Guysborough
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Guysborough 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	19% 11% 4 9% 6% 5% 5% 4 5% 6% 27%	131759
	Night	19% 12% 4 9% 5% 5% 4 3 5% 6% 27%	130335
Transparency	Day	56% 6% 11% 17% 8% 1	135256
	Night	56% 6% 10% 18% 9% 1	134933
Seeing	Day	27% 21% 31% 15% 4 1	19441
	Night	27% 19% 31% 18% 5%	27081

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	11% 17% 8% 18% 7% 6% 5% 3 4 5% 16%	4690
	11th to 20th	Day	16% 13% 9% 12% 6% 6% 5% 4 5% 4 19%	4681
	21st to end	Day	13% 11% 4 9% 5% 4 4 4 6% 7% 33%	5478
February	1st to 10th	Day	19% 12% 4 12% 8% 5% 4 3 5% 5% 23%	1890
	11th to 20th	Day	17% 12% 5% 11% 6% 7% 5% 4 6% 6% 23%	1843
	21st to end	Day	13% 13% 6% 9% 7% 4 5% 4 4 6% 28%	1699
March	1st to 10th	Day	20% 12% 4 10% 7% 6% 5% 3 4 4 25%	4666
	11th to 20th	Day	12% 15% 6% 12% 7% 5% 5% 4 5% 6% 22%	5090
	21st to end	Day	25% 16% 4 11% 6% 5% 4 3 4 4 17%	5821
April	1st to 10th	Day	24% 15% 4 8% 5% 4 4 3 4 5% 25%	2412
	11th to 20th	Day	23% 12% 3 7% 4 4 4 3 4 6% 30%	2374
	21st to end	Day	22% 14% 3 7% 6% 3 3 4 5% 6% 27%	2547
May	1st to 10th	Day	24% 14% 4 9% 5% 4 4 4 5% 5% 22%	6345
	11th to 20th	Day	21% 13% 3 7% 4 4 4 3 5% 6% 29%	6318
	21st to end	Day	19% 11% 3 7% 4 4 4 3 5% 7% 30%	6948
June	1st to 10th	Day	27% 10% 3 7% 4 5% 5% 5% 5% 7% 23%	2800
	11th to 20th	Day	20% 9% 3 8% 6% 5% 4 4 6% 6% 30%	2800
	21st to end	Day	27% 11% 4 9% 5% 4 4 3 5% 6% 23%	2800
July	1st to 10th	Day	18% 10% 3 9% 6% 6% 6% 5% 6% 7% 24%	6360
	11th to 20th	Day	14% 6% 2 7% 6% 6% 6% 5% 8% 9% 30%	6360
	21st to end	Day	14% 7% 2 7% 5% 5% 5% 4 7% 9% 35%	6927
August	1st to 10th	Day	17% 10% 4 9% 6% 6% 5% 4 5% 7% 27%	4414
	11th to 20th	Day	18% 8% 3 8% 5% 5% 5% 4 7% 8% 28%	4175
	21st to end	Day	11% 7% 3 7% 5% 4 5% 4 5% 8% 42%	4317
September	1st to 10th	Day	18% 7% 2 7% 5% 5% 5% 3 6% 7% 36%	2400
	11th to 20th	Day	19% 8% 2 7% 4 4 4 4 5% 7% 35%	2400
	21st to end	Day	19% 7% 3 6% 5% 5% 4 3 4 8% 36%	2120
October	1st to 10th	Day	18% 9% 3 7% 5% 5% 5% 4 5% 7% 32%	2000
	11th to 20th	Day	21% 8% 3 8% 5% 5% 5% 5% 7% 8% 27%	2000
	21st to end	Day	22% 11% 4 8% 6% 4 5% 4 5% 6% 24%	2073
November	1st to 10th	Day	23% 13% 3 6% 5% 4 5% 3 4 7% 26%	1815
	11th to 20th	Day	24% 15% 3 10% 5% 5% 4 3 4 7% 20%	1680
	21st to end	Day	15% 16% 4 8% 6% 6% 5% 4 7% 7% 23%	1680
December	1st to 10th	Day	15% 15% 5% 10% 5% 5% 5% 4 5% 5% 26%	2690
	11th to 20th	Day	28% 11% 4 9% 5% 5% 4 3 4 5% 21%	3076
	21st to end	Day	20% 11% 8% 13% 6% 4 4 4 6% 6% 18%	4070
January	1st to 10th	Night	14% 16% 6% 14% 6% 5% 5% 3 5% 5% 20%	8234
	11th to 20th	Night	20% 13% 7% 14% 6% 5% 5% 3 4 4 19%	8234
	21st to end	Night	11% 10% 4 12% 6% 5% 7% 4 7% 7% 28%	8716
February	1st to 10th	Night	19% 12% 5% 12% 5% 6% 4 4 5% 5% 23%	2730
	11th to 20th	Night	16% 12% 6% 10% 6% 5% 5% 4 5% 7% 24%	2663
