Gore Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gore Bay clear sky chart from 2005-11-06 to 2026-07-01.

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	13% 10% 4 8% 5% 4 4 3 5% 7% 36%	137630
	Night	14% 12% 5% 10% 5% 5% 5% 4 5% 6% 30%	134885
Transparency	Day	47% 6% 12% 23% 12% 1	141114
	Night	52% 6% 11% 19% 11% 1	139489
Seeing	Day	18% 11% 29% 27% 12% 3	17532
	Night	20% 11% 29% 27% 11% 1	26828

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% 19% 9% 14% 6% 5% 6% 4 4 5% 17%	4187
	11th to 20th	Day	9% 19% 8% 17% 9% 7% 5% 3 3 4 17%	4679
	21st to end	Day	10% 16% 8% 16% 7% 5% 5% 4 5% 5% 20%	5344
February	1st to 10th	Day	9% 16% 5% 13% 7% 4 5% 4 5% 6% 26%	1890
	11th to 20th	Day	11% 15% 4 11% 6% 5% 6% 4 5% 6% 28%	1849
	21st to end	Day	11% 16% 5% 11% 7% 5% 5% 3 5% 6% 26%	1730
March	1st to 10th	Day	15% 11% 3 7% 4 5% 4 4 5% 5% 37%	4733
	11th to 20th	Day	10% 13% 5% 11% 6% 5% 5% 4 5% 7% 30%	5090
	21st to end	Day	16% 11% 5% 8% 4 4 4 3 5% 5% 34%	5586
April	1st to 10th	Day	16% 11% 3 8% 5% 4 4 3 5% 7% 32%	2482
	11th to 20th	Day	18% 8% 3 7% 4 4 4 2 6% 6% 38%	2702
	21st to end	Day	18% 8% 2 7% 4 4 4 4 5% 8% 36%	2730
May	1st to 10th	Day	13% 7% 2 6% 3 4 4 3 6% 8% 45%	7642
	11th to 20th	Day	13% 8% 3 7% 4 4 4 3 5% 6% 43%	7864
	21st to end	Day	14% 7% 3 6% 4 3 3 3 5% 6% 46%	9530
June	1st to 10th	Day	13% 6% 2 5% 5% 4 4 4 6% 8% 43%	3150
	11th to 20th	Day	12% 5% 2 7% 5% 4 5% 4 7% 8% 43%	3150
	21st to end	Day	12% 7% 3 7% 4 4 4 4 5% 8% 42%	3150
July	1st to 10th	Day	14% 8% 2 6% 4 3 4 3 6% 8% 42%	6820
	11th to 20th	Day	9% 5% 2 6% 4 4 3 3 5% 6% 54%	6644
	21st to end	Day	9% 5% 2 4 3 3 3 3 5% 8% 54%	6800
August	1st to 10th	Day	8% 6% 2 6% 5% 4 5% 4 6% 8% 46%	4234
	11th to 20th	Day	14% 6% 2 5% 4 3 3 3 5% 8% 46%	4174
	21st to end	Day	9% 7% 3 5% 4 5% 4 4 6% 7% 47%	4675
September	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 6% 8% 42%	2360
	11th to 20th	Day	12% 5% 1 5% 3 5% 4 4 5% 9% 47%	2200
	21st to end	Day	17% 9% 3 6% 4 4 4 4 5% 8% 38%	2200
October	1st to 10th	Day	17% 8% 3 8% 5% 4 3 3 4 6% 38%	2075
	11th to 20th	Day	20% 12% 3 8% 6% 5% 5% 4 4 7% 26%	2000
	21st to end	Day	22% 12% 4 10% 6% 4 4 3 5% 7% 22%	2013
November	1st to 10th	Day	17% 14% 4 10% 6% 4 5% 3 4 7% 27%	1841
	11th to 20th	Day	14% 16% 6% 12% 7% 5% 5% 4 5% 7% 20%	1680
	21st to end	Day	20% 22% 5% 12% 7% 4 5% 3 4 6% 13%	1680
December	1st to 10th	Day	15% 20% 8% 13% 7% 6% 5% 3 5% 5% 12%	2502
	11th to 20th	Day	16% 18% 7% 15% 7% 5% 7% 4 6% 5% 11%	2691
	21st to end	Day	24% 23% 7% 11% 5% 3 4 3 4 4 12%	3553
January	1st to 10th	Night	10% 15% 7% 16% 7% 7% 7% 4 5% 6% 17%	8734
	11th to 20th	Night	11% 18% 7% 15% 7% 6% 4 3 5% 5% 19%	8236
	21st to end	Night	8% 14% 7% 15% 7% 6% 6% 4 6% 6% 21%	8846
February	1st to 10th	Night	11% 14% 5% 12% 7% 6% 5% 5% 6% 5% 26%	2730
	11th to 20th	Night	10% 15% 5% 12% 7% 5% 5% 3 6% 6% 26%	2652
