Beauceville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beauceville clear sky chart from 2005-11-06 to 2026-05-02.

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	17% 11% 4 10% 6% 5% 5% 4 5% 6% 27%	131045
	Night	16% 13% 5% 11% 6% 5% 5% 4 5% 5% 26%	131452
Transparency	Day	58% 5% 11% 17% 8% 1	134500
	Night	60% 4 11% 16% 7% 1	136085
Seeing	Day	28% 17% 28% 18% 8% 2	17129
	Night	26% 14% 28% 24% 8% 1	25773

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% 16% 8% 17% 8% 7% 5% 4 4 4 14%	4661
	11th to 20th	Day	10% 18% 9% 22% 10% 5% 3 2 3 3 15%	4650
	21st to end	Day	5% 11% 7% 16% 8% 10% 7% 5% 5% 6% 19%	5124
February	1st to 10th	Day	11% 16% 5% 13% 10% 7% 4 4 4 5% 21%	1725
	11th to 20th	Day	12% 20% 7% 13% 6% 6% 5% 2 3 3 22%	2024
	21st to end	Day	12% 17% 5% 13% 7% 6% 4 3 4 5% 24%	1730
March	1st to 10th	Day	19% 17% 6% 12% 6% 5% 4 2 3 5% 23%	4576
	11th to 20th	Day	15% 17% 4 10% 5% 4 4 3 4 5% 27%	4902
	21st to end	Day	20% 16% 5% 10% 5% 4 3 2 4 4 28%	5862
April	1st to 10th	Day	21% 17% 3 10% 5% 3 3 3 4 5% 26%	2520
	11th to 20th	Day	20% 13% 3 7% 4 3 4 3 3 4 35%	2607
	21st to end	Day	24% 11% 3 7% 4 5% 4 3 5% 5% 29%	2730
May	1st to 10th	Day	26% 10% 3 8% 6% 5% 5% 3 4 6% 23%	5899
	11th to 20th	Day	23% 9% 3 7% 5% 4 6% 4 5% 7% 27%	6318
	21st to end	Day	20% 7% 3 8% 6% 5% 5% 4 6% 7% 28%	6995
June	1st to 10th	Day	23% 9% 3 7% 5% 4 5% 4 7% 8% 27%	3000
	11th to 20th	Day	19% 6% 3 7% 5% 5% 5% 4 7% 7% 33%	3000
	21st to end	Day	21% 11% 3 9% 5% 5% 5% 4 6% 5% 26%	3000
July	1st to 10th	Day	16% 7% 3 9% 7% 7% 7% 5% 7% 8% 24%	6412
	11th to 20th	Day	14% 6% 2 8% 5% 6% 6% 5% 7% 9% 33%	6360
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 6% 9% 40%	6926
August	1st to 10th	Day	16% 7% 2 8% 5% 6% 6% 5% 7% 8% 28%	4468
	11th to 20th	Day	18% 7% 3 8% 6% 6% 6% 4 6% 9% 27%	4175
	21st to end	Day	19% 8% 3 7% 4 5% 4 4 5% 7% 35%	4493
September	1st to 10th	Day	15% 7% 3 8% 4 5% 5% 4 5% 8% 37%	2398
	11th to 20th	Day	18% 6% 3 6% 4 3 4 3 5% 7% 43%	2200
	21st to end	Day	17% 9% 3 6% 3 4 4 4 7% 9% 35%	2200
October	1st to 10th	Day	19% 10% 3 6% 4 5% 4 4 5% 7% 33%	2200
	11th to 20th	Day	20% 12% 3 9% 6% 5% 5% 3 5% 5% 27%	1850
	21st to end	Day	24% 15% 5% 8% 6% 4 4 3 5% 5% 22%	1980
November	1st to 10th	Day	18% 17% 4 8% 5% 5% 4 3 4 5% 27%	1851
	11th to 20th	Day	19% 17% 7% 10% 5% 4 3 2 4 5% 24%	1890
	21st to end	Day	19% 19% 5% 12% 6% 4 4 3 4 5% 19%	1570
December	1st to 10th	Day	17% 16% 7% 14% 7% 5% 4 4 4 5% 17%	2350
	11th to 20th	Day	17% 15% 6% 12% 6% 4 3 3 4 5% 23%	2688
	21st to end	Day	17% 19% 6% 13% 5% 4 5% 3 5% 5% 19%	3711
January	1st to 10th	Night	12% 16% 8% 19% 8% 5% 4 3 4 5% 16%	8234
	11th to 20th	Night	9% 21% 9% 20% 10% 6% 4 3 3 3 13%	8235
	21st to end	Night	6% 12% 7% 14% 10% 9% 6% 6% 6% 5% 20%	9057
February	1st to 10th	Night	10% 15% 5% 13% 9% 6% 5% 3 4 5% 24%	2893
