12% 5% 8% 5% 4 3 3 3 5% 33%	1629
May	1st to 10th	Night	20% 10% 4 8% 4 4 4 4 6% 6% 30%	2514
	11th to 20th	Night	16% 9% 3 8% 5% 4 4 4 6% 7% 33%	2495
	21st to end	Night	21% 7% 2 6% 5% 4 4 4 7% 9% 30%	2738
June	1st to 10th	Night	22% 8% 2 6% 6% 4 5% 3 6% 8% 30%	1367
	11th to 20th	Night	18% 7% 3 7% 4 4 4 4 6% 8% 34%	1330
	21st to end	Night	17% 7% 2 7% 7% 5% 4 5% 6% 7% 34%	1330
July	1st to 10th	Night	20% 7% 3 6% 5% 3 4 4 6% 8% 35%	2210
	11th to 20th	Night	21% 8% 2 7% 5% 4 4 4 5% 7% 33%	2258
	21st to end	Night	17% 7% 2 6% 4 4 5% 4 6% 8% 37%	2739
August	1st to 10th	Night	16% 7% 2 7% 5% 5% 5% 5% 5% 7% 35%	2506
	11th to 20th	Night	16% 10% 3 8% 5% 4 3 3 5% 7% 38%	2768
	21st to end	Night	17% 8% 3 8% 5% 4 4 3 5% 8% 33%	3284
September	1st to 10th	Night	21% 10% 3 7% 4 4 3 3 5% 6% 35%	1900
	11th to 20th	Night	22% 8% 3 5% 4 3 5% 3 4 6% 37%	1900
	21st to end	Night	23% 10% 3 6% 4 4 3 3 3 5% 35%	2180
October	1st to 10th	Night	22% 11% 3 7% 5% 4 4 4 5% 7% 29%	2280
	11th to 20th	Night	28% 20% 4 8% 5% 4 4 3 3 4 17%	2280
	21st to end	Night	27% 22% 4 8% 5% 3 3 3 4 4 16%	2671
November	1st to 10th	Night	22% 21% 6% 10% 6% 4 3 3 4 5% 16%	2714
	11th to 20th	Night	21% 22% 6% 12% 6% 4 4 2 4 4 14%	2800
	21st to end	Night	22% 25% 8% 14% 6% 4 3 2 4 3 9%	2800
December	1st to 10th	Night	14% 24% 9% 18% 9% 8% 4 2 2 3 6%	4580
	11th to 20th	Night	17% 19% 7% 13% 9% 8% 6% 3 4 4 10%	5438
	21st to end	Night	18% 22% 8% 16% 8% 6% 4 3 3 3 9%	7502

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	85% 3 6% 4 1	3159
	11th to 20th	Day	76% 4 6% 8% 6%	3352
	21st to end	Day	69% 4 6% 14% 6%	3986
February	1st to 10th	Day	69% 4 7% 12% 7%	1800
	11th to 20th	Day	72% 5% 6% 11% 5%	1762
	21st to end	Day	70% 3 8% 13% 5%	1499
March	1st to 10th	Day	61% 5% 7% 17% 11%	3200
	11th to 20th	Day	65% 4 7% 13% 10% 2	3480
	21st to end	Day	62% 5% 7% 16% 9% 1	3964
April	1st to 10th	Day	65% 3 8% 11% 10% 2	2280
	11th to 20th	Day	57% 5% 9% 17% 10% 2	2314
	21st to end	Day	58% 5% 8% 14% 13% 2	2551
May	1st to 10th	Day	52% 9% 11% 19% 7% 1	4440
	11th to 20th	Day	50% 10% 13% 19% 7% 1	4402
	21st to end	Day	48% 9% 11% 20% 13%	4837
June	1st to 10th	Day	54% 7% 10% 19% 8% 1	2809
	11th to 20th	Day	47% 8% 10% 22% 11% 2	2850
	21st to end	Day	51% 8% 11% 20% 9% 1	2850
July	1st to 10th	Day	52% 6% 13% 24% 5%	4686
	11th to 20th	Day	48% 7% 16% 21% 8% 1	4627
	21st to end	Day	48% 6% 15% 24% 8%	4661
August	1st to 10th	Day	53% 7% 15% 21% 4	4409
	11th to 20th	Day	53% 6% 13% 21% 7%	4096
	21st to end	Day	47% 6% 11% 26% 10%	4340
September	1st to 10th	Day	52% 7% 14% 19% 8% 1	2280
	11th to 20th	Day	55% 8% 14% 19% 4	2280
	21st to end	Day	58% 5% 11% 19% 7%	1998
