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 2024-12-09.

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	20% 11% 4 9% 5% 5% 5% 4 5% 6% 26%	101892
	Night	20% 11% 4 9% 5% 5% 4 3 5% 6% 27%	98025
Transparency	Day	57% 7% 11% 17% 8% 1	105407
	Night	56% 6% 11% 18% 8% 1	102606
Seeing	Day	28% 21% 31% 15% 4 1	17685
	Night	27% 19% 31% 18% 5%	25215

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	14% 13% 6% 20% 6% 5% 5% 3 5% 5% 19%	2526
	11th to 20th	Day	13% 13% 6% 11% 6% 6% 5% 4 6% 6% 25%	2530
	21st to end	Day	16% 12% 5% 11% 6% 5% 4 3 6% 6% 25%	2950
February	1st to 10th	Day	20% 12% 3 11% 8% 4 5% 3 5% 5% 23%	1710
	11th to 20th	Day	18% 12% 4 10% 7% 7% 5% 4 6% 6% 22%	1663
	21st to end	Day	13% 13% 6% 8% 7% 5% 5% 4 4 6% 28%	1541
March	1st to 10th	Day	23% 14% 4 7% 4 4 4 3 4 4 29%	3176
	11th to 20th	Day	13% 17% 7% 11% 8% 7% 6% 4 4 5% 18%	3480
	21st to end	Day	29% 16% 5% 10% 6% 4 3 3 3 3 18%	3975
April	1st to 10th	Day	23% 15% 4 7% 5% 4 4 3 4 5% 25%	2280
	11th to 20th	Day	23% 12% 3 7% 4 4 3 3 4 6% 30%	2254
	21st to end	Day	22% 14% 3 7% 5% 4 3 4 5% 6% 28%	2419
May	1st to 10th	Day	25% 15% 4 8% 5% 4 4 4 5% 5% 21%	4425
	11th to 20th	Day	21% 13% 3 8% 5% 5% 4 3 5% 5% 28%	4398
	21st to end	Day	18% 11% 3 8% 5% 5% 5% 4 6% 8% 26%	4836
June	1st to 10th	Day	28% 10% 3 7% 4 4 5% 4 6% 7% 22%	2660
	11th to 20th	Day	21% 10% 3 8% 6% 5% 3 4 5% 6% 30%	2660
	21st to end	Day	27% 12% 4 9% 5% 4 4 3 5% 6% 22%	2660
July	1st to 10th	Day	20% 9% 3 9% 6% 5% 6% 4 5% 7% 26%	4440
	11th to 20th	Day	15% 6% 2 7% 6% 6% 6% 5% 8% 8% 28%	4440
	21st to end	Day	17% 8% 3 7% 5% 5% 4 4 7% 8% 32%	4815
August	1st to 10th	Day	17% 10% 4 10% 6% 6% 6% 4 6% 7% 25%	4279
	11th to 20th	Day	18% 8% 3 8% 5% 5% 5% 4 7% 8% 28%	4045
	21st to end	Day	11% 7% 3 7% 5% 4 5% 4 5% 8% 42%	4185
September	1st to 10th	Day	18% 7% 2 7% 5% 5% 5% 3 6% 6% 36%	2280
	11th to 20th	Day	19% 9% 2 7% 4 4 4 4 5% 7% 34%	2280
	21st to end	Day	20% 7% 3 6% 5% 4 4 4 5% 7% 34%	2015
October	1st to 10th	Day	19% 9% 3 7% 5% 5% 5% 4 5% 7% 31%	1900
	11th to 20th	Day	21% 8% 3 8% 4 5% 5% 5% 7% 8% 27%	1900
	21st to end	Day	21% 12% 4 8% 6% 4 5% 4 5% 6% 24%	1970
November	1st to 10th	Day	23% 13% 3 6% 6% 4 5% 3 5% 7% 26%	1727
	11th to 20th	Day	23% 15% 4 10% 5% 5% 4 3 4 7% 21%	1600
	21st to end	Day	15% 16% 4 8% 6% 6% 5% 4 7% 7% 23%	1600
December	1st to 10th	Day	20% 17% 4 11% 5% 5% 5% 4 6% 5% 17%	1584
	11th to 20th	Day	32% 12% 5% 9% 6% 5% 5% 4 5% 5% 15%	1906
	21st to end	Day	23% 12% 8% 12% 5% 4 3 3 5% 5% 19%	2783
January	1st to 10th	Night	14% 13% 5% 15% 6% 5% 5% 4 6% 6% 21%	4429
	11th to 20th	Night	18% 12% 4 12% 6% 5% 5% 3 5% 5% 23%	4440
	21st to end	Night	16% 11% 5% 15% 6% 5% 5% 3 5% 6% 24%	4710
February	1st to 10th	Night	20% 12% 4 10% 6% 6% 4 4 5% 5% 24%	2470
	11th to 20th	Night	17% 12% 5% 10% 6% 5% 5% 4 5% 7% 23%	2403