	11th to 20th	Night	11% 16% 7% 13% 8% 6% 5% 3 3 5% 21%	2479
	21st to end	Night	13% 17% 6% 11% 6% 4 4 3 4 5% 29%	2076
March	1st to 10th	Night	20% 16% 5% 11% 5% 4 5% 2 4 5% 23%	5484
	11th to 20th	Night	15% 15% 4 11% 6% 5% 5% 4 5% 5% 26%	5277
	21st to end	Night	18% 16% 5% 10% 5% 4 4 2 4 5% 27%	5308
April	1st to 10th	Night	21% 15% 4 8% 4 3 4 3 5% 4 28%	2100
	11th to 20th	Night	19% 12% 3 7% 5% 5% 4 3 5% 6% 32%	1961
	21st to end	Night	21% 11% 4 7% 5% 3 5% 4 4 5% 31%	1890
May	1st to 10th	Night	23% 10% 3 8% 5% 5% 5% 4 5% 6% 25%	4064
	11th to 20th	Night	24% 9% 2 7% 5% 4 4 3 4 6% 31%	3604
	21st to end	Night	19% 7% 2 6% 5% 4 4 4 5% 7% 36%	3865
June	1st to 10th	Night	21% 9% 3 7% 5% 5% 4 3 5% 6% 30%	1400
	11th to 20th	Night	17% 7% 3 6% 5% 5% 4 4 6% 7% 36%	1400
	21st to end	Night	18% 8% 3 7% 5% 5% 5% 4 6% 7% 32%	1400
July	1st to 10th	Night	15% 8% 3 8% 6% 5% 6% 4 7% 9% 30%	3545
	11th to 20th	Night	18% 6% 3 6% 4 4 4 3 5% 7% 38%	3600
	21st to end	Night	11% 6% 2 7% 5% 5% 4 5% 6% 8% 40%	3926
August	1st to 10th	Night	18% 7% 3 7% 5% 4 4 4 5% 7% 35%	2648
	11th to 20th	Night	15% 7% 3 9% 6% 6% 7% 4 5% 7% 31%	2872
	21st to end	Night	17% 7% 3 7% 4 4 6% 4 6% 6% 36%	3388
September	1st to 10th	Night	15% 6% 3 6% 5% 5% 5% 3 5% 7% 40%	2000
	11th to 20th	Night	16% 5% 2 6% 4 3 4 3 5% 6% 46%	2200
	21st to end	Night	16% 7% 2 6% 5% 4 5% 4 4 6% 41%	2200
October	1st to 10th	Night	17% 8% 3 6% 3 4 5% 3 5% 7% 39%	2200
	11th to 20th	Night	20% 9% 3 8% 6% 5% 5% 3 5% 6% 31%	2548
	21st to end	Night	21% 13% 4 9% 4 4 4 3 4 5% 28%	2860
November	1st to 10th	Night	19% 14% 4 8% 5% 4 4 3 5% 5% 28%	2667
	11th to 20th	Night	17% 13% 5% 9% 6% 5% 4 4 5% 5% 28%	2730
	21st to end	Night	18% 18% 6% 10% 6% 4 4 3 4 5% 22%	3042
December	1st to 10th	Night	15% 16% 8% 17% 10% 6% 4 3 4 4 13%	5060
	11th to 20th	Night	19% 17% 6% 15% 7% 4 4 3 4 4 17%	5741
	21st to end	Night	18% 18% 6% 10% 5% 4 4 3 5% 5% 22%	7498

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% 3 7% 11% 3	4662
	11th to 20th	Day	79% 2 5% 9% 5% 1	4680
	21st to end	Day	68% 5% 6% 11% 10%	5124
February	1st to 10th	Day	68% 4 6% 13% 7% 2	1725
	11th to 20th	Day	69% 4 8% 11% 7% 1	2033
	21st to end	Day	63% 4 9% 16% 7% 2	1730
March	1st to 10th	Day	67% 3 7% 10% 9% 3	4579
	11th to 20th	Day	59% 3 15% 13% 8% 1	4902
	21st to end	Day	62% 3 6% 15% 12% 2	5862
April	1st to 10th	Day	62% 4 9% 14% 9% 2	2520
	11th to 20th	Day	54% 4 8% 20% 12% 1	2607
	21st to end	Day	57% 4 9% 17% 11% 2	2730
May	1st to 10th	Day	63% 4 9% 15% 8% 1	5910
	11th to 20th	Day	55% 8% 14% 15% 6% 2	6322
	21st to end	Day	54% 6% 11% 16% 10% 2	6995
June	1st to 10th	Day	54% 7% 12% 20% 6% 1	3000
	11th to 20th	Day	48% 7% 13% 21% 10% 1	3000
	21st to end	Day	59% 8% 10% 16% 8%	3000
July	1st to 10th	Day	56% 5% 15% 18% 6%	6342
	11th to 20th	Day	47% 5% 17% 26% 5%	6285
	21st to end	Day	41% 5% 15% 31% 8%	6728