	21st to end	Night	12% 13% 7% 10% 5% 5% 5% 4 5% 5% 28%	2106
March	1st to 10th	Night	22% 13% 4 9% 6% 5% 5% 4 4 5% 23%	5392
	11th to 20th	Night	19% 11% 5% 9% 6% 5% 5% 4 4 6% 26%	5089
	21st to end	Night	29% 15% 5% 10% 5% 3 3 2 3 3 21%	5353
April	1st to 10th	Night	25% 13% 4 7% 4 5% 4 3 4 5% 26%	2011
	11th to 20th	Night	21% 11% 2 7% 4 4 5% 5% 6% 6% 30%	1976
	21st to end	Night	25% 11% 3 7% 5% 4 4 3 4 5% 29%	1848
May	1st to 10th	Night	25% 13% 3 10% 7% 5% 5% 4 4 5% 19%	3615
	11th to 20th	Night	22% 16% 3 7% 4 4 3 3 5% 6% 28%	3596
	21st to end	Night	16% 13% 3 8% 6% 5% 4 4 6% 7% 28%	3948
June	1st to 10th	Night	28% 11% 3 8% 4 4 4 3 4 5% 26%	1600
	11th to 20th	Night	22% 10% 3 6% 4 4 4 3 5% 8% 32%	1600
	21st to end	Night	27% 10% 3 8% 5% 3 4 3 5% 8% 23%	1600
July	1st to 10th	Night	17% 10% 4 10% 6% 6% 5% 4 7% 8% 22%	3619
	11th to 20th	Night	16% 11% 4 8% 4 5% 4 4 5% 7% 34%	3620
	21st to end	Night	17% 9% 3 7% 5% 4 5% 4 6% 8% 33%	3948
August	1st to 10th	Night	15% 9% 4 10% 7% 6% 4 4 4 6% 31%	2738
	11th to 20th	Night	16% 9% 4 8% 5% 5% 5% 3 7% 7% 30%	2872
	21st to end	Night	13% 6% 2 5% 4 4 4 3 5% 7% 46%	3581
September	1st to 10th	Night	17% 7% 3 5% 4 4 5% 4 6% 8% 38%	2000
	11th to 20th	Night	17% 7% 2 6% 4 5% 3 3 5% 7% 41%	2000
	21st to end	Night	20% 8% 4 7% 4 4 3 2 4 6% 38%	2278
October	1st to 10th	Night	19% 7% 2 6% 4 3 4 3 5% 8% 38%	2400
	11th to 20th	Night	21% 7% 3 7% 5% 4 5% 4 5% 6% 34%	2400
	21st to end	Night	24% 11% 3 8% 5% 4 4 3 5% 6% 27%	2765
November	1st to 10th	Night	20% 12% 3 8% 5% 5% 5% 3 6% 7% 26%	2700
	11th to 20th	Night	21% 14% 3 8% 5% 4 5% 5% 5% 6% 25%	2940
	21st to end	Night	20% 14% 3 9% 6% 5% 4 4 6% 5% 24%	2940
December	1st to 10th	Night	17% 11% 4 9% 5% 4 4 3 5% 6% 32%	4720
	11th to 20th	Night	25% 11% 4 9% 5% 4 4 3 4 5% 26%	5353
	21st to end	Night	24% 12% 6% 11% 4 4 4 3 4 5% 23%	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	68% 5% 9% 12% 6%	4691
	11th to 20th	Day	65% 5% 11% 13% 6%	4710
	21st to end	Day	50% 5% 5% 18% 18% 3	5478
February	1st to 10th	Day	63% 4 9% 12% 10% 1	1890
	11th to 20th	Day	61% 6% 9% 16% 8%	1851
	21st to end	Day	56% 5% 9% 17% 10% 3	1699
March	1st to 10th	Day	62% 4 8% 14% 12% 1	4670
	11th to 20th	Day	62% 6% 13% 14% 4 1	5090
	21st to end	Day	70% 5% 7% 13% 5% 1	5821
April	1st to 10th	Day	62% 5% 8% 13% 10% 3	2412
	11th to 20th	Day	56% 5% 9% 17% 12% 1	2374
	21st to end	Day	58% 5% 11% 15% 9% 1	2547
May	1st to 10th	Day	64% 5% 10% 14% 7% 1	6357
	11th to 20th	Day	57% 6% 13% 18% 7%	6322
	21st to end	Day	52% 7% 12% 20% 8%	6948
June	1st to 10th	Day	60% 7% 12% 16% 5%	2800
	11th to 20th	Day	53% 6% 11% 21% 8% 1	2800
	21st to end	Day	63% 6% 10% 12% 8% 1	2800
July	1st to 10th	Day	57% 7% 14% 14% 7%	6290
	11th to 20th	Day	47% 9% 15% 22% 7%	6284
	21st to end	Day	43% 8% 18% 23% 8%	6730
August	1st to 10th	Day	56% 8% 13% 18% 6%	4400
