CEGEP Beauce-Appalaches
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the CEGEP Beauce-Appalaches clear sky chart from 2005-11-06 to 2026-06-01.

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% 12% 4 10% 6% 5% 5% 4 5% 6% 26%	131487
	Night	17% 14% 5% 11% 6% 5% 4 3 4 5% 25%	131707
Transparency	Day	58% 5% 10% 17% 8% 1	134955
	Night	61% 5% 10% 16% 7% 1	136327
Seeing	Day	28% 17% 28% 18% 7% 2	17276
	Night	26% 14% 28% 24% 8% 1	25859

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	13% 18% 8% 17% 8% 7% 6% 3 4 4 13%	4661
	11th to 20th	Day	11% 18% 9% 24% 11% 4 3 2 2 2 13%	4650
	21st to end	Day	6% 11% 7% 17% 8% 11% 7% 5% 5% 5% 17%	5124
February	1st to 10th	Day	12% 16% 6% 13% 10% 7% 4 3 4 4 20%	1735
	11th to 20th	Day	13% 19% 8% 14% 6% 5% 4 3 3 4 20%	2021
	21st to end	Day	12% 16% 6% 14% 6% 6% 4 4 5% 5% 22%	1730
March	1st to 10th	Day	19% 17% 5% 13% 6% 5% 3 2 3 4 22%	4576
	11th to 20th	Day	16% 17% 4 10% 5% 4 4 3 5% 5% 26%	4920
	21st to end	Day	20% 16% 5% 10% 5% 4 3 2 4 4 26%	5855
April	1st to 10th	Day	22% 17% 4 10% 4 3 3 2 4 5% 25%	2520
	11th to 20th	Day	21% 13% 4 7% 4 4 3 3 3 5% 34%	2612
	21st to end	Day	24% 12% 3 8% 5% 3 3 3 4 6% 29%	2730
May	1st to 10th	Day	26% 11% 3 8% 6% 5% 5% 3 5% 5% 22%	6016
	11th to 20th	Day	23% 9% 3 7% 5% 5% 5% 4 6% 7% 26%	6446
	21st to end	Day	19% 9% 3 8% 6% 5% 5% 4 6% 7% 28%	7168
June	1st to 10th	Day	23% 10% 2 6% 5% 5% 5% 4 7% 8% 26%	3000
	11th to 20th	Day	19% 8% 3 6% 5% 5% 6% 4 6% 8% 32%	3000
	21st to end	Day	21% 10% 4 9% 7% 5% 5% 4 5% 6% 24%	3000
July	1st to 10th	Day	16% 8% 4 9% 7% 6% 6% 5% 8% 8% 23%	6414
	11th to 20th	Day	14% 7% 3 8% 5% 5% 6% 5% 8% 9% 32%	6360
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 7% 9% 40%	6926
August	1st to 10th	Day	16% 7% 3 8% 6% 6% 6% 6% 7% 8% 28%	4445
	11th to 20th	Day	18% 7% 3 9% 7% 6% 6% 5% 7% 8% 26%	4175
	21st to end	Day	19% 8% 3 7% 4 5% 5% 3 5% 7% 35%	4511
September	1st to 10th	Day	16% 7% 2 7% 4 4 5% 4 5% 7% 37%	2393
	11th to 20th	Day	17% 7% 2 5% 3 3 4 4 5% 7% 42%	2200
	21st to end	Day	18% 8% 3 6% 4 4 4 4 6% 9% 34%	2200
October	1st to 10th	Day	20% 10% 3 6% 4 5% 4 3 5% 7% 32%	2200
	11th to 20th	Day	20% 13% 4 9% 6% 6% 4 3 4 5% 26%	1853
	21st to end	Day	24% 17% 5% 9% 4 4 4 3 4 5% 21%	1980
November	1st to 10th	Day	19% 18% 5% 8% 5% 4 4 3 4 5% 26%	1851
	11th to 20th	Day	18% 18% 7% 12% 4 4 3 2 4 4 24%	1890
	21st to end	Day	20% 19% 6% 13% 6% 4 3 3 4 5% 18%	1580
December	1st to 10th	Day	17% 18% 7% 15% 7% 5% 5% 3 4 3 16%	2350
	11th to 20th	Day	18% 16% 6% 11% 6% 4 3 3 4 4 23%	2688
	21st to end	Day	18% 19% 5% 14% 5% 4 4 4 4 4 18%	3707
January	1st to 10th	Night	12% 16% 8% 20% 8% 6% 5% 3 4 4 13%	8234
	11th to 20th	Night	10% 21% 9% 22% 10% 5% 3 3 3 3 11%	8235
	21st to end	Night	6% 13% 6% 15% 10% 9% 7% 6% 5% 5% 18%	9057
February	1st to 10th	Night	11% 16% 5% 13% 9% 6% 5% 2 4 5% 23%	2883
