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 2024-01-27.

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	19% 11% 5% 8% 6% 3 5% 4 5% 6% 27%	74665
	Night	18% 12% 5% 8% 7% 3 4 4 4 5% 28%	75381
Transparency	Day	58% 5% 10% 17% 8% 1	74370
	Night	59% 6% 10% 17% 8% 1	75211
Seeing	Day	28% 17% 28% 18% 8% 2	14216
	Night	27% 14% 28% 24% 8% 1	22879

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	16% 18% 8% 14% 10% 4 5% 4 4 4 13%	1517
	11th to 20th	Day	16% 18% 8% 11% 10% 3 3 3 3 4 20%	1520
	21st to end	Day	10% 13% 6% 13% 10% 4 5% 5% 5% 6% 24%	1632
February	1st to 10th	Day	13% 16% 7% 12% 10% 6% 6% 4 4 4 18%	1487
	11th to 20th	Day	15% 19% 8% 13% 7% 3 5% 4 3 4 19%	1725
	21st to end	Day	13% 16% 6% 13% 6% 4 6% 4 5% 5% 22%	1480
March	1st to 10th	Day	15% 15% 7% 11% 7% 4 4 3 3 5% 26%	1797
	11th to 20th	Day	17% 16% 7% 7% 7% 3 4 4 3 5% 28%	1912
	21st to end	Day	17% 13% 6% 9% 7% 3 5% 3 5% 5% 27%	2275
April	1st to 10th	Day	23% 15% 5% 9% 5% 3 3 3 4 5% 25%	2160
	11th to 20th	Day	21% 12% 4 5% 4 3 3 4 3 5% 37%	2234
	21st to end	Day	25% 12% 3 7% 5% 2 4 4 4 6% 28%	2340
May	1st to 10th	Day	22% 11% 4 6% 5% 3 5% 3 4 5% 31%	2340
	11th to 20th	Day	22% 9% 4 6% 5% 3 4 4 6% 7% 31%	2467
	21st to end	Day	20% 7% 3 7% 7% 3 6% 5% 6% 7% 28%	2747
June	1st to 10th	Day	25% 8% 3 5% 6% 3 5% 5% 6% 8% 25%	2700
	11th to 20th	Day	19% 7% 3 5% 6% 3 6% 5% 5% 8% 33%	2700
	21st to end	Day	21% 9% 4 8% 7% 4 5% 5% 5% 6% 24%	2700
July	1st to 10th	Day	17% 6% 4 6% 7% 4 5% 6% 6% 8% 30%	2546
	11th to 20th	Day	15% 7% 3 7% 7% 4 6% 6% 7% 9% 29%	2520
	21st to end	Day	19% 8% 3 6% 6% 4 5% 6% 7% 8% 29%	2744
August	1st to 10th	Day	19% 7% 3 7% 7% 4 6% 7% 7% 8% 27%	2447
	11th to 20th	Day	17% 6% 3 7% 7% 4 6% 6% 5% 8% 31%	2304
	21st to end	Day	17% 8% 3 6% 5% 4 5% 4 5% 7% 36%	2485
September	1st to 10th	Day	17% 7% 2 6% 6% 3 5% 6% 5% 8% 35%	2155
	11th to 20th	Day	19% 7% 2 5% 4 2 3 4 5% 7% 41%	1980
	21st to end	Day	19% 8% 2 6% 4 2 4 5% 6% 9% 34%	1980
October	1st to 10th	Day	21% 10% 4 6% 5% 4 4 5% 6% 7% 30%	1980
	11th to 20th	Day	21% 12% 4 8% 7% 4 6% 4 4 5% 25%	1669
	21st to end	Day	26% 17% 5% 7% 6% 3 3 4 4 5% 20%	1782
November	1st to 10th	Day	20% 15% 5% 7% 6% 3 4 4 4 5% 27%	1671
	11th to 20th	Day	19% 15% 7% 11% 6% 3 4 3 4 5% 24%	1710
	21st to end	Day	20% 17% 5% 10% 7% 3 4 4 4 5% 20%	1432
December	1st to 10th	Day	22% 19% 7% 13% 6% 2 4 3 4 3 16%	1330
	11th to 20th	Day	20% 16% 7% 9% 8% 4 4 3 4 3 21%	1668
	21st to end	Day	23% 18% 6% 13% 7% 3 4 3 3 3 16%	2529
January	1st to 10th	Night	16% 17% 8% 14% 9% 4 5% 3 4 4 14%	2649
	11th to 20th	Night	15% 17% 8% 12% 10% 4 4 4 3 4 18%	2660
	21st to end	Night	11% 13% 7% 13% 9% 4 7% 5% 4 5% 23%	2868
February	1st to 10th	Night	12% 15% 6% 11% 10% 5% 7% 3 4 5% 21%	2471
	11th to 20th	Night	13% 16% 7% 14% 9% 5% 7% 4 3 4 20%	2120