August	1st to 10th	Day	51% 7% 17% 20% 5%	4454
	11th to 20th	Day	54% 7% 17% 17% 5%	4214
	21st to end	Day	49% 6% 14% 20% 11% 1	4493
September	1st to 10th	Day	45% 8% 14% 23% 10% 1	2398
	11th to 20th	Day	41% 5% 13% 28% 12%	2200
	21st to end	Day	45% 8% 13% 24% 11%	2200
October	1st to 10th	Day	54% 4 12% 24% 5%	3590
	11th to 20th	Day	55% 4 14% 25% 2	2975
	21st to end	Day	56% 3 15% 18% 7%	3180
November	1st to 10th	Day	61% 5% 11% 17% 6%	1851
	11th to 20th	Day	66% 4 10% 13% 7% 1	1890
	21st to end	Day	69% 6% 10% 11% 3	1570
December	1st to 10th	Day	72% 3 10% 10% 5%	2350
	11th to 20th	Day	65% 4 8% 14% 9%	2688
	21st to end	Day	69% 4 7% 9% 10% 1	3711
January	1st to 10th	Night	74% 4 10% 9% 4	8234
	11th to 20th	Night	80% 3 6% 8% 3	8280
	21st to end	Night	67% 4 7% 11% 10% 1	9057
February	1st to 10th	Night	64% 5% 8% 14% 8% 1	2893
	11th to 20th	Night	68% 4 8% 12% 7% 1	2481
	21st to end	Night	60% 4 8% 16% 11% 1	2076
March	1st to 10th	Night	66% 4 8% 12% 9% 2	5494
	11th to 20th	Night	61% 4 16% 12% 7% 1	5278
	21st to end	Night	61% 3 6% 19% 10% 1	5308
April	1st to 10th	Night	59% 4 6% 16% 12% 2	2100
	11th to 20th	Night	54% 3 10% 20% 11% 2	1961
	21st to end	Night	56% 5% 9% 16% 12% 2	1890
May	1st to 10th	Night	59% 5% 11% 16% 8% 1	4070
	11th to 20th	Night	53% 6% 12% 21% 7%	3605
	21st to end	Night	48% 6% 16% 16% 14% 1	3866
June	1st to 10th	Night	55% 7% 10% 20% 8%	1400
	11th to 20th	Night	47% 7% 11% 22% 11% 2	1400
	21st to end	Night	52% 8% 13% 19% 9%	1400
July	1st to 10th	Night	50% 5% 20% 20% 5%	3505
	11th to 20th	Night	47% 4 20% 23% 5%	3552
	21st to end	Night	43% 5% 18% 27% 6%	3809
August	1st to 10th	Night	49% 6% 17% 23% 4	2638
	11th to 20th	Night	53% 7% 17% 17% 6% 1	2899
	21st to end	Night	47% 6% 14% 20% 13%	3388
September	1st to 10th	Night	42% 6% 15% 26% 9% 1	2000
	11th to 20th	Night	40% 5% 16% 30% 9%	2200
	21st to end	Night	43% 7% 13% 24% 13%	2200
October	1st to 10th	Night	48% 4 12% 26% 9%	3590
	11th to 20th	Night	55% 4 13% 25% 3	4162
	21st to end	Night	53% 4 16% 19% 9%	4610
November	1st to 10th	Night	59% 6% 13% 17% 5%	2667
	11th to 20th	Night	59% 5% 13% 13% 9% 1	2730
	21st to end	Night	67% 5% 11% 13% 4	3042
December	1st to 10th	Night	78% 3 8% 9% 2	5060
	11th to 20th	Night	72% 3 7% 14% 4	5742
	21st to end	Night	66% 4 7% 15% 8%	7498

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	30% 19% 36% 14% 2	220
	11th to 20th	Day	35% 23% 28% 10% 3	220
	21st to end	Day	22% 25% 36% 14% 4	242
February	1st to 10th	Day	30% 25% 27% 9% 8% 1	265
	11th to 20th	Day	28% 25% 31% 13% 3	524
	21st to end	Day	26% 25% 28% 17% 3	446
March	1st to 10th	Day	31% 24% 28% 13% 4	540
	11th to 20th	Day	30% 24% 28% 13% 4 1	540
	21st to end	Day	36% 20% 24% 12% 6% 2	594
April	1st to 10th	Day	39% 17% 26% 11% 5% 1	540
	11th to 20th	Day	37% 20% 23% 14% 5% 1	532
	21st to end	Day	34% 20% 27% 12% 5% 2	540