	11th to 20th	Night	12% 17% 7% 16% 7% 6% 5% 3 3 4 21%	2484
	21st to end	Night	12% 18% 6% 10% 7% 4 4 3 4 4 28%	2076
March	1st to 10th	Night	20% 16% 5% 11% 6% 5% 5% 2 3 5% 22%	5484
	11th to 20th	Night	16% 16% 5% 10% 6% 5% 5% 3 4 6% 25%	5259
	21st to end	Night	20% 16% 5% 10% 5% 3 3 3 4 5% 27%	5317
April	1st to 10th	Night	23% 16% 4 7% 4 3 3 3 5% 5% 27%	2100
	11th to 20th	Night	20% 13% 2 7% 5% 4 4 3 4 6% 31%	1956
	21st to end	Night	22% 12% 3 8% 5% 4 3 3 4 5% 30%	1890
May	1st to 10th	Night	24% 10% 3 9% 5% 5% 5% 4 6% 6% 24%	4144
	11th to 20th	Night	24% 9% 3 7% 5% 4 4 3 4 5% 31%	3712
	21st to end	Night	20% 8% 3 6% 4 4 5% 4 5% 7% 35%	3937
June	1st to 10th	Night	23% 10% 3 8% 5% 4 5% 3 5% 6% 28%	1400
	11th to 20th	Night	18% 7% 3 7% 4 4 4 4 6% 7% 35%	1400
	21st to end	Night	19% 7% 3 9% 4 5% 5% 4 5% 7% 32%	1400
July	1st to 10th	Night	17% 9% 3 8% 5% 5% 5% 4 6% 8% 31%	3543
	11th to 20th	Night	19% 6% 2 8% 4 4 4 3 5% 7% 37%	3600
	21st to end	Night	13% 7% 2 7% 5% 4 5% 4 6% 9% 39%	3926
August	1st to 10th	Night	19% 7% 3 7% 5% 4 4 4 6% 8% 34%	2671
	11th to 20th	Night	15% 8% 3 10% 6% 6% 6% 4 6% 7% 30%	2872
	21st to end	Night	17% 8% 3 7% 4 4 5% 4 5% 7% 37%	3383
September	1st to 10th	Night	15% 7% 3 6% 5% 4 4 3 6% 7% 39%	2006
	11th to 20th	Night	16% 6% 2 6% 4 4 3 4 5% 6% 45%	2200
	21st to end	Night	17% 7% 3 6% 4 4 4 3 5% 7% 41%	2200
October	1st to 10th	Night	19% 8% 3 6% 4 3 4 4 5% 6% 38%	2200
	11th to 20th	Night	21% 10% 3 8% 6% 4 4 3 4 6% 30%	2544
	21st to end	Night	22% 15% 4 8% 4 3 4 3 5% 5% 28%	2860
November	1st to 10th	Night	21% 15% 4 8% 5% 4 4 4 4 5% 27%	2667
	11th to 20th	Night	18% 14% 6% 10% 5% 4 4 2 4 5% 27%	2730
	21st to end	Night	19% 20% 6% 10% 5% 4 3 3 4 4 21%	3034
December	1st to 10th	Night	16% 18% 10% 18% 9% 5% 4 3 3 3 12%	5060
	11th to 20th	Night	18% 18% 6% 16% 8% 4 4 2 3 4 16%	5741
	21st to end	Night	19% 19% 6% 10% 5% 4 4 3 4 5% 22%	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	77% 4 6% 10% 3	4662
	11th to 20th	Day	79% 4 3 9% 5% 1	4680
	21st to end	Day	70% 5% 4 11% 10%	5124
February	1st to 10th	Day	70% 4 4 13% 7% 2	1735
	11th to 20th	Day	71% 3 7% 11% 6% 1	2030
	21st to end	Day	64% 5% 8% 15% 6% 2	1730
March	1st to 10th	Day	67% 3 6% 10% 9% 4	4579
	11th to 20th	Day	59% 6% 13% 14% 8% 1	4920
	21st to end	Day	62% 4 4 14% 13% 2	5855
April	1st to 10th	Day	63% 3 8% 14% 9% 2	2520
	11th to 20th	Day	55% 4 8% 21% 12% 1	2612
	21st to end	Day	57% 4 8% 18% 10% 2	2730
May	1st to 10th	Day	63% 6% 7% 16% 7% 1	6027
	11th to 20th	Day	56% 7% 14% 16% 6% 2	6450
	21st to end	Day	53% 7% 10% 17% 10% 2	7168
June	1st to 10th	Day	55% 6% 10% 21% 7% 1	3000
	11th to 20th	Day	49% 6% 13% 22% 10% 1	3000
	21st to end	Day	60% 6% 9% 17% 8%	3000
July	1st to 10th	Day	55% 7% 15% 17% 6%	6344
	11th to 20th	Day	46% 7% 16% 26% 5%	6285
	21st to end	Day	41% 6% 15% 30% 8%	6728
