Antigonish
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Antigonish clear sky chart from 2005-11-06 to 2026-04-02.

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% 12% 5% 10% 6% 5% 5% 4 5% 6% 26%	131795
	Night	17% 12% 4 11% 6% 5% 5% 4 5% 6% 25%	130272
Transparency	Day	57% 7% 12% 17% 7% 1	135304
	Night	57% 7% 12% 16% 7% 1	134857
Seeing	Day	26% 18% 30% 19% 6% 1	19424
	Night	25% 17% 31% 21% 5%	27113

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	10% 15% 8% 21% 8% 6% 6% 4 4 5% 14%	4690
	11th to 20th	Day	15% 15% 11% 16% 6% 6% 4 3 4 4 15%	4681
	21st to end	Day	12% 11% 5% 12% 7% 6% 8% 5% 6% 5% 24%	5531
February	1st to 10th	Day	16% 14% 5% 13% 8% 7% 4 3 4 4 20%	1890
	11th to 20th	Day	13% 16% 6% 11% 8% 7% 4 3 4 5% 23%	1843
	21st to end	Day	10% 16% 6% 9% 7% 5% 6% 4 5% 6% 26%	1671
March	1st to 10th	Day	20% 14% 4 10% 7% 6% 4 3 4 4 24%	4733
	11th to 20th	Day	10% 18% 7% 11% 7% 5% 5% 3 5% 6% 22%	5090
	21st to end	Day	21% 19% 7% 13% 6% 4 4 3 4 4 15%	5774
April	1st to 10th	Day	19% 15% 6% 9% 5% 4 4 3 5% 5% 24%	2412
	11th to 20th	Day	20% 14% 4 7% 5% 4 3 3 4 7% 29%	2374
	21st to end	Day	22% 16% 4 8% 4 4 3 4 5% 5% 26%	2568
May	1st to 10th	Day	25% 19% 3 7% 4 4 3 3 5% 6% 21%	6344
	11th to 20th	Day	20% 12% 3 7% 4 4 4 4 6% 6% 30%	6318
	21st to end	Day	18% 11% 3 7% 5% 5% 5% 4 6% 7% 30%	6948
June	1st to 10th	Day	27% 12% 3 7% 5% 4 4 4 5% 7% 23%	2800
	11th to 20th	Day	21% 9% 2 7% 5% 4 4 3 5% 7% 33%	2800
	21st to end	Day	23% 11% 4 9% 6% 4 4 4 5% 6% 25%	2800
July	1st to 10th	Day	17% 9% 3 8% 6% 5% 6% 5% 7% 8% 26%	6360
	11th to 20th	Day	12% 6% 3 7% 6% 5% 6% 4 7% 9% 36%	6360
	21st to end	Day	12% 6% 2 7% 5% 5% 6% 4 8% 9% 37%	6927
August	1st to 10th	Day	16% 9% 3 8% 5% 6% 5% 5% 6% 7% 29%	4377
	11th to 20th	Day	15% 9% 3 8% 5% 5% 5% 4 7% 7% 32%	4175
	21st to end	Day	11% 6% 3 6% 4 5% 6% 4 6% 7% 42%	4358
September	1st to 10th	Day	16% 7% 3 7% 5% 4 4 4 5% 7% 37%	2400
	11th to 20th	Day	18% 9% 3 6% 4 4 4 3 6% 7% 35%	2400
	21st to end	Day	18% 8% 3 6% 5% 5% 5% 4 6% 7% 36%	2107
October	1st to 10th	Day	18% 9% 2 9% 5% 5% 5% 5% 5% 7% 31%	2000
	11th to 20th	Day	20% 10% 3 10% 5% 5% 4 4 5% 8% 25%	2000
	21st to end	Day	21% 14% 4 10% 6% 5% 4 3 4 7% 22%	2092
November	1st to 10th	Day	20% 14% 5% 10% 6% 4 4 4 6% 6% 22%	1776
	11th to 20th	Day	19% 20% 6% 11% 7% 4 4 4 4 5% 17%	1680
	21st to end	Day	15% 19% 7% 13% 6% 6% 5% 4 5% 4 16%	1680
December	1st to 10th	Day	14% 15% 6% 14% 7% 7% 6% 3 4 5% 18%	2690
	11th to 20th	Day	24% 16% 5% 16% 6% 6% 4 2 4 4 13%	3076
	21st to end	Day	18% 12% 10% 19% 6% 5% 4 4 4 4 14%	4070
January	1st to 10th	Night	12% 14% 7% 19% 8% 6% 5% 4 5% 5% 14%	8234
	11th to 20th	Night	18% 14% 7% 16% 7% 6% 5% 3 4 4 16%	8234
	21st to end	Night	9% 10% 5% 15% 8% 7% 9% 5% 6% 5% 20%	8657
February	1st to 10th	Night	18% 12% 5% 14% 8% 5% 5% 3 5% 4 21%	2730