	21st to end	Night	12% 13% 7% 10% 5% 5% 5% 4 5% 5% 29%	1912
March	1st to 10th	Night	21% 13% 4 9% 5% 5% 4 3 4 5% 26%	3662
	11th to 20th	Night	21% 12% 5% 9% 6% 5% 5% 4 4 5% 22%	3479
	21st to end	Night	28% 14% 6% 10% 5% 4 3 2 3 3 22%	3657
April	1st to 10th	Night	24% 13% 4 7% 4 5% 4 3 3 6% 26%	1900
	11th to 20th	Night	21% 10% 2 7% 4 4 5% 5% 6% 6% 30%	1876
	21st to end	Night	25% 11% 3 7% 5% 4 4 3 4 5% 29%	1756
May	1st to 10th	Night	25% 13% 3 10% 7% 5% 5% 3 4 5% 20%	2525
	11th to 20th	Night	22% 16% 3 7% 4 3 3 3 5% 5% 30%	2506
	21st to end	Night	19% 12% 4 8% 6% 5% 5% 4 6% 7% 24%	2749
June	1st to 10th	Night	29% 11% 3 8% 4 4 4 4 4 5% 24%	1520
	11th to 20th	Night	22% 10% 3 6% 4 4 4 3 5% 7% 32%	1520
	21st to end	Night	27% 10% 3 8% 5% 3 4 3 5% 8% 23%	1520
July	1st to 10th	Night	19% 10% 4 10% 6% 6% 4 4 7% 7% 24%	2530
	11th to 20th	Night	15% 10% 4 9% 4 6% 5% 5% 6% 8% 28%	2530
	21st to end	Night	18% 10% 3 7% 5% 4 5% 3 5% 7% 33%	2750
August	1st to 10th	Night	15% 9% 4 10% 7% 6% 4 4 4 6% 30%	2654
	11th to 20th	Night	16% 9% 4 8% 5% 5% 5% 3 7% 7% 30%	2782
	21st to end	Night	13% 6% 2 5% 4 4 4 3 5% 7% 46%	3471
September	1st to 10th	Night	17% 7% 3 6% 4 4 5% 4 6% 8% 37%	1900
	11th to 20th	Night	18% 7% 2 6% 4 5% 3 3 4 7% 41%	1900
	21st to end	Night	20% 8% 4 7% 4 4 4 2 4 6% 37%	2163
October	1st to 10th	Night	19% 7% 2 6% 4 3 4 3 5% 8% 36%	2280
	11th to 20th	Night	21% 7% 3 7% 5% 4 4 4 5% 6% 35%	2280
	21st to end	Night	24% 11% 3 8% 5% 5% 3 3 5% 6% 27%	2627
November	1st to 10th	Night	20% 13% 3 8% 5% 4 4 3 6% 7% 26%	2568
	11th to 20th	Night	21% 14% 3 8% 5% 5% 5% 5% 5% 6% 25%	2800
	21st to end	Night	20% 14% 4 9% 6% 5% 4 4 6% 5% 24%	2800
December	1st to 10th	Night	24% 14% 4 9% 5% 3 4 3 5% 6% 22%	2779
	11th to 20th	Night	31% 12% 4 8% 5% 4 3 3 5% 5% 19%	3293
	21st to end	Night	28% 12% 6% 11% 4 4 3 3 3 5% 20%	4884

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	66% 6% 10% 13% 5%	2527
	11th to 20th	Day	58% 6% 11% 16% 9%	2530
	21st to end	Day	58% 8% 6% 14% 11% 1	2950
February	1st to 10th	Day	63% 5% 10% 12% 10% 1	1710
	11th to 20th	Day	61% 6% 10% 15% 8%	1671
	21st to end	Day	56% 5% 8% 17% 10% 3	1541
March	1st to 10th	Day	59% 4 9% 15% 12% 1	3180
	11th to 20th	Day	68% 7% 7% 12% 5% 1	3480
	21st to end	Day	72% 4 7% 10% 6% 2	3975
April	1st to 10th	Day	61% 5% 8% 13% 10% 3	2280
	11th to 20th	Day	55% 5% 9% 17% 13% 1	2254
	21st to end	Day	57% 5% 11% 15% 10% 1	2419
May	1st to 10th	Day	66% 5% 10% 12% 5% 1	4440
	11th to 20th	Day	57% 7% 11% 18% 7%	4402
	21st to end	Day	53% 9% 15% 16% 6%	4836
June	1st to 10th	Day	61% 7% 12% 15% 4	2660
	11th to 20th	Day	54% 6% 11% 20% 9% 1	2660
	21st to end	Day	64% 7% 10% 12% 7% 1	2660
July	1st to 10th	Day	56% 8% 13% 14% 9%	4370
	11th to 20th	Day	48% 11% 17% 18% 7%	4364
	21st to end	Day	48% 8% 16% 19% 9%	4662