August	1st to 10th	Day	51% 8% 16% 20% 5%	4431
	11th to 20th	Day	54% 8% 16% 17% 5%	4214
	21st to end	Day	49% 6% 14% 20% 11% 1	4511
September	1st to 10th	Day	44% 7% 15% 23% 10% 1	2393
	11th to 20th	Day	41% 5% 13% 29% 12%	2200
	21st to end	Day	45% 7% 12% 25% 11%	2200
October	1st to 10th	Day	55% 5% 11% 24% 6%	3590
	11th to 20th	Day	56% 4 13% 25% 2	2991
	21st to end	Day	55% 5% 14% 18% 7%	3180
November	1st to 10th	Day	62% 5% 10% 17% 6%	1851
	11th to 20th	Day	65% 4 9% 14% 7% 1	1890
	21st to end	Day	70% 5% 10% 12% 3	1580
December	1st to 10th	Day	74% 4 8% 9% 5%	2350
	11th to 20th	Day	65% 5% 7% 14% 9%	2688
	21st to end	Day	69% 4 7% 9% 9% 1	3707
January	1st to 10th	Night	75% 6% 7% 7% 4	8234
	11th to 20th	Night	81% 6% 3 7% 3	8280
	21st to end	Night	67% 6% 6% 11% 10% 1	9057
February	1st to 10th	Night	66% 4 7% 14% 8% 1	2883
	11th to 20th	Night	70% 5% 5% 12% 7% 1	2486
	21st to end	Night	61% 4 7% 16% 11% 1	2076
March	1st to 10th	Night	67% 4 7% 13% 9% 1	5494
	11th to 20th	Night	61% 6% 14% 11% 7% 1	5260
	21st to end	Night	61% 3 5% 18% 11% 1	5317
April	1st to 10th	Night	60% 4 6% 16% 12% 2	2100
	11th to 20th	Night	56% 4 7% 21% 11% 2	1956
	21st to end	Night	57% 6% 8% 16% 12% 2	1890
May	1st to 10th	Night	59% 5% 11% 17% 8% 1	4150
	11th to 20th	Night	54% 5% 12% 22% 7%	3713
	21st to end	Night	48% 6% 15% 17% 14%	3938
June	1st to 10th	Night	57% 5% 10% 19% 8%	1400
	11th to 20th	Night	46% 7% 11% 23% 11% 2	1400
	21st to end	Night	52% 7% 13% 19% 9%	1400
July	1st to 10th	Night	49% 7% 19% 20% 5%	3503
	11th to 20th	Night	47% 6% 18% 23% 5%	3552
	21st to end	Night	43% 7% 17% 27% 6%	3809
August	1st to 10th	Night	49% 6% 17% 24% 4	2661
	11th to 20th	Night	51% 9% 17% 17% 6% 1	2899
	21st to end	Night	46% 6% 14% 21% 13%	3383
September	1st to 10th	Night	43% 6% 14% 27% 9% 1	2006
	11th to 20th	Night	40% 5% 15% 30% 9%	2200
	21st to end	Night	43% 7% 12% 25% 13%	2200
October	1st to 10th	Night	47% 5% 12% 26% 9%	3590
	11th to 20th	Night	55% 4 12% 26% 3	4145
	21st to end	Night	52% 4 16% 19% 9%	4610
November	1st to 10th	Night	60% 6% 11% 17% 5%	2667
	11th to 20th	Night	61% 5% 11% 14% 9% 1	2730
	21st to end	Night	67% 5% 10% 13% 4	3034
December	1st to 10th	Night	79% 4 7% 8% 2	5060
	11th to 20th	Night	73% 5% 5% 14% 4	5742
	21st to end	Night	66% 3 8% 14% 8%	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	27% 23% 34% 14% 2	220
	11th to 20th	Day	34% 24% 27% 11% 4	220
	21st to end	Day	24% 23% 36% 14% 2 1	242
February	1st to 10th	Day	32% 20% 28% 11% 8%	275
	11th to 20th	Day	27% 26% 31% 13% 3	522
	21st to end	Day	26% 26% 30% 15% 3	446
March	1st to 10th	Day	30% 24% 28% 12% 5%	540
	11th to 20th	Day	32% 22% 28% 12% 4 1	540
	21st to end	Day	35% 19% 26% 12% 6% 2	594
April	1st to 10th	Day	39% 18% 25% 12% 4 1	540
	11th to 20th	Day	37% 20% 24% 14% 5% 2	532
	21st to end	Day	33% 20% 27% 13% 5% 2	540