	11th to 20th	Night	14% 14% 5% 11% 9% 7% 6% 5% 4 5% 20%	2663
	21st to end	Night	11% 15% 5% 13% 7% 5% 5% 3 5% 5% 26%	2134
March	1st to 10th	Night	20% 15% 5% 10% 7% 5% 4 3 4 5% 21%	5310
	11th to 20th	Night	18% 15% 6% 8% 6% 5% 4 3 5% 6% 25%	5089
	21st to end	Night	25% 16% 5% 12% 5% 4 3 3 3 4 20%	5400
April	1st to 10th	Night	21% 15% 4 7% 6% 5% 5% 3 4 6% 24%	2011
	11th to 20th	Night	18% 13% 3 8% 5% 4 4 3 5% 6% 30%	1976
	21st to end	Night	22% 13% 4 7% 5% 4 5% 3 4 5% 27%	1830
May	1st to 10th	Night	26% 21% 3 6% 4 4 3 3 4 6% 19%	3615
	11th to 20th	Night	18% 14% 4 7% 4 4 5% 4 6% 6% 29%	3596
	21st to end	Night	14% 12% 4 8% 5% 5% 5% 4 6% 7% 30%	3948
June	1st to 10th	Night	26% 9% 3 8% 5% 4 5% 2 5% 6% 26%	1600
	11th to 20th	Night	21% 8% 2 6% 5% 4 4 3 5% 8% 35%	1600
	21st to end	Night	22% 9% 3 8% 6% 4 5% 4 5% 8% 28%	1600
July	1st to 10th	Night	14% 8% 4 10% 6% 7% 6% 5% 8% 9% 24%	3619
	11th to 20th	Night	12% 8% 3 6% 4 4 5% 4 6% 10% 39%	3620
	21st to end	Night	15% 7% 3 7% 5% 4 5% 4 7% 8% 36%	3948
August	1st to 10th	Night	13% 8% 3 9% 6% 6% 5% 4 6% 7% 33%	2773
	11th to 20th	Night	13% 7% 3 7% 5% 5% 5% 4 6% 9% 35%	2872
	21st to end	Night	12% 6% 2 6% 4 4 4 4 7% 9% 42%	3539
September	1st to 10th	Night	15% 7% 3 7% 5% 4 5% 4 6% 8% 38%	2000
	11th to 20th	Night	17% 8% 2 6% 4 4 3 3 6% 8% 39%	2000
	21st to end	Night	18% 8% 2 6% 4 4 4 4 5% 7% 38%	2289
October	1st to 10th	Night	19% 8% 2 7% 5% 4 4 4 6% 7% 36%	2400
	11th to 20th	Night	19% 9% 3 8% 5% 4 4 3 5% 8% 31%	2400
	21st to end	Night	24% 13% 4 8% 6% 4 5% 3 3 5% 25%	2746
November	1st to 10th	Night	17% 13% 4 10% 6% 5% 5% 4 5% 6% 23%	2736
	11th to 20th	Night	19% 16% 5% 11% 6% 5% 5% 4 5% 5% 19%	2940
	21st to end	Night	20% 15% 5% 10% 7% 5% 5% 4 5% 6% 17%	2940
December	1st to 10th	Night	15% 12% 5% 13% 7% 6% 6% 3 5% 5% 22%	4720
	11th to 20th	Night	23% 13% 4 12% 7% 6% 5% 3 4 5% 19%	5353
	21st to end	Night	22% 14% 5% 14% 6% 5% 4 3 4 5% 17%	7150

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	73% 6% 10% 8% 3	4691
	11th to 20th	Day	69% 7% 11% 9% 4	4710
	21st to end	Day	55% 7% 8% 15% 13% 2	5531
February	1st to 10th	Day	66% 5% 11% 11% 7%	1890
	11th to 20th	Day	63% 6% 11% 13% 6%	1851
	21st to end	Day	58% 5% 11% 15% 9% 2	1671
March	1st to 10th	Day	62% 5% 8% 13% 11% 1	4737
	11th to 20th	Day	61% 7% 15% 12% 4 1	5090
	21st to end	Day	72% 4 8% 11% 4 1	5774
April	1st to 10th	Day	62% 6% 8% 12% 10% 2	2412
	11th to 20th	Day	57% 4 10% 17% 11% 1	2374
	21st to end	Day	60% 7% 10% 14% 8% 1	2568
May	1st to 10th	Day	62% 7% 10% 16% 5% 1	6356
	11th to 20th	Day	53% 8% 12% 20% 7%	6322
	21st to end	Day	50% 10% 12% 20% 9%	6948
June	1st to 10th	Day	60% 7% 11% 17% 5% 1	2800
	11th to 20th	Day	51% 8% 11% 20% 10% 1	2800
	21st to end	Day	60% 8% 8% 14% 9% 1	2800
July	1st to 10th	Day	54% 7% 15% 16% 8%	6290
	11th to 20th	Day	43% 8% 16% 24% 8%	6284
	21st to end	Day	43% 8% 17% 25% 7%	6730
