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 2025-02-25.

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% 35%	108230
	Night	14% 12% 5% 10% 6% 5% 5% 4 5% 6% 30%	110545
Transparency	Day	47% 6% 12% 22% 12% 1	111761
	Night	53% 6% 12% 19% 10% 1	115177
Seeing	Day	18% 11% 28% 28% 13% 3	15671
	Night	20% 10% 29% 27% 11% 1	25158

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% 18% 9% 13% 6% 5% 6% 4 4 6% 19%	3223
	11th to 20th	Day	9% 16% 7% 16% 9% 8% 6% 4 4 4 17%	3589
	21st to end	Day	12% 18% 9% 16% 7% 5% 5% 3 4 5% 15%	4131
February	1st to 10th	Day	9% 16% 5% 13% 7% 4 5% 4 5% 6% 26%	1800
	11th to 20th	Day	10% 15% 4 11% 6% 5% 6% 3 5% 5% 29%	1758
	21st to end	Day	11% 16% 5% 11% 7% 5% 4 3 5% 6% 27%	1610
March	1st to 10th	Day	14% 12% 4 7% 4 4 4 4 5% 5% 37%	3228
	11th to 20th	Day	8% 13% 5% 11% 6% 5% 5% 4 4 6% 33%	3480
	21st to end	Day	13% 10% 5% 9% 5% 5% 4 4 5% 6% 35%	3815
April	1st to 10th	Day	16% 11% 3 8% 5% 4 4 3 5% 7% 33%	2244
	11th to 20th	Day	18% 8% 3 8% 4 4 4 2 6% 6% 36%	2442
	21st to end	Day	19% 8% 2 7% 4 4 3 4 5% 7% 37%	2470
May	1st to 10th	Day	14% 7% 2 6% 4 4 4 3 5% 7% 44%	4108
	11th to 20th	Day	11% 7% 3 7% 4 4 4 3 5% 6% 44%	4207
	21st to end	Day	13% 6% 2 6% 4 4 4 3 5% 7% 47%	5083
June	1st to 10th	Day	13% 6% 2 5% 5% 4 4 4 6% 8% 42%	2850
	11th to 20th	Day	11% 5% 2 6% 5% 4 5% 4 7% 8% 43%	2850
	21st to end	Day	12% 7% 3 7% 4 4 4 4 5% 8% 43%	2850
July	1st to 10th	Day	15% 9% 2 6% 4 3 4 3 5% 7% 41%	4760
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 5% 7% 53%	4640
	21st to end	Day	10% 5% 2 4 3 3 3 3 5% 7% 54%	4730
August	1st to 10th	Day	8% 6% 2 6% 5% 4 5% 3 6% 8% 46%	4104
	11th to 20th	Day	15% 6% 2 6% 3 3 3 3 5% 8% 46%	4044
	21st to end	Day	10% 7% 2 5% 4 5% 4 4 6% 7% 47%	4532
September	1st to 10th	Day	12% 6% 2 6% 4 3 4 4 6% 8% 43%	2242
	11th to 20th	Day	12% 5% 1 5% 3 4 4 4 5% 9% 46%	2090
	21st to end	Day	17% 9% 2 6% 4 4 4 4 5% 8% 38%	2090
October	1st to 10th	Day	18% 8% 3 8% 5% 4 3 3 4 6% 38%	1971
	11th to 20th	Day	20% 13% 3 8% 6% 5% 6% 4 4 7% 25%	1900
	21st to end	Day	23% 12% 4 10% 6% 4 4 3 5% 6% 21%	1913
November	1st to 10th	Day	16% 14% 4 10% 6% 3 5% 4 4 7% 27%	1752
	11th to 20th	Day	14% 16% 6% 12% 7% 5% 5% 4 5% 7% 20%	1600
	21st to end	Day	20% 22% 5% 11% 6% 4 5% 3 4 6% 14%	1600
December	1st to 10th	Day	15% 20% 8% 13% 7% 6% 5% 3 5% 5% 12%	2427
	11th to 20th	Day	16% 18% 7% 15% 7% 5% 7% 4 6% 5% 11%	2621
	21st to end	Day	24% 23% 7% 11% 5% 3 5% 3 4 4 12%	3476
January	1st to 10th	Night	10% 14% 7% 15% 7% 6% 7% 4 6% 6% 19%	6739
	11th to 20th	Night	11% 16% 6% 14% 7% 6% 4 4 5% 6% 21%	6316
	21st to end	Night	11% 17% 8% 15% 6% 6% 5% 4 5% 5% 19%	6840
February	1st to 10th	Night	11% 14% 5% 12% 7% 6% 5% 5% 6% 5% 25%	2600
	11th to 20th	Night	10% 15% 4 11% 7% 5% 5% 3 6% 6% 26%	2523
	21st to end	Night	13% 15% 5% 9% 7% 5% 5% 4 5% 6% 26%	1939