	21st to end	Night	12% 15% 5% 9% 7% 5% 5% 4 5% 6% 26%	2076
March	1st to 10th	Night	15% 10% 3 7% 4 3 4 3 4 7% 39%	5326
	11th to 20th	Night	12% 11% 5% 9% 5% 5% 5% 4 5% 7% 33%	5089
	21st to end	Night	18% 11% 6% 9% 4 4 4 2 4 5% 34%	5588
April	1st to 10th	Night	17% 10% 4 7% 4 4 5% 3 5% 6% 34%	2155
	11th to 20th	Night	19% 8% 3 6% 4 4 4 3 6% 6% 39%	1867
	21st to end	Night	17% 10% 4 9% 5% 4 4 3 5% 6% 34%	1890
May	1st to 10th	Night	13% 8% 3 8% 5% 5% 4 3 6% 7% 38%	5257
	11th to 20th	Night	13% 8% 3 8% 4 4 4 3 4 7% 42%	4982
	21st to end	Night	15% 8% 3 6% 3 3 3 3 4 7% 44%	4665
June	1st to 10th	Night	12% 6% 2 5% 5% 5% 4 5% 6% 8% 42%	1470
	11th to 20th	Night	10% 7% 3 6% 4 4 6% 5% 6% 8% 41%	1470
	21st to end	Night	12% 6% 2 8% 4 4 6% 4 6% 6% 41%	1470
July	1st to 10th	Night	12% 7% 2 6% 4 4 4 3 6% 8% 42%	3160
	11th to 20th	Night	10% 5% 2 5% 4 3 4 3 6% 8% 51%	3333
	21st to end	Night	7% 5% 2 6% 4 4 5% 4 5% 9% 50%	4065
August	1st to 10th	Night	7% 5% 2 6% 5% 5% 5% 5% 7% 8% 44%	2915
	11th to 20th	Night	13% 6% 2 6% 4 5% 4 4 6% 8% 42%	2875
	21st to end	Night	8% 5% 2 6% 4 4 4 3 5% 7% 51%	3223
September	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 46%	2016
	11th to 20th	Night	12% 5% 2 5% 4 4 3 3 4 8% 51%	2200
	21st to end	Night	16% 9% 3 7% 5% 4 3 3 5% 7% 39%	2200
October	1st to 10th	Night	18% 8% 3 8% 4 4 4 2 4 5% 39%	2324
	11th to 20th	Night	23% 11% 3 9% 5% 4 5% 4 5% 6% 26%	2400
	21st to end	Night	23% 14% 4 10% 5% 4 4 3 4 5% 23%	2825
November	1st to 10th	Night	16% 13% 4 8% 7% 5% 5% 4 6% 5% 27%	2674
	11th to 20th	Night	16% 17% 6% 11% 7% 5% 5% 4 4 5% 21%	2940
	21st to end	Night	19% 20% 6% 12% 7% 5% 5% 3 4 5% 16%	2940
December	1st to 10th	Night	15% 19% 7% 14% 7% 6% 5% 4 4 5% 15%	4889
	11th to 20th	Night	14% 17% 6% 15% 8% 6% 5% 4 5% 5% 15%	5736
	21st to end	Night	22% 23% 7% 11% 6% 4 5% 3 4 3 11%	7667

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	67% 5% 9% 14% 4 1	4188
	11th to 20th	Day	71% 5% 7% 10% 7% 1	4710
	21st to end	Day	65% 5% 7% 13% 10%	5344
February	1st to 10th	Day	57% 6% 12% 17% 7% 1	1890
	11th to 20th	Day	56% 6% 11% 17% 9% 1	1858
	21st to end	Day	59% 5% 8% 19% 9% 1	1730
March	1st to 10th	Day	47% 5% 14% 12% 17% 5%	4736
	11th to 20th	Day	53% 6% 12% 18% 10% 1	5090
	21st to end	Day	51% 5% 14% 16% 12% 2	5586
April	1st to 10th	Day	51% 5% 12% 19% 12% 1	2482
	11th to 20th	Day	47% 5% 9% 25% 13% 2	2702
	21st to end	Day	46% 5% 10% 20% 14% 3	2730
May	1st to 10th	Day	37% 5% 10% 28% 16% 3	7651
	11th to 20th	Day	42% 5% 10% 22% 19% 2	7868
	21st to end	Day	39% 5% 11% 24% 18% 3	9531
June	1st to 10th	Day	38% 5% 12% 27% 16% 2	3150
	11th to 20th	Day	37% 6% 13% 27% 16% 1	3150
	21st to end	Day	40% 6% 14% 25% 14% 2	3150
July	1st to 10th	Day	39% 6% 14% 28% 12% 1	6747
	11th to 20th	Day	30% 6% 13% 40% 10% 1	6563
	21st to end	Day	29% 5% 14% 35% 18%	6604
August	1st to 10th	Day	34% 7% 14% 32% 13% 1	4221