August	1st to 10th	Day	54% 8% 12% 19% 7%	4363
	11th to 20th	Day	49% 8% 13% 23% 6%	4214
	21st to end	Day	39% 6% 12% 29% 13%	4358
September	1st to 10th	Day	45% 7% 13% 23% 11% 1	2400
	11th to 20th	Day	48% 7% 11% 22% 12% 1	2400
	21st to end	Day	46% 7% 11% 23% 12%	2107
October	1st to 10th	Day	51% 8% 13% 19% 8%	3260
	11th to 20th	Day	48% 7% 13% 21% 11%	3240
	21st to end	Day	52% 7% 15% 18% 7% 1	3362
November	1st to 10th	Day	61% 7% 12% 14% 5%	1776
	11th to 20th	Day	68% 6% 12% 10% 5%	1680
	21st to end	Day	66% 8% 15% 8% 4	1680
December	1st to 10th	Day	64% 7% 9% 16% 5%	2690
	11th to 20th	Day	72% 6% 10% 5% 7%	3075
	21st to end	Day	69% 8% 12% 8% 3	4070
January	1st to 10th	Night	71% 6% 11% 9% 3 1	8234
	11th to 20th	Night	68% 7% 11% 10% 4	8280
	21st to end	Night	58% 9% 9% 13% 10% 1	8657
February	1st to 10th	Night	65% 6% 10% 11% 7% 1	2730
	11th to 20th	Night	65% 6% 11% 12% 5% 1	2666
	21st to end	Night	59% 4 10% 17% 9% 1	2134
March	1st to 10th	Night	63% 6% 7% 13% 10% 1	5319
	11th to 20th	Night	59% 5% 14% 14% 7% 1	5090
	21st to end	Night	68% 4 7% 14% 6% 1	5400
April	1st to 10th	Night	61% 6% 10% 12% 10% 2	2011
	11th to 20th	Night	54% 6% 9% 19% 11% 2	1976
	21st to end	Night	57% 6% 10% 15% 11% 1	1830
May	1st to 10th	Night	67% 6% 7% 13% 8%	3620
	11th to 20th	Night	54% 7% 11% 21% 7% 1	3597
	21st to end	Night	49% 11% 13% 23% 4	3949
June	1st to 10th	Night	58% 8% 9% 19% 7%	1600
	11th to 20th	Night	48% 7% 12% 19% 14% 1	1600
	21st to end	Night	54% 10% 10% 16% 9% 1	1600
July	1st to 10th	Night	54% 7% 15% 18% 6% 1	3581
	11th to 20th	Night	40% 7% 15% 25% 11% 1	3572
	21st to end	Night	46% 7% 16% 24% 7%	3831
August	1st to 10th	Night	49% 8% 15% 23% 5%	2762
	11th to 20th	Night	45% 10% 16% 25% 5%	2899
	21st to end	Night	35% 9% 17% 28% 11%	3538
September	1st to 10th	Night	42% 7% 13% 26% 11%	2000
	11th to 20th	Night	41% 7% 14% 27% 11% 1	2000
	21st to end	Night	45% 7% 12% 26% 10% 1	2289
October	1st to 10th	Night	49% 7% 15% 20% 10%	3920
	11th to 20th	Night	43% 7% 13% 26% 10%	3899
	21st to end	Night	50% 6% 14% 20% 8% 1	4432
November	1st to 10th	Night	59% 9% 13% 14% 5%	2736
	11th to 20th	Night	63% 8% 13% 11% 5%	2940
	21st to end	Night	64% 8% 15% 10% 3	2940
December	1st to 10th	Night	58% 7% 12% 18% 6%	4720
	11th to 20th	Night	64% 6% 10% 12% 6% 2	5355
	21st to end	Night	68% 6% 13% 11% 3	7150

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% 23% 32% 13% 2	430
	11th to 20th	Day	30% 25% 26% 14% 5%	430
	21st to end	Day	25% 23% 35% 15% 2	473
February	1st to 10th	Day	31% 23% 30% 14% 2	430
	11th to 20th	Day	27% 31% 27% 15% 1	426
	21st to end	Day	24% 22% 34% 16% 4	355
March	1st to 10th	Day	26% 23% 34% 15% 2	466
	11th to 20th	Day	22% 29% 31% 13% 4 1	540
	21st to end	Day	33% 25% 25% 14% 3 1	594
April	1st to 10th	Day	33% 27% 26% 11% 2	504
	11th to 20th	Day	31% 23% 30% 12% 3	492