	11th to 20th	Day	49% 9% 13% 24% 5%	4214
	21st to end	Day	40% 6% 14% 27% 13%	4317
September	1st to 10th	Day	47% 6% 13% 23% 11% 1	2400
	11th to 20th	Day	48% 6% 11% 24% 11% 1	2400
	21st to end	Day	48% 5% 10% 25% 12%	2120
October	1st to 10th	Day	53% 7% 11% 20% 9% 1	3260
	11th to 20th	Day	43% 7% 10% 26% 13%	3240
	21st to end	Day	52% 6% 13% 18% 9% 1	3331
November	1st to 10th	Day	58% 6% 11% 18% 7%	1815
	11th to 20th	Day	64% 5% 11% 13% 6% 1	1680
	21st to end	Day	60% 8% 12% 14% 6%	1680
December	1st to 10th	Day	57% 7% 8% 21% 6%	2690
	11th to 20th	Day	63% 8% 8% 9% 12%	3075
	21st to end	Day	63% 8% 12% 11% 5% 1	4070
January	1st to 10th	Night	63% 8% 11% 12% 6%	8234
	11th to 20th	Night	68% 5% 8% 14% 5%	8280
	21st to end	Night	53% 6% 8% 14% 16% 3	8716
February	1st to 10th	Night	62% 5% 9% 14% 10% 1	2730
	11th to 20th	Night	59% 8% 10% 15% 8% 1	2666
	21st to end	Night	56% 6% 9% 19% 10% 1	2106
March	1st to 10th	Night	62% 4 6% 14% 12% 2	5401
	11th to 20th	Night	60% 6% 10% 16% 8% 1	5090
	21st to end	Night	70% 3 5% 15% 7% 1	5353
April	1st to 10th	Night	61% 4 10% 13% 10% 2	2011
	11th to 20th	Night	52% 6% 9% 19% 11% 2	1976
	21st to end	Night	57% 4 9% 18% 12% 1	1848
May	1st to 10th	Night	67% 4 7% 13% 7% 1	3620
	11th to 20th	Night	57% 4 9% 22% 7%	3597
	21st to end	Night	54% 8% 11% 21% 6%	3949
June	1st to 10th	Night	60% 6% 9% 18% 6% 1	1600
	11th to 20th	Night	51% 4 12% 19% 13% 1	1600
	21st to end	Night	60% 6% 11% 15% 7% 1	1600
July	1st to 10th	Night	58% 7% 14% 16% 5% 1	3581
	11th to 20th	Night	49% 6% 12% 22% 10% 1	3572
	21st to end	Night	49% 6% 16% 23% 6%	3831
August	1st to 10th	Night	53% 7% 14% 21% 5%	2727
	11th to 20th	Night	50% 7% 15% 22% 4	2899
	21st to end	Night	36% 5% 15% 30% 13%	3580
September	1st to 10th	Night	44% 7% 13% 24% 12%	2000
	11th to 20th	Night	43% 5% 11% 27% 13% 1	2000
	21st to end	Night	48% 6% 9% 26% 11% 1	2278
October	1st to 10th	Night	48% 6% 12% 22% 12%	3920
	11th to 20th	Night	39% 8% 11% 27% 14%	3899
	21st to end	Night	52% 6% 12% 21% 9% 1	4464
November	1st to 10th	Night	55% 8% 12% 17% 6%	2700
	11th to 20th	Night	57% 8% 11% 15% 8% 1	2940
	21st to end	Night	60% 8% 11% 14% 6%	2940
December	1st to 10th	Night	52% 6% 9% 23% 10%	4720
	11th to 20th	Night	60% 6% 8% 15% 9% 2	5355
	21st to end	Night	63% 5% 12% 14% 6%	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% 28% 30% 10% 1	430
	11th to 20th	Day	30% 30% 25% 11% 3	430
	21st to end	Day	25% 28% 34% 10% 2	473
February	1st to 10th	Day	30% 30% 27% 11% 2	430
	11th to 20th	Day	32% 31% 25% 10% 2	426
	21st to end	Day	25% 28% 31% 13% 2	355
March	1st to 10th	Day	26% 29% 34% 10% 1	452
	11th to 20th	Day	25% 31% 30% 10% 3	540
	21st to end	Day	34% 29% 24% 9% 3	594
April	1st to 10th	Day	37% 31% 25% 6% 1	504
	11th to 20th	Day	35% 27% 24% 11% 2	492
	21st to end	Day	32% 21% 29% 14% 3	517