	11th to 20th	Day	37% 6% 17% 27% 12%	4213
	21st to end	Day	34% 7% 15% 33% 10% 1	4674
September	1st to 10th	Day	38% 7% 15% 27% 12% 1	2360
	11th to 20th	Day	35% 5% 17% 31% 11%	2200
	21st to end	Day	44% 6% 16% 23% 10%	2200
October	1st to 10th	Day	37% 5% 11% 30% 18%	3374
	11th to 20th	Day	48% 6% 14% 23% 10%	3240
	21st to end	Day	59% 6% 12% 16% 7%	3225
November	1st to 10th	Day	57% 6% 13% 19% 6%	1841
	11th to 20th	Day	62% 8% 13% 12% 5%	1680
	21st to end	Day	72% 6% 11% 9% 2	1680
December	1st to 10th	Day	70% 9% 11% 8% 2	2502
	11th to 20th	Day	70% 7% 11% 10% 2	2691
	21st to end	Day	74% 6% 8% 9% 3	3553
January	1st to 10th	Night	65% 6% 11% 12% 5% 1	8734
	11th to 20th	Night	67% 4 10% 11% 8%	8280
	21st to end	Night	62% 6% 9% 13% 10% 1	8846
February	1st to 10th	Night	59% 5% 10% 17% 8% 1	2730
	11th to 20th	Night	57% 5% 11% 17% 8% 1	2654
	21st to end	Night	57% 5% 11% 18% 9%	2076
March	1st to 10th	Night	46% 4 14% 18% 15% 3	5336
	11th to 20th	Night	49% 4 17% 20% 9% 1	5090
	21st to end	Night	53% 4 8% 18% 15% 2	5588
April	1st to 10th	Night	50% 5% 10% 19% 14% 1	2155
	11th to 20th	Night	45% 4 7% 24% 17% 2	1867
	21st to end	Night	52% 5% 8% 17% 15% 3	1890
May	1st to 10th	Night	44% 6% 8% 25% 15% 3	5264
	11th to 20th	Night	43% 4 7% 25% 18% 2	4983
	21st to end	Night	41% 4 8% 26% 16% 5%	4666
June	1st to 10th	Night	39% 4 12% 24% 19% 3	1470
	11th to 20th	Night	37% 6% 12% 24% 19% 2	1470
	21st to end	Night	41% 6% 14% 24% 13% 2	1470
July	1st to 10th	Night	39% 6% 15% 25% 13% 2	3125
	11th to 20th	Night	31% 4 14% 36% 14% 1	3291
	21st to end	Night	30% 6% 13% 32% 18%	3947
August	1st to 10th	Night	34% 6% 16% 30% 13% 1	2904
	11th to 20th	Night	37% 9% 14% 26% 13%	2902
	21st to end	Night	32% 6% 14% 32% 15% 1	3223
September	1st to 10th	Night	37% 6% 15% 28% 13% 2	2016
	11th to 20th	Night	33% 5% 16% 34% 12% 1	2200
	21st to end	Night	45% 6% 15% 24% 11%	2200
October	1st to 10th	Night	38% 5% 10% 31% 16%	3805
	11th to 20th	Night	46% 6% 14% 23% 10%	3899
	21st to end	Night	54% 7% 16% 17% 6%	4563
November	1st to 10th	Night	55% 7% 12% 19% 7%	2674
	11th to 20th	Night	64% 6% 13% 11% 5%	2940
	21st to end	Night	70% 6% 11% 10% 2	2940
December	1st to 10th	Night	69% 8% 11% 10% 2	4889
	11th to 20th	Night	67% 6% 10% 9% 6% 1	5735
	21st to end	Night	75% 5% 8% 8% 3	7667

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	23% 14% 33% 21% 6% 3	236
	11th to 20th	Day	19% 13% 36% 23% 8% 1	330
	21st to end	Day	21% 14% 29% 27% 7% 1	363
February	1st to 10th	Day	19% 21% 35% 19% 5% 1	330
	11th to 20th	Day	19% 18% 38% 20% 5%	330
	21st to end	Day	21% 25% 32% 21% 2	273
March	1st to 10th	Day	19% 19% 36% 19% 5% 1	395
	11th to 20th	Day	20% 14% 33% 24% 8% 1	540
	21st to end	Day	26% 15% 29% 22% 7% 1	594
April	1st to 10th	Day	23% 13% 27% 26% 10% 1	540
	11th to 20th	Day	27% 12% 27% 20% 10% 4	532
	21st to end	Day	24% 11% 30% 22% 11% 2	540