	21st to end	Day	28% 21% 29% 17% 4 1	500
May	1st to 10th	Day	34% 17% 28% 15% 3 2	702
	11th to 20th	Day	24% 12% 33% 22% 8% 1	724
	21st to end	Day	24% 15% 35% 21% 5% 1	790
June	1st to 10th	Day	33% 13% 29% 18% 7% 1	730
	11th to 20th	Day	22% 14% 34% 23% 5% 1	730
	21st to end	Day	26% 13% 28% 23% 8% 1	730
July	1st to 10th	Day	19% 9% 35% 29% 7% 1	720
	11th to 20th	Day	16% 8% 34% 31% 10% 1	718
	21st to end	Day	19% 10% 29% 30% 10% 1	795
August	1st to 10th	Day	16% 7% 31% 32% 10% 3	616
	11th to 20th	Day	18% 10% 33% 26% 11% 3	519
	21st to end	Day	17% 13% 30% 26% 12% 2	583
September	1st to 10th	Day	17% 15% 34% 26% 7% 2	530
	11th to 20th	Day	25% 13% 28% 23% 8% 2	530
	21st to end	Day	22% 16% 31% 19% 9% 3	447
October	1st to 10th	Day	23% 13% 29% 28% 5% 2	420
	11th to 20th	Day	25% 20% 28% 16% 9% 2	420
	21st to end	Day	27% 20% 31% 16% 5%	462
November	1st to 10th	Day	28% 24% 28% 17% 3 1	425
	11th to 20th	Day	36% 24% 24% 13% 3	430
	21st to end	Day	31% 26% 27% 13% 3 1	430
December	1st to 10th	Day	31% 24% 29% 13% 3	430
	11th to 20th	Day	36% 25% 28% 10% 1	430
	21st to end	Day	25% 29% 30% 12% 2 1	473
January	1st to 10th	Night	27% 24% 33% 14% 2	950
	11th to 20th	Night	27% 23% 32% 15% 3	950
	21st to end	Night	23% 25% 32% 16% 3	971
February	1st to 10th	Night	29% 18% 32% 19% 3	840
	11th to 20th	Night	25% 28% 29% 16% 2	823
	21st to end	Night	21% 21% 34% 20% 5%	692
March	1st to 10th	Night	26% 19% 33% 20% 3	840
	11th to 20th	Night	23% 20% 30% 21% 6% 1	840
	21st to end	Night	29% 18% 30% 19% 3	840
April	1st to 10th	Night	29% 20% 30% 18% 2	604
	11th to 20th	Night	25% 19% 32% 19% 4 1	594
	21st to end	Night	30% 14% 29% 22% 5%	600
May	1st to 10th	Night	33% 14% 27% 19% 7% 1	600
	11th to 20th	Night	26% 11% 31% 24% 7% 1	592
	21st to end	Night	21% 14% 39% 21% 4	649
June	1st to 10th	Night	30% 9% 33% 23% 6%	600
	11th to 20th	Night	26% 9% 34% 27% 4 1	600
	21st to end	Night	24% 12% 30% 27% 6%	600
July	1st to 10th	Night	18% 7% 34% 34% 7% 1	586
	11th to 20th	Night	15% 6% 35% 35% 9% 1	582
	21st to end	Night	18% 7% 29% 36% 9%	656
August	1st to 10th	Night	15% 6% 29% 38% 12%	598
	11th to 20th	Night	19% 6% 28% 33% 12% 1	592
	21st to end	Night	16% 9% 28% 38% 10%	660
September	1st to 10th	Night	17% 9% 33% 32% 9% 1	600
	11th to 20th	Night	21% 13% 27% 28% 12%	600
	21st to end	Night	23% 12% 32% 26% 6% 1	740
October	1st to 10th	Night	22% 13% 31% 25% 9% 1	800
	11th to 20th	Night	22% 16% 32% 22% 7% 1	800
	21st to end	Night	30% 22% 29% 16% 4	939
November	1st to 10th	Night	28% 22% 29% 15% 4 1	930
	11th to 20th	Night	29% 24% 27% 14% 5%	950
	21st to end	Night	31% 23% 28% 15% 3	950
December	1st to 10th	Night	31% 22% 30% 13% 4	950
	11th to 20th	Night	34% 25% 29% 10% 2	950
	21st to end	Night	29% 25% 30% 13% 3 1	1045

Page generated at 2026-03-30 03:18:42. Version ac07

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