May	1st to 10th	Day	36% 22% 27% 10% 3 2	703
	11th to 20th	Day	26% 20% 30% 18% 5% 1	724
	21st to end	Day	27% 19% 34% 16% 3 1	790
June	1st to 10th	Day	37% 16% 28% 13% 5% 1	730
	11th to 20th	Day	22% 18% 37% 17% 5%	730
	21st to end	Day	32% 13% 32% 18% 4	730
July	1st to 10th	Day	22% 12% 38% 22% 5% 1	720
	11th to 20th	Day	21% 10% 36% 25% 7% 1	718
	21st to end	Day	25% 11% 33% 23% 8% 1	795
August	1st to 10th	Day	17% 10% 36% 29% 7% 1	640
	11th to 20th	Day	23% 10% 34% 23% 9% 1	519
	21st to end	Day	19% 15% 32% 25% 8% 1	583
September	1st to 10th	Day	20% 14% 41% 18% 6% 2	530
	11th to 20th	Day	25% 18% 30% 19% 6% 2	530
	21st to end	Day	23% 18% 29% 22% 6% 2	436
October	1st to 10th	Day	22% 16% 35% 19% 7% 1	420
	11th to 20th	Day	22% 22% 31% 16% 7% 1	420
	21st to end	Day	26% 26% 31% 11% 5% 1	462
November	1st to 10th	Day	29% 22% 32% 11% 4 1	425
	11th to 20th	Day	35% 27% 23% 12% 3	430
	21st to end	Day	29% 29% 29% 9% 3 1	430
December	1st to 10th	Day	34% 23% 30% 11% 3	430
	11th to 20th	Day	36% 28% 28% 7% 2	430
	21st to end	Day	25% 30% 30% 10% 3 1	473
January	1st to 10th	Night	28% 27% 31% 12% 2	950
	11th to 20th	Night	30% 25% 30% 11% 3	950
	21st to end	Night	24% 30% 31% 12% 3	982
February	1st to 10th	Night	29% 21% 33% 13% 4	840
	11th to 20th	Night	27% 32% 29% 10% 3	823
	21st to end	Night	21% 26% 34% 15% 4	692
March	1st to 10th	Night	27% 26% 31% 14% 2	840
	11th to 20th	Night	26% 20% 31% 18% 5%	840
	21st to end	Night	30% 23% 29% 15% 3	819
April	1st to 10th	Night	32% 21% 31% 13% 2	604
	11th to 20th	Night	27% 21% 31% 18% 3	594
	21st to end	Night	33% 16% 28% 19% 4	600
May	1st to 10th	Night	36% 14% 29% 16% 5% 1	600
	11th to 20th	Night	28% 13% 33% 19% 7% 1	592
	21st to end	Night	23% 16% 39% 19% 4 1	649
June	1st to 10th	Night	35% 14% 26% 22% 3	600
	11th to 20th	Night	27% 11% 36% 23% 3	600
	21st to end	Night	32% 8% 34% 22% 5%	600
July	1st to 10th	Night	24% 6% 35% 28% 6% 1	586
	11th to 20th	Night	20% 8% 36% 29% 7%	582
	21st to end	Night	23% 8% 34% 28% 7%	656
August	1st to 10th	Night	20% 5% 33% 30% 11% 1	598
	11th to 20th	Night	21% 8% 31% 29% 11%	592
	21st to end	Night	18% 9% 30% 32% 10% 1	660
September	1st to 10th	Night	21% 9% 34% 27% 8% 1	600
	11th to 20th	Night	22% 11% 31% 25% 11% 1	600
	21st to end	Night	24% 12% 33% 25% 6% 1	708
October	1st to 10th	Night	23% 13% 31% 23% 10% 1	800
	11th to 20th	Night	24% 16% 33% 19% 8% 1	800
	21st to end	Night	29% 22% 30% 15% 4	949
November	1st to 10th	Night	30% 20% 32% 13% 4 1	930
	11th to 20th	Night	31% 24% 26% 14% 4	950
	21st to end	Night	31% 25% 28% 13% 4	950
December	1st to 10th	Night	33% 24% 28% 12% 4	950
	11th to 20th	Night	32% 29% 27% 10% 2	950
	21st to end	Night	30% 27% 28% 11% 3 1	1045

Page generated at 2026-03-30 03:18:44. Version ac07

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