	21st to end	Night	13% 16% 6% 10% 7% 3 4 4 3 4 28%	1776
March	1st to 10th	Night	14% 15% 7% 9% 7% 4 4 4 4 6% 27%	2150
	11th to 20th	Night	17% 14% 6% 8% 6% 3 5% 4 4 5% 29%	2047
	21st to end	Night	18% 12% 5% 8% 5% 3 5% 4 5% 5% 30%	2080
April	1st to 10th	Night	23% 14% 5% 7% 5% 2 3 4 5% 5% 27%	1800
	11th to 20th	Night	20% 10% 2 6% 6% 3 4 5% 4 6% 33%	1674
	21st to end	Night	22% 12% 4 7% 6% 4 4 4 4 5% 29%	1620
May	1st to 10th	Night	23% 9% 5% 7% 5% 2 4 4 5% 6% 31%	1620
	11th to 20th	Night	19% 8% 4 7% 6% 3 4 4 5% 5% 35%	1443
	21st to end	Night	20% 7% 3 5% 5% 3 4 5% 4 6% 36%	1526
June	1st to 10th	Night	23% 9% 4 7% 6% 3 5% 4 5% 6% 28%	1260
	11th to 20th	Night	19% 6% 3 6% 5% 3 4 5% 6% 7% 36%	1260
	21st to end	Night	19% 7% 3 8% 6% 3 5% 5% 6% 7% 33%	1260
July	1st to 10th	Night	16% 7% 3 5% 5% 3 6% 5% 6% 8% 36%	1409
	11th to 20th	Night	14% 6% 2 7% 6% 4 5% 6% 7% 9% 35%	1440
	21st to end	Night	15% 7% 3 7% 6% 3 6% 6% 5% 8% 35%	1574
August	1st to 10th	Night	15% 5% 2 5% 5% 3 5% 5% 7% 10% 39%	1472
	11th to 20th	Night	15% 7% 3 7% 5% 3 6% 6% 6% 8% 35%	1596
	21st to end	Night	14% 6% 3 6% 5% 3 5% 5% 5% 7% 42%	1867
September	1st to 10th	Night	16% 7% 3 5% 6% 3 4 4 6% 7% 38%	1804
	11th to 20th	Night	18% 7% 2 6% 4 2 3 4 4 6% 44%	1980
	21st to end	Night	17% 6% 3 5% 5% 2 4 4 5% 7% 42%	1980
October	1st to 10th	Night	20% 8% 2 6% 5% 2 4 4 5% 7% 37%	1980
	11th to 20th	Night	22% 10% 3 7% 7% 4 4 4 4 6% 29%	2288
	21st to end	Night	24% 15% 4 7% 5% 2 4 3 4 5% 26%	2574
November	1st to 10th	Night	20% 13% 4 6% 6% 3 4 4 4 6% 28%	2407
	11th to 20th	Night	19% 11% 7% 9% 6% 4 4 3 4 5% 28%	2470
	21st to end	Night	19% 18% 7% 9% 6% 3 4 3 3 5% 23%	2744
December	1st to 10th	Night	23% 17% 7% 10% 9% 4 4 4 3 4 15%	2850
	11th to 20th	Night	19% 17% 7% 13% 9% 4 4 4 3 4 16%	3531
	21st to end	Night	23% 20% 6% 9% 5% 2 3 3 3 3 22%	5131

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	76% 5% 6% 8% 4	1518
	11th to 20th	Day	70% 5% 6% 13% 5% 1	1520
	21st to end	Day	63% 5% 6% 16% 9% 1	1632
February	1st to 10th	Day	73% 4 5% 10% 7% 2	1487
	11th to 20th	Day	72% 3 8% 9% 6% 1	1734
	21st to end	Day	64% 5% 7% 15% 7% 2	1480
March	1st to 10th	Day	62% 4 8% 14% 10% 2	1800
	11th to 20th	Day	61% 4 8% 15% 11% 1	1912
	21st to end	Day	60% 5% 8% 16% 9% 2	2275
April	1st to 10th	Day	63% 4 9% 13% 9% 3	2160
	11th to 20th	Day	52% 4 9% 21% 13% 1	2234
	21st to end	Day	59% 4 8% 16% 10% 3	2340
May	1st to 10th	Day	56% 4 8% 18% 12% 2	2340
	11th to 20th	Day	54% 5% 11% 20% 10% 1	2471
	21st to end	Day	53% 7% 11% 18% 10% 1	2747
June	1st to 10th	Day	56% 6% 10% 20% 6% 1	2700
	11th to 20th	Day	50% 5% 11% 22% 10% 1	2700
	21st to end	Day	60% 6% 9% 17% 7%	2700
July	1st to 10th	Day	50% 7% 16% 20% 7%	2476
	11th to 20th	Day	49% 8% 15% 21% 7%	2445
	21st to end	Day	52% 7% 13% 21% 5% 1	2591
August	1st to 10th	Day	53% 8% 17% 19% 3	2433