May	1st to 10th	Day	20% 8% 32% 28% 10% 3	543
	11th to 20th	Day	16% 10% 29% 25% 16% 4	567
	21st to end	Day	13% 8% 30% 31% 15% 3	775
June	1st to 10th	Day	14% 8% 29% 34% 13% 2	780
	11th to 20th	Day	15% 8% 30% 32% 12% 3	780
	21st to end	Day	16% 10% 27% 32% 13% 3	780
July	1st to 10th	Day	9% 6% 28% 36% 18% 2	722
	11th to 20th	Day	11% 6% 30% 33% 17% 4	718
	21st to end	Day	12% 6% 26% 34% 17% 5%	744
August	1st to 10th	Day	12% 6% 19% 34% 23% 6%	526
	11th to 20th	Day	11% 3 19% 32% 24% 10%	519
	21st to end	Day	13% 7% 26% 28% 19% 7%	583
September	1st to 10th	Day	15% 9% 23% 25% 21% 7%	530
	11th to 20th	Day	14% 5% 20% 28% 25% 7%	530
	21st to end	Day	22% 11% 19% 28% 18% 3	530
October	1st to 10th	Day	19% 17% 23% 23% 16% 2	530
	11th to 20th	Day	22% 17% 34% 21% 6% 1	530
	21st to end	Day	27% 17% 33% 19% 4	396
November	1st to 10th	Day	27% 15% 34% 19% 5% 1	324
	11th to 20th	Day	23% 23% 30% 22% 2	220
	21st to end	Day	28% 24% 27% 17% 4	220
December	1st to 10th	Day	27% 14% 32% 18% 6% 3	220
	11th to 20th	Day	30% 20% 33% 15% 3	220
	21st to end	Day	35% 17% 34% 11% 3	242
January	1st to 10th	Night	21% 13% 35% 23% 7% 1	1050
	11th to 20th	Night	22% 13% 33% 23% 8% 1	1050
	21st to end	Night	19% 10% 32% 29% 9% 1	1086
February	1st to 10th	Night	19% 14% 37% 23% 7%	840
	11th to 20th	Night	19% 13% 32% 27% 9%	823
	21st to end	Night	21% 12% 38% 24% 5% 1	692
March	1st to 10th	Night	17% 13% 38% 26% 6%	840
	11th to 20th	Night	19% 13% 35% 25% 8%	840
	21st to end	Night	19% 10% 32% 30% 8% 1	924
April	1st to 10th	Night	23% 11% 34% 25% 7%	740
	11th to 20th	Night	24% 10% 27% 26% 12% 1	623
	21st to end	Night	22% 11% 28% 27% 12% 1	630
May	1st to 10th	Night	15% 5% 28% 38% 12% 1	630
	11th to 20th	Night	17% 6% 28% 33% 14% 1	538
	21st to end	Night	15% 7% 26% 35% 16% 1	455
June	1st to 10th	Night	14% 6% 29% 36% 15%	420
	11th to 20th	Night	13% 8% 23% 38% 17% 1	420
	21st to end	Night	15% 5% 23% 40% 15% 2	420
July	1st to 10th	Night	9% 4 23% 46% 18% 1	390
	11th to 20th	Night	9% 2 22% 39% 24% 3	457
	21st to end	Night	10% 4 23% 38% 23% 2	657
August	1st to 10th	Night	11% 3 21% 40% 22% 3	597
	11th to 20th	Night	12% 4 19% 29% 32% 4	594
	21st to end	Night	12% 5% 22% 35% 22% 4	660
September	1st to 10th	Night	15% 9% 21% 33% 16% 6%	723
	11th to 20th	Night	13% 5% 22% 32% 21% 7%	800
	21st to end	Night	19% 8% 22% 29% 17% 4	800
October	1st to 10th	Night	21% 11% 26% 25% 15% 2	800
	11th to 20th	Night	29% 12% 27% 24% 7% 1	800
	21st to end	Night	30% 12% 30% 22% 4 1	880
November	1st to 10th	Night	25% 15% 28% 24% 8%	820
	11th to 20th	Night	24% 18% 30% 19% 8%	840
	21st to end	Night	29% 16% 33% 17% 4	840
December	1st to 10th	Night	26% 18% 32% 18% 6% 1	944
	11th to 20th	Night	25% 18% 37% 15% 5% 1	1050
	21st to end	Night	32% 14% 30% 17% 6%	1155

Page generated at 2026-06-28 02:10:49. Version ac07

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