October	1st to 10th	Day	62% 4 11% 18% 4 1	3160
	11th to 20th	Day	69% 4 12% 12% 3	3140
	21st to end	Day	73% 5% 12% 6% 4	3151
November	1st to 10th	Day	72% 5% 12% 8% 3	1580
	11th to 20th	Day	79% 4 7% 8% 2	1600
	21st to end	Day	86% 4 5% 4 1	1600
December	1st to 10th	Day	86% 3 5% 6% 1	2600
	11th to 20th	Day	80% 3 5% 11% 2	2759
	21st to end	Day	81% 4 5% 8% 3	3476
January	1st to 10th	Night	84% 4 6% 4 2	6808
	11th to 20th	Night	80% 4 5% 6% 5%	6617
	21st to end	Night	72% 5% 5% 14% 4	6968
February	1st to 10th	Night	67% 6% 8% 12% 8%	2600
	11th to 20th	Night	72% 5% 8% 10% 5%	2535
	21st to end	Night	66% 5% 8% 14% 6%	2049
March	1st to 10th	Night	61% 5% 8% 14% 11% 1	3652
	11th to 20th	Night	67% 4 7% 13% 8% 1	3480
	21st to end	Night	59% 6% 10% 14% 9% 2	3668
April	1st to 10th	Night	60% 4 7% 15% 11% 2	1900
	11th to 20th	Night	56% 5% 10% 20% 8% 1	1831
	21st to end	Night	55% 5% 6% 18% 13% 2	1629
May	1st to 10th	Night	48% 10% 13% 18% 10% 1	2520
	11th to 20th	Night	46% 10% 12% 21% 10% 1	2496
	21st to end	Night	48% 9% 12% 19% 12% 1	2739
June	1st to 10th	Night	52% 7% 10% 19% 11% 1	1367
	11th to 20th	Night	46% 6% 11% 21% 12% 3	1330
	21st to end	Night	46% 9% 14% 20% 11%	1330
July	1st to 10th	Night	47% 5% 13% 28% 6%	2175
	11th to 20th	Night	50% 7% 15% 21% 7% 1	2216
	21st to end	Night	45% 6% 15% 29% 5%	2651
August	1st to 10th	Night	47% 7% 14% 27% 4	2496
	11th to 20th	Night	47% 6% 17% 23% 8%	2795
	21st to end	Night	48% 6% 14% 22% 10%	3284
September	1st to 10th	Night	50% 6% 15% 20% 9%	1900
	11th to 20th	Night	49% 7% 18% 21% 5%	1900
	21st to end	Night	53% 6% 12% 23% 6%	2180
October	1st to 10th	Night	58% 5% 12% 19% 5% 1	3800
	11th to 20th	Night	71% 4 10% 14% 1	3779
	21st to end	Night	68% 4 13% 9% 5% 1	4396
November	1st to 10th	Night	71% 6% 12% 9% 2	2714
	11th to 20th	Night	76% 5% 8% 7% 4	2800
	21st to end	Night	82% 5% 6% 6%	2800
December	1st to 10th	Night	86% 2 6% 5% 1	4580
	11th to 20th	Night	80% 3 7% 8% 2	5438
	21st to end	Night	81% 3 6% 8% 2	7502

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	19% 22% 40% 16% 3 1	200
	11th to 20th	Day	18% 14% 39% 20% 7% 4	200
	21st to end	Day	18% 15% 34% 26% 8%	227
February	1st to 10th	Day	17% 25% 39% 15% 3	300
	11th to 20th	Day	22% 23% 36% 16% 4	300
	21st to end	Day	24% 21% 36% 15% 4	287
March	1st to 10th	Day	23% 19% 34% 17% 7%	460
	11th to 20th	Day	26% 17% 34% 17% 6% 1	460
	21st to end	Day	24% 20% 33% 18% 4 1	506
April	1st to 10th	Day	26% 17% 30% 15% 10% 2	460
	11th to 20th	Day	28% 15% 32% 15% 7% 2	452
	21st to end	Day	29% 20% 28% 18% 4 1	460
May	1st to 10th	Day	22% 15% 32% 22% 7% 1	463
	11th to 20th	Day	27% 13% 31% 19% 7% 3	487
	21st to end	Day	25% 14% 35% 21% 5% 1	529