March	1st to 10th	Night	14% 10% 3 6% 4 4 4 3 5% 7% 42%	3611
	11th to 20th	Night	9% 12% 5% 9% 4 4 4 4 5% 6% 38%	3479
	21st to end	Night	12% 9% 6% 9% 5% 4 4 3 4 6% 37%	3817
April	1st to 10th	Night	18% 10% 4 7% 4 3 5% 3 5% 6% 34%	1951
	11th to 20th	Night	19% 8% 3 6% 5% 4 4 3 6% 6% 39%	1687
	21st to end	Night	17% 10% 4 10% 4 4 4 3 5% 6% 34%	1710
May	1st to 10th	Night	15% 8% 3 10% 6% 5% 4 4 5% 6% 36%	2833
	11th to 20th	Night	10% 8% 3 9% 5% 5% 5% 3 6% 8% 38%	2672
	21st to end	Night	14% 7% 2 6% 4 3 4 4 5% 7% 42%	2497
June	1st to 10th	Night	12% 6% 2 6% 5% 5% 5% 6% 6% 7% 40%	1330
	11th to 20th	Night	10% 6% 3 5% 4 4 6% 5% 7% 8% 42%	1330
	21st to end	Night	12% 6% 3 8% 5% 4 6% 4 6% 6% 42%	1330
July	1st to 10th	Night	13% 7% 2 7% 4 3 4 3 6% 8% 43%	2210
	11th to 20th	Night	9% 5% 2 5% 4 3 4 3 6% 8% 50%	2327
	21st to end	Night	8% 6% 1 6% 4 4 5% 4 5% 8% 51%	2828
August	1st to 10th	Night	8% 5% 2 6% 5% 5% 5% 5% 7% 8% 44%	2825
	11th to 20th	Night	13% 6% 2 6% 4 5% 4 4 6% 8% 42%	2785
	21st to end	Night	8% 5% 2 7% 4 4 4 3 5% 7% 51%	3124
September	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 47%	1915
	11th to 20th	Night	13% 5% 2 5% 4 3 3 3 4 8% 51%	2090
	21st to end	Night	17% 9% 3 7% 5% 4 3 3 4 8% 39%	2090
October	1st to 10th	Night	18% 8% 3 8% 4 4 4 2 4 5% 39%	2208
	11th to 20th	Night	22% 11% 3 9% 5% 4 5% 4 5% 6% 26%	2280
	21st to end	Night	24% 15% 4 9% 5% 4 4 3 4 5% 22%	2684
November	1st to 10th	Night	16% 13% 4 8% 7% 5% 4 4 6% 6% 28%	2543
	11th to 20th	Night	16% 16% 6% 11% 7% 5% 5% 4 4 6% 20%	2800
	21st to end	Night	19% 19% 6% 13% 7% 5% 5% 3 4 5% 16%	2800
December	1st to 10th	Night	16% 19% 7% 14% 7% 5% 5% 4 4 5% 15%	4744
	11th to 20th	Night	14% 17% 6% 15% 8% 6% 5% 4 5% 5% 15%	5586
	21st to end	Night	22% 23% 7% 11% 6% 4 5% 3 4 3 11%	7502

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	64% 5% 10% 15% 4 1	3224
	11th to 20th	Day	70% 6% 8% 10% 6% 1	3620
	21st to end	Day	70% 5% 7% 9% 7%	4131
February	1st to 10th	Day	58% 6% 13% 16% 7% 1	1800
	11th to 20th	Day	55% 6% 11% 17% 10% 1	1767
	21st to end	Day	59% 5% 8% 19% 9% 1	1610
March	1st to 10th	Day	48% 4 17% 15% 14% 2	3231
	11th to 20th	Day	51% 6% 10% 24% 8% 2	3480
	21st to end	Day	48% 6% 14% 16% 13% 3	3815
April	1st to 10th	Day	51% 5% 12% 18% 12% 1	2244
	11th to 20th	Day	47% 5% 9% 25% 12% 2	2442
	21st to end	Day	46% 5% 10% 20% 15% 4	2470
May	1st to 10th	Day	40% 5% 10% 26% 17% 2	4120
	11th to 20th	Day	40% 4 13% 25% 17% 2	4211
	21st to end	Day	37% 5% 13% 20% 21% 4	5083
June	1st to 10th	Day	39% 6% 12% 27% 14% 2	2850
	11th to 20th	Day	37% 6% 13% 26% 17% 1	2850
	21st to end	Day	40% 6% 14% 24% 14% 2	2850
July	1st to 10th	Day	41% 6% 14% 25% 13% 1	4686
	11th to 20th	Day	30% 6% 14% 37% 12% 1	4559
	21st to end	Day	30% 4 11% 32% 22%	4580
August	1st to 10th	Day	34% 7% 13% 32% 13% 1	4091
	11th to 20th	Day	37% 6% 17% 27% 12%	4083