	11th to 20th	Day	50% 6% 15% 19% 9%	2304
	21st to end	Day	48% 6% 13% 24% 9%	2485
September	1st to 10th	Day	47% 7% 15% 20% 11% 1	2155
	11th to 20th	Day	43% 5% 13% 27% 12%	1980
	21st to end	Day	46% 7% 13% 24% 10%	1980
October	1st to 10th	Day	54% 5% 11% 22% 8%	1980
	11th to 20th	Day	62% 5% 13% 17% 2	1669
	21st to end	Day	67% 4 8% 15% 5% 1	1782
November	1st to 10th	Day	61% 5% 11% 18% 6%	1671
	11th to 20th	Day	65% 4 10% 14% 6% 1	1710
	21st to end	Day	67% 6% 11% 13% 3	1432
December	1st to 10th	Day	75% 4 7% 10% 4	1330
	11th to 20th	Day	69% 5% 6% 13% 7%	1668
	21st to end	Day	74% 4 6% 9% 5% 2	2529
January	1st to 10th	Night	75% 6% 5% 9% 4	2649
	11th to 20th	Night	72% 6% 6% 10% 5% 1	2660
	21st to end	Night	64% 7% 7% 13% 7% 2	2868
February	1st to 10th	Night	68% 4 7% 13% 7% 1	2471
	11th to 20th	Night	71% 4 6% 11% 7% 1	2122
	21st to end	Night	62% 4 7% 15% 11% 1	1776
March	1st to 10th	Night	60% 5% 7% 17% 9% 1	2160
	11th to 20th	Night	58% 6% 9% 13% 13% 2	2048
	21st to end	Night	56% 5% 8% 20% 8% 3	2080
April	1st to 10th	Night	61% 4 6% 15% 12% 3	1800
	11th to 20th	Night	53% 5% 7% 22% 12% 2	1674
	21st to end	Night	58% 6% 8% 15% 11% 2	1620
May	1st to 10th	Night	54% 4 9% 17% 14% 1	1620
	11th to 20th	Night	51% 5% 9% 21% 13% 1	1444
	21st to end	Night	49% 6% 13% 18% 13% 1	1527
June	1st to 10th	Night	57% 5% 11% 19% 8%	1260
	11th to 20th	Night	47% 6% 10% 24% 11% 2	1260
	21st to end	Night	51% 7% 14% 19% 9%	1260
July	1st to 10th	Night	43% 9% 18% 22% 8%	1369
	11th to 20th	Night	44% 9% 17% 22% 9%	1392
	21st to end	Night	48% 7% 16% 21% 8%	1486
August	1st to 10th	Night	41% 9% 20% 26% 4	1462
	11th to 20th	Night	45% 8% 18% 22% 6% 1	1596
	21st to end	Night	41% 7% 14% 28% 9%	1867
September	1st to 10th	Night	44% 6% 14% 25% 9% 1	1804
	11th to 20th	Night	42% 5% 15% 28% 9% 1	1980
	21st to end	Night	42% 7% 13% 24% 13%	1980
October	1st to 10th	Night	48% 5% 11% 24% 12%	1980
	11th to 20th	Night	58% 5% 12% 20% 5%	2288
	21st to end	Night	61% 5% 11% 15% 7%	2574
November	1st to 10th	Night	58% 7% 11% 18% 6%	2407
	11th to 20th	Night	60% 5% 12% 14% 8% 1	2470
	21st to end	Night	66% 5% 10% 14% 4	2744
December	1st to 10th	Night	74% 5% 8% 10% 3	2850
	11th to 20th	Night	73% 6% 6% 11% 4	3532
	21st to end	Night	69% 3 8% 15% 6%	5131

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	28% 22% 33% 16% 2	180
	11th to 20th	Day	35% 22% 28% 10% 4	180
	21st to end	Day	23% 24% 35% 13% 3 1	188
February	1st to 10th	Day	38% 22% 28% 9% 4	207
	11th to 20th	Day	28% 27% 31% 12% 2	406
	21st to end	Day	26% 26% 29% 16% 3	346
March	1st to 10th	Day	28% 24% 30% 13% 5%	420
	11th to 20th	Day	32% 21% 26% 15% 5% 1	420
	21st to end	Day	32% 19% 25% 14% 7% 2	462
April	1st to 10th	Day	38% 18% 24% 13% 5% 2	420
	11th to 20th	Day	34% 19% 24% 15% 6% 2	412
	21st to end	Day	35% 19% 27% 13% 5% 2	420
May	1st to 10th	Day	34% 17% 29% 16% 3 1	423