May	1st to 10th	Day	34% 18% 29% 15% 3 1	507
	11th to 20th	Day	28% 16% 28% 20% 6% 2	527
	21st to end	Day	22% 22% 36% 14% 6% 1	593
June	1st to 10th	Day	28% 14% 29% 22% 7% 1	730
	11th to 20th	Day	23% 15% 27% 24% 11% 1	730
	21st to end	Day	26% 13% 30% 20% 9% 1	730
July	1st to 10th	Day	21% 12% 35% 23% 9% 1	551
	11th to 20th	Day	20% 12% 38% 19% 9% 2	524
	21st to end	Day	22% 10% 35% 23% 9% 1	576
August	1st to 10th	Day	18% 11% 30% 26% 12% 2	526
	11th to 20th	Day	21% 9% 27% 24% 16% 3	519
	21st to end	Day	25% 12% 26% 20% 13% 5%	583
September	1st to 10th	Day	19% 14% 31% 21% 11% 5%	530
	11th to 20th	Day	22% 11% 25% 19% 17% 7%	530
	21st to end	Day	22% 16% 24% 21% 12% 6%	530
October	1st to 10th	Day	24% 16% 23% 21% 12% 3	530
	11th to 20th	Day	32% 14% 26% 15% 11% 1	428
	21st to end	Day	36% 17% 25% 16% 5%	462
November	1st to 10th	Day	37% 14% 28% 17% 4	425
	11th to 20th	Day	29% 20% 25% 17% 8%	430
	21st to end	Day	36% 20% 27% 13% 2 1	283
December	1st to 10th	Day	34% 16% 28% 17% 4 1	220
	11th to 20th	Day	38% 22% 24% 12% 3 1	220
	21st to end	Day	34% 20% 26% 14% 4 2	242
January	1st to 10th	Night	26% 21% 31% 18% 3	840
	11th to 20th	Night	28% 19% 32% 17% 4	840
	21st to end	Night	20% 15% 35% 23% 5% 1	924
February	1st to 10th	Night	20% 21% 34% 19% 6%	840
	11th to 20th	Night	25% 21% 32% 18% 3	823
	21st to end	Night	26% 17% 32% 22% 3	692
March	1st to 10th	Night	25% 19% 33% 20% 3	840
	11th to 20th	Night	28% 19% 31% 17% 4	840
	21st to end	Night	26% 17% 28% 22% 6% 1	924
April	1st to 10th	Night	34% 15% 28% 18% 5%	840
	11th to 20th	Night	29% 13% 28% 24% 6%	717
	21st to end	Night	29% 17% 29% 19% 6%	630
May	1st to 10th	Night	28% 12% 29% 24% 7%	604
	11th to 20th	Night	23% 9% 30% 30% 6% 1	410
	21st to end	Night	24% 8% 30% 29% 9%	433
June	1st to 10th	Night	26% 8% 27% 32% 8% 1	400
	11th to 20th	Night	21% 9% 23% 34% 14%	400
	21st to end	Night	21% 8% 29% 30% 12%	400
July	1st to 10th	Night	17% 6% 33% 32% 11% 1	390
	11th to 20th	Night	19% 3 24% 40% 13%	388
	21st to end	Night	16% 5% 24% 43% 12%	438
August	1st to 10th	Night	17% 3 19% 41% 20%	434
	11th to 20th	Night	17% 5% 25% 32% 19% 1	592
	21st to end	Night	16% 7% 27% 32% 17% 2	760
September	1st to 10th	Night	19% 8% 28% 30% 14% 2	800
	11th to 20th	Night	21% 8% 19% 30% 20% 2	800
	21st to end	Night	22% 8% 28% 25% 16% 1	800
October	1st to 10th	Night	23% 10% 25% 29% 13%	800
	11th to 20th	Night	29% 12% 26% 23% 10% 1	800
	21st to end	Night	32% 16% 26% 21% 6%	880
November	1st to 10th	Night	34% 13% 25% 22% 6%	820
	11th to 20th	Night	28% 15% 28% 20% 9% 1	840
	21st to end	Night	32% 17% 28% 18% 5% 1	930
December	1st to 10th	Night	31% 18% 27% 20% 5%	950
	11th to 20th	Night	30% 20% 24% 19% 6%	950
	21st to end	Night	33% 19% 25% 18% 5% 1	1004

Page generated at 2026-04-29 02:21:45. Version ac07

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