	21st to end	Day	34% 7% 15% 33% 10% 1	4531
September	1st to 10th	Day	37% 7% 15% 28% 12% 1	2242
	11th to 20th	Day	35% 5% 17% 31% 11%	2090
	21st to end	Day	44% 6% 17% 24% 9%	2090
October	1st to 10th	Day	37% 4 10% 30% 18%	3270
	11th to 20th	Day	48% 6% 14% 22% 9%	3140
	21st to end	Day	60% 6% 12% 15% 7%	3125
November	1st to 10th	Day	57% 5% 13% 19% 6%	1752
	11th to 20th	Day	63% 7% 13% 12% 5%	1600
	21st to end	Day	71% 6% 11% 9% 2	1600
December	1st to 10th	Day	70% 9% 11% 8% 2	2427
	11th to 20th	Day	70% 7% 11% 10% 2	2621
	21st to end	Day	75% 5% 8% 9% 3	3476
January	1st to 10th	Night	62% 6% 12% 13% 6% 1	6739
	11th to 20th	Night	64% 5% 11% 12% 8%	6360
	21st to end	Night	66% 5% 9% 12% 8% 1	6840
February	1st to 10th	Night	60% 5% 9% 17% 7% 1	2600
	11th to 20th	Night	57% 5% 11% 18% 8% 1	2525
	21st to end	Night	57% 5% 11% 17% 9%	1939
March	1st to 10th	Night	43% 5% 15% 22% 14% 1	3621
	11th to 20th	Night	45% 4 14% 25% 10% 2	3480
	21st to end	Night	47% 5% 11% 22% 13% 2	3817
April	1st to 10th	Night	49% 5% 10% 20% 14% 1	1951
	11th to 20th	Night	45% 4 7% 25% 17% 2	1687
	21st to end	Night	51% 5% 8% 17% 15% 4	1710
May	1st to 10th	Night	48% 6% 9% 23% 13% 2	2840
	11th to 20th	Night	45% 4 8% 26% 15% 2	2673
	21st to end	Night	40% 6% 12% 19% 16% 6%	2498
June	1st to 10th	Night	40% 4 13% 23% 17% 3	1330
	11th to 20th	Night	37% 6% 13% 23% 20% 2	1330
	21st to end	Night	42% 5% 13% 24% 13% 2	1330
July	1st to 10th	Night	39% 5% 15% 23% 15% 3	2175
	11th to 20th	Night	31% 4 14% 36% 14% 1	2285
	21st to end	Night	31% 6% 13% 28% 22%	2738
August	1st to 10th	Night	35% 7% 15% 30% 13% 1	2814
	11th to 20th	Night	37% 9% 13% 27% 13%	2812
	21st to end	Night	32% 6% 13% 32% 15% 1	3124
September	1st to 10th	Night	37% 6% 14% 28% 14% 2	1915
	11th to 20th	Night	33% 5% 16% 34% 11% 1	2090
	21st to end	Night	46% 6% 15% 24% 10%	2090
October	1st to 10th	Night	38% 6% 10% 30% 15%	3689
	11th to 20th	Night	46% 6% 15% 23% 10%	3779
	21st to end	Night	55% 7% 16% 16% 5%	4422
November	1st to 10th	Night	55% 7% 12% 20% 7%	2543
	11th to 20th	Night	64% 6% 13% 12% 5%	2800
	21st to end	Night	69% 6% 12% 10% 2	2800
December	1st to 10th	Night	69% 8% 11% 10% 2	4744
	11th to 20th	Night	67% 6% 10% 9% 6% 1	5585
	21st to end	Night	75% 5% 8% 8% 3	7502

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	22% 14% 32% 22% 7% 3	214
	11th to 20th	Day	20% 10% 36% 24% 9% 1	300
	21st to end	Day	23% 13% 28% 27% 8% 2	330
February	1st to 10th	Day	20% 20% 35% 20% 5% 1	300
	11th to 20th	Day	18% 19% 38% 21% 4	300
	21st to end	Day	19% 25% 32% 22% 3	237
March	1st to 10th	Day	17% 17% 36% 23% 6% 2	329
	11th to 20th	Day	17% 13% 33% 26% 9% 2	460
	21st to end	Day	24% 13% 29% 24% 8% 2	506
April	1st to 10th	Day	21% 12% 27% 28% 11% 1	460
	11th to 20th	Day	26% 11% 27% 21% 10% 4	452
	21st to end	Day	25% 10% 28% 23% 12% 2	460