May	1st to 10th	Day	36% 16% 28% 15% 3 1	543
	11th to 20th	Day	29% 16% 29% 19% 6% 2	567
	21st to end	Day	24% 22% 33% 16% 5% 1	643
June	1st to 10th	Day	29% 13% 28% 22% 6% 1	730
	11th to 20th	Day	24% 14% 27% 24% 10% 1	730
	21st to end	Day	27% 13% 30% 19% 9% 1	730
July	1st to 10th	Day	20% 13% 35% 22% 8% 1	553
	11th to 20th	Day	19% 13% 36% 21% 10% 1	524
	21st to end	Day	23% 13% 30% 26% 8% 1	576
August	1st to 10th	Day	19% 12% 29% 26% 11% 3	526
	11th to 20th	Day	23% 8% 26% 25% 16% 3	519
	21st to end	Day	24% 13% 25% 22% 10% 5%	583
September	1st to 10th	Day	18% 14% 30% 21% 12% 5%	530
	11th to 20th	Day	23% 10% 24% 20% 16% 7%	530
	21st to end	Day	23% 16% 22% 21% 12% 6%	530
October	1st to 10th	Day	25% 15% 24% 19% 13% 4	530
	11th to 20th	Day	33% 14% 24% 16% 11% 2	425
	21st to end	Day	37% 17% 25% 16% 5%	462
November	1st to 10th	Day	37% 14% 27% 17% 4	425
	11th to 20th	Day	28% 21% 25% 16% 9% 1	430
	21st to end	Day	36% 19% 26% 14% 4 1	297
December	1st to 10th	Day	33% 17% 26% 16% 7%	220
	11th to 20th	Day	39% 22% 22% 12% 5% 1	220
	21st to end	Day	33% 21% 25% 14% 5% 1	242
January	1st to 10th	Night	26% 21% 31% 18% 3	840
	11th to 20th	Night	28% 19% 32% 18% 3	840
	21st to end	Night	20% 16% 36% 22% 5%	924
February	1st to 10th	Night	22% 21% 33% 19% 5%	840
	11th to 20th	Night	26% 19% 33% 19% 3	823
	21st to end	Night	26% 17% 33% 21% 3	692
March	1st to 10th	Night	28% 16% 34% 19% 3	840
	11th to 20th	Night	28% 18% 31% 18% 5%	840
	21st to end	Night	27% 16% 27% 22% 7% 1	924
April	1st to 10th	Night	35% 14% 28% 19% 4	840
	11th to 20th	Night	29% 13% 28% 24% 6%	712
	21st to end	Night	30% 18% 26% 20% 6%	630
May	1st to 10th	Night	27% 11% 31% 24% 7% 1	630
	11th to 20th	Night	23% 11% 30% 31% 6%	445
	21st to end	Night	27% 7% 28% 30% 8%	455
June	1st to 10th	Night	30% 7% 22% 33% 8% 1	400
	11th to 20th	Night	23% 8% 22% 34% 13% 1	400
	21st to end	Night	20% 8% 32% 30% 11% 1	400
July	1st to 10th	Night	18% 9% 30% 31% 12% 1	390
	11th to 20th	Night	19% 4 23% 41% 13%	388
	21st to end	Night	18% 5% 23% 44% 11%	438
August	1st to 10th	Night	16% 5% 18% 41% 20%	444
	11th to 20th	Night	17% 6% 23% 35% 18% 1	592
	21st to end	Night	17% 8% 24% 33% 16% 2	755
September	1st to 10th	Night	19% 9% 26% 30% 14% 2	800
	11th to 20th	Night	22% 7% 20% 30% 19% 2	800
	21st to end	Night	22% 8% 26% 27% 15% 1	800
October	1st to 10th	Night	24% 10% 23% 32% 11%	800
	11th to 20th	Night	30% 12% 25% 24% 9% 1	800
	21st to end	Night	33% 14% 28% 20% 6%	880
November	1st to 10th	Night	32% 14% 24% 23% 6%	820
	11th to 20th	Night	28% 14% 27% 21% 8% 1	840
	21st to end	Night	31% 18% 28% 18% 5% 1	931
December	1st to 10th	Night	33% 17% 27% 18% 5%	950
	11th to 20th	Night	31% 20% 24% 18% 6%	950
	21st to end	Night	33% 19% 25% 18% 4	1006

Page generated at 2026-05-29 01:53:27. Version ac07

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