August	1st to 10th	Day	57% 8% 13% 17% 5%	4265
	11th to 20th	Day	50% 9% 13% 23% 5%	4084
	21st to end	Day	40% 6% 14% 27% 13%	4185
September	1st to 10th	Day	47% 6% 13% 22% 10% 1	2280
	11th to 20th	Day	48% 6% 11% 24% 11% 1	2280
	21st to end	Day	49% 5% 10% 25% 11%	2015
October	1st to 10th	Day	54% 7% 11% 19% 9% 1	3160
	11th to 20th	Day	42% 7% 10% 26% 13%	3140
	21st to end	Day	52% 6% 14% 18% 10% 1	3228
November	1st to 10th	Day	58% 7% 11% 18% 7%	1727
	11th to 20th	Day	63% 6% 11% 12% 7% 1	1600
	21st to end	Day	60% 9% 12% 13% 6%	1600
December	1st to 10th	Day	64% 8% 10% 14% 3	1584
	11th to 20th	Day	71% 8% 7% 10% 4 1	1905
	21st to end	Day	66% 8% 15% 7% 4 1	2783
January	1st to 10th	Night	57% 12% 15% 12% 3	4429
	11th to 20th	Night	60% 6% 11% 16% 6%	4440
	21st to end	Night	60% 7% 10% 12% 10% 1	4710
February	1st to 10th	Night	62% 5% 9% 13% 10% 1	2470
	11th to 20th	Night	59% 8% 10% 14% 8% 1	2406
	21st to end	Night	55% 6% 9% 19% 10% 1	1912
March	1st to 10th	Night	61% 4 7% 16% 11% 2	3671
	11th to 20th	Night	64% 5% 8% 16% 6% 1	3480
	21st to end	Night	69% 3 6% 15% 6% 1	3657
April	1st to 10th	Night	60% 4 10% 13% 10% 2	1900
	11th to 20th	Night	52% 7% 9% 19% 12% 2	1876
	21st to end	Night	57% 4 9% 17% 12% 1	1756
May	1st to 10th	Night	68% 4 9% 13% 5%	2530
	11th to 20th	Night	56% 5% 10% 22% 6%	2507
	21st to end	Night	56% 10% 12% 17% 5%	2750
June	1st to 10th	Night	62% 6% 10% 17% 5%	1520
	11th to 20th	Night	51% 4 13% 19% 12% 1	1520
	21st to end	Night	61% 6% 11% 15% 7%	1520
July	1st to 10th	Night	58% 6% 13% 15% 7% 1	2491
	11th to 20th	Night	52% 8% 15% 18% 7%	2482
	21st to end	Night	50% 6% 15% 20% 8% 1	2663
August	1st to 10th	Night	54% 7% 14% 21% 4	2643
	11th to 20th	Night	51% 8% 15% 22% 4	2809
	21st to end	Night	36% 5% 15% 30% 13%	3470
September	1st to 10th	Night	44% 7% 13% 24% 12%	1900
	11th to 20th	Night	43% 5% 11% 27% 13% 1	1900
	21st to end	Night	49% 6% 9% 25% 10% 1	2163
October	1st to 10th	Night	49% 5% 12% 22% 11%	3800
	11th to 20th	Night	38% 8% 11% 28% 14%	3779
	21st to end	Night	52% 6% 12% 20% 9% 1	4326
November	1st to 10th	Night	55% 8% 13% 17% 7%	2568
	11th to 20th	Night	57% 9% 12% 14% 8% 1	2800
	21st to end	Night	61% 8% 12% 14% 6%	2800
December	1st to 10th	Night	63% 6% 10% 15% 6%	2779
	11th to 20th	Night	68% 6% 9% 12% 5% 1	3295
	21st to end	Night	67% 6% 12% 11% 3	4884

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	370
	11th to 20th	Day	29% 31% 26% 11% 2	370
	21st to end	Day	25% 29% 33% 11% 3	407
February	1st to 10th	Day	30% 31% 26% 11% 2	370
	11th to 20th	Day	32% 33% 23% 10% 1	366
	21st to end	Day	25% 27% 32% 13% 2	307
March	1st to 10th	Day	27% 28% 34% 9% 1	388
	11th to 20th	Day	26% 30% 29% 11% 4	460
	21st to end	Day	34% 30% 23% 10% 3	506
April	1st to 10th	Day	36% 31% 25% 6% 1	460
	11th to 20th	Day	35% 28% 24% 11% 2	452
	21st to end	Day	33% 21% 29% 14% 3	476