June	1st to 10th	Day	28% 13% 31% 20% 6% 1	639
	11th to 20th	Day	24% 14% 33% 20% 7% 2	680
	21st to end	Day	23% 12% 29% 25% 9% 2	680
July	1st to 10th	Day	20% 13% 33% 23% 9% 3	671
	11th to 20th	Day	19% 12% 32% 24% 11% 1	642
	21st to end	Day	22% 8% 31% 25% 11% 3	532
August	1st to 10th	Day	26% 7% 30% 23% 11% 2	486
	11th to 20th	Day	22% 8% 25% 25% 15% 5%	479
	21st to end	Day	26% 10% 29% 20% 10% 5%	539
September	1st to 10th	Day	28% 12% 31% 17% 9% 3	490
	11th to 20th	Day	24% 11% 31% 23% 9% 2	490
	21st to end	Day	29% 13% 27% 18% 10% 3	490
October	1st to 10th	Day	32% 14% 23% 20% 9% 2	490
	11th to 20th	Day	38% 17% 28% 12% 4 1	490
	21st to end	Day	39% 12% 30% 13% 5%	452
November	1st to 10th	Day	39% 19% 31% 8% 3	214
	11th to 20th	Day	30% 19% 36% 11% 4 1	200
	21st to end	Day	42% 17% 29% 10% 3 1	200
December	1st to 10th	Day	22% 14% 33% 22% 7% 3	200
	11th to 20th	Day	28% 18% 39% 9% 6% 2	200
	21st to end	Day	34% 14% 29% 15% 7%	220
January	1st to 10th	Night	26% 13% 35% 22% 5% 1	1000
	11th to 20th	Night	24% 14% 33% 23% 6% 1	914
	21st to end	Night	17% 11% 31% 28% 11% 2	880
February	1st to 10th	Night	15% 15% 36% 26% 7% 1	800
	11th to 20th	Night	20% 14% 36% 23% 6%	783
	21st to end	Night	19% 15% 39% 21% 7%	647
March	1st to 10th	Night	18% 18% 33% 22% 8%	760
	11th to 20th	Night	28% 16% 30% 20% 5%	760
	21st to end	Night	22% 14% 35% 24% 5% 1	836
April	1st to 10th	Night	28% 14% 29% 22% 7%	760
	11th to 20th	Night	27% 15% 26% 24% 8% 1	707
	21st to end	Night	25% 10% 33% 25% 7% 1	489
May	1st to 10th	Night	21% 10% 29% 30% 9% 1	380
	11th to 20th	Night	24% 9% 28% 30% 7% 1	374
	21st to end	Night	26% 9% 33% 27% 5%	411
June	1st to 10th	Night	22% 10% 31% 28% 9%	380
	11th to 20th	Night	20% 10% 30% 29% 10%	380
	21st to end	Night	18% 5% 28% 33% 14% 1	380
July	1st to 10th	Night	22% 8% 25% 35% 9% 1	370
	11th to 20th	Night	21% 5% 24% 39% 10%	368
	21st to end	Night	18% 5% 23% 35% 18% 1	416
August	1st to 10th	Night	25% 5% 23% 29% 17% 2	378
	11th to 20th	Night	20% 5% 24% 30% 19% 1	547
	21st to end	Night	24% 7% 23% 27% 16% 2	722
September	1st to 10th	Night	26% 10% 27% 24% 12% 1	760
	11th to 20th	Night	26% 8% 28% 26% 10% 1	760
	21st to end	Night	29% 9% 24% 26% 13%	760
October	1st to 10th	Night	28% 11% 28% 23% 9%	760
	11th to 20th	Night	39% 12% 26% 17% 5% 1	760
	21st to end	Night	39% 11% 27% 16% 7% 1	836
November	1st to 10th	Night	34% 14% 31% 14% 6% 1	780
	11th to 20th	Night	35% 15% 29% 17% 5%	800
	21st to end	Night	36% 15% 31% 13% 4 1	800
December	1st to 10th	Night	34% 12% 30% 19% 5% 1	800
	11th to 20th	Night	25% 13% 31% 21% 8% 2	905
	21st to end	Night	30% 14% 28% 21% 7% 1	1100

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