	11th to 20th	Day	28% 16% 30% 19% 5% 2	447
	21st to end	Day	23% 21% 34% 15% 6% 1	507
June	1st to 10th	Day	30% 13% 29% 20% 7% 1	630
	11th to 20th	Day	23% 14% 26% 25% 11% 2	630
	21st to end	Day	25% 13% 30% 20% 11% 2	630
July	1st to 10th	Day	22% 11% 34% 24% 8% 1	471
	11th to 20th	Day	19% 12% 36% 21% 11% 1	444
	21st to end	Day	24% 12% 30% 25% 9% 1	488
August	1st to 10th	Day	20% 13% 30% 24% 10% 2	446
	11th to 20th	Day	24% 9% 26% 25% 14% 3	439
	21st to end	Day	25% 13% 25% 21% 10% 6%	495
September	1st to 10th	Day	20% 14% 29% 22% 11% 5%	450
	11th to 20th	Day	26% 11% 25% 20% 14% 5%	450
	21st to end	Day	24% 16% 22% 20% 12% 6%	450
October	1st to 10th	Day	26% 15% 23% 20% 13% 4	450
	11th to 20th	Day	34% 13% 24% 16% 11% 1	365
	21st to end	Day	39% 16% 24% 16% 5%	396
November	1st to 10th	Day	35% 14% 29% 19% 4	365
	11th to 20th	Day	27% 21% 26% 15% 9% 1	370
	21st to end	Day	34% 19% 26% 16% 4 1	251
December	1st to 10th	Day	35% 18% 23% 16% 7% 1	180
	11th to 20th	Day	39% 22% 21% 13% 3 1	180
	21st to end	Day	36% 23% 25% 12% 4 1	198
January	1st to 10th	Night	27% 21% 31% 18% 2	760
	11th to 20th	Night	29% 19% 33% 17% 3	760
	21st to end	Night	21% 17% 35% 22% 5%	820
February	1st to 10th	Night	23% 22% 33% 18% 4	720
	11th to 20th	Night	27% 20% 33% 17% 3	703
	21st to end	Night	27% 17% 31% 22% 3	592
March	1st to 10th	Night	26% 16% 35% 20% 3	720
	11th to 20th	Night	27% 18% 32% 17% 5% 1	720
	21st to end	Night	27% 16% 26% 23% 8% 1	792
April	1st to 10th	Night	34% 14% 28% 20% 5% 1	720
	11th to 20th	Night	27% 12% 29% 25% 7%	610
	21st to end	Night	30% 18% 26% 20% 6%	540
May	1st to 10th	Night	28% 11% 30% 23% 8% 1	540
	11th to 20th	Night	24% 11% 30% 30% 6%	382
	21st to end	Night	26% 7% 28% 30% 9%	389
June	1st to 10th	Night	29% 8% 23% 31% 8% 1	360
	11th to 20th	Night	23% 6% 24% 34% 13% 1	360
	21st to end	Night	20% 7% 31% 29% 12% 1	360
July	1st to 10th	Night	18% 9% 30% 31% 12% 1	350
	11th to 20th	Night	17% 4 24% 41% 14%	348
	21st to end	Night	18% 5% 23% 42% 11%	394
August	1st to 10th	Night	16% 5% 18% 40% 20%	398
	11th to 20th	Night	18% 6% 23% 35% 17% 1	532
	21st to end	Night	17% 8% 24% 33% 16% 2	679
September	1st to 10th	Night	19% 8% 27% 30% 13% 2	720
	11th to 20th	Night	24% 8% 21% 30% 15% 2	720
	21st to end	Night	23% 8% 28% 26% 15% 1	720
October	1st to 10th	Night	25% 10% 24% 31% 10%	720
	11th to 20th	Night	30% 12% 26% 22% 9% 1	720
	21st to end	Night	34% 14% 28% 19% 6%	792
November	1st to 10th	Night	31% 13% 25% 25% 6%	740
	11th to 20th	Night	28% 14% 28% 19% 9% 1	760
	21st to end	Night	31% 17% 29% 19% 5% 1	834
December	1st to 10th	Night	35% 16% 27% 17% 5%	850
	11th to 20th	Night	31% 20% 23% 19% 6%	850
	21st to end	Night	35% 19% 25% 17% 4	904

Page generated at 2024-01-24 09:37:31. Version ac07

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