May	1st to 10th	Day	20% 6% 32% 28% 11% 3	463
	11th to 20th	Day	15% 8% 29% 28% 17% 4	487
	21st to end	Day	12% 6% 28% 34% 16% 3	671
June	1st to 10th	Day	14% 7% 28% 35% 14% 2	680
	11th to 20th	Day	14% 7% 29% 35% 13% 3	680
	21st to end	Day	15% 9% 25% 33% 14% 4	680
July	1st to 10th	Day	9% 5% 27% 38% 19% 3	671
	11th to 20th	Day	11% 6% 28% 34% 17% 4	668
	21st to end	Day	12% 6% 25% 35% 17% 5%	692
August	1st to 10th	Day	13% 6% 19% 34% 23% 6%	486
	11th to 20th	Day	11% 3 18% 32% 24% 11%	479
	21st to end	Day	13% 6% 26% 28% 19% 7%	539
September	1st to 10th	Day	16% 9% 22% 26% 21% 6%	490
	11th to 20th	Day	15% 5% 20% 29% 24% 6%	490
	21st to end	Day	22% 11% 19% 27% 19% 3	490
October	1st to 10th	Day	20% 17% 23% 21% 17% 2	490
	11th to 20th	Day	21% 18% 33% 21% 6% 1	490
	21st to end	Day	27% 17% 33% 18% 4	362
November	1st to 10th	Day	26% 15% 35% 19% 5% 1	295
	11th to 20th	Day	24% 21% 31% 24% 2	200
	21st to end	Day	26% 26% 28% 17% 5%	200
December	1st to 10th	Day	27% 13% 33% 18% 7% 3	200
	11th to 20th	Day	27% 22% 34% 16% 3	200
	21st to end	Day	33% 17% 34% 11% 4	220
January	1st to 10th	Night	21% 13% 36% 23% 7% 1	1000
	11th to 20th	Night	22% 13% 32% 23% 9% 1	1000
	21st to end	Night	20% 9% 31% 29% 9% 1	1035
February	1st to 10th	Night	19% 14% 38% 23% 7%	800
	11th to 20th	Night	19% 13% 33% 26% 9% 1	783
	21st to end	Night	21% 12% 38% 24% 5% 1	647
March	1st to 10th	Night	16% 11% 38% 27% 6% 1	760
	11th to 20th	Night	18% 12% 36% 25% 9% 1	760
	21st to end	Night	17% 10% 32% 32% 9% 1	836
April	1st to 10th	Night	22% 10% 34% 27% 7%	670
	11th to 20th	Night	23% 10% 27% 27% 12% 1	563
	21st to end	Night	21% 10% 28% 27% 13% 1	570
May	1st to 10th	Night	15% 4 28% 38% 13% 2	570
	11th to 20th	Night	17% 6% 27% 35% 15% 1	486
	21st to end	Night	15% 6% 25% 36% 18% 1	411
June	1st to 10th	Night	14% 5% 29% 37% 14%	380
	11th to 20th	Night	12% 7% 22% 39% 18% 2	380
	21st to end	Night	16% 4 22% 40% 16% 2	380
July	1st to 10th	Night	9% 4 22% 47% 18% 1	370
	11th to 20th	Night	9% 2 22% 39% 25% 3	433
	21st to end	Night	10% 4 21% 38% 24% 2	624
August	1st to 10th	Night	12% 3 21% 39% 22% 3	567
	11th to 20th	Night	12% 4 18% 29% 33% 4	564
	21st to end	Night	12% 4 22% 36% 21% 4	627
September	1st to 10th	Night	16% 7% 21% 33% 17% 6%	687
	11th to 20th	Night	13% 6% 22% 32% 21% 6%	760
	21st to end	Night	20% 8% 23% 28% 17% 4	760
October	1st to 10th	Night	22% 11% 26% 25% 15% 2	760
	11th to 20th	Night	29% 12% 27% 24% 7% 1	760
	21st to end	Night	31% 12% 30% 22% 4 1	836
November	1st to 10th	Night	25% 14% 29% 24% 8%	780
	11th to 20th	Night	24% 19% 30% 19% 8%	800
	21st to end	Night	29% 15% 34% 18% 4	800
December	1st to 10th	Night	27% 17% 31% 18% 6% 1	899
	11th to 20th	Night	25% 18% 37% 15% 5% 1	1000
	21st to end	Night	32% 13% 31% 18% 6%	1100

Page generated at 2025-02-22 06:51:34. Version ac07

Copyright © 2025 Attilla Danko.