May	1st to 10th	Day	36% 23% 27% 9% 3 2	653
	11th to 20th	Day	26% 20% 30% 17% 5% 1	674
	21st to end	Day	28% 19% 34% 15% 3 1	735
June	1st to 10th	Day	38% 17% 28% 13% 4 1	680
	11th to 20th	Day	24% 18% 37% 17% 4	680
	21st to end	Day	34% 12% 32% 18% 4	680
July	1st to 10th	Day	23% 12% 38% 21% 5% 1	670
	11th to 20th	Day	22% 10% 38% 23% 6% 1	668
	21st to end	Day	26% 11% 32% 23% 8% 1	740
August	1st to 10th	Day	18% 10% 36% 28% 7% 1	595
	11th to 20th	Day	24% 11% 33% 22% 10% 1	479
	21st to end	Day	19% 15% 32% 25% 8% 1	539
September	1st to 10th	Day	20% 14% 41% 17% 6% 1	490
	11th to 20th	Day	26% 17% 30% 19% 6% 1	490
	21st to end	Day	24% 17% 28% 22% 6% 2	405
October	1st to 10th	Day	23% 16% 34% 18% 7% 2	390
	11th to 20th	Day	23% 23% 33% 14% 6% 2	390
	21st to end	Day	26% 27% 31% 11% 5% 1	429
November	1st to 10th	Day	27% 23% 33% 12% 4 1	395
	11th to 20th	Day	35% 28% 23% 11% 3 1	400
	21st to end	Day	30% 29% 28% 10% 3 1	400
December	1st to 10th	Day	34% 22% 30% 10% 3	394
	11th to 20th	Day	36% 29% 27% 7% 1	370
	21st to end	Day	25% 31% 30% 10% 3 1	407
January	1st to 10th	Night	28% 27% 31% 12% 2	850
	11th to 20th	Night	30% 26% 31% 11% 3	850
	21st to end	Night	25% 28% 32% 12% 3	884
February	1st to 10th	Night	29% 21% 33% 14% 3	760
	11th to 20th	Night	27% 33% 28% 10% 2	743
	21st to end	Night	20% 27% 33% 16% 4	628
March	1st to 10th	Night	27% 25% 31% 14% 2	760
	11th to 20th	Night	25% 21% 31% 18% 6%	760
	21st to end	Night	29% 23% 30% 15% 3	741
April	1st to 10th	Night	32% 20% 32% 14% 3	570
	11th to 20th	Night	27% 21% 32% 17% 3	564
	21st to end	Night	33% 16% 28% 19% 4	570
May	1st to 10th	Night	36% 14% 29% 15% 5% 1	570
	11th to 20th	Night	28% 13% 32% 19% 7% 1	562
	21st to end	Night	23% 16% 39% 18% 3 1	616
June	1st to 10th	Night	36% 13% 26% 22% 3	570
	11th to 20th	Night	27% 11% 36% 23% 3	570
	21st to end	Night	33% 7% 35% 21% 5%	570
July	1st to 10th	Night	25% 6% 35% 28% 6% 1	556
	11th to 20th	Night	20% 8% 36% 28% 7%	552
	21st to end	Night	23% 8% 34% 28% 7%	623
August	1st to 10th	Night	21% 5% 34% 30% 10% 1	568
	11th to 20th	Night	22% 7% 31% 29% 11%	562
	21st to end	Night	18% 8% 30% 32% 11% 1	627
September	1st to 10th	Night	21% 9% 35% 27% 8% 1	570
	11th to 20th	Night	22% 11% 31% 24% 11% 1	570
	21st to end	Night	25% 12% 32% 24% 6%	672
October	1st to 10th	Night	23% 13% 31% 22% 10% 1	760
	11th to 20th	Night	24% 16% 33% 18% 7% 1	760
	21st to end	Night	29% 22% 30% 14% 4	899
November	1st to 10th	Night	29% 20% 32% 14% 4 1	880
	11th to 20th	Night	31% 24% 27% 14% 4	900
	21st to end	Night	32% 25% 27% 12% 4	900
December	1st to 10th	Night	33% 24% 28% 12% 4	893
	11th to 20th	Night	32% 29% 27% 10% 2	850
	21st to end	Night	30% 28% 28% 11% 3 1	935

Page generated at 2024-12-06 04:54:46. Version ac07

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