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 2024-02-05.

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	14% 10% 4 7% 6% 3 5% 4 5% 7% 35%	77860
	Night	15% 12% 5% 8% 7% 4 5% 5% 5% 6% 29%	81024
Transparency	Day	49% 6% 12% 21% 11% 1	77559
	Night	55% 5% 12% 18% 9% 1	80860
Seeing	Day	18% 10% 28% 28% 14% 3	14278
	Night	20% 10% 29% 28% 12% 2	23774

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% 20% 11% 12% 7% 4 4 4 4 6% 16%	2245
	11th to 20th	Day	10% 15% 7% 15% 12% 7% 7% 4 3 4 16%	2530
	21st to end	Day	15% 19% 9% 14% 9% 3 5% 5% 4 4 14%	2880
February	1st to 10th	Day	10% 14% 6% 11% 9% 4 5% 5% 5% 7% 26%	1656
	11th to 20th	Day	11% 14% 5% 9% 7% 3 6% 4 5% 6% 29%	1577
	21st to end	Day	12% 15% 6% 10% 7% 4 5% 4 5% 5% 27%	1480
March	1st to 10th	Day	12% 11% 5% 5% 5% 3 5% 4 4 6% 40%	1852
	11th to 20th	Day	11% 10% 4 9% 6% 3 3 4 4 6% 40%	1980
	21st to end	Day	16% 7% 3 7% 5% 2 5% 5% 5% 7% 39%	2178
April	1st to 10th	Day	17% 10% 4 7% 6% 3 4 5% 5% 7% 32%	2125
	11th to 20th	Day	17% 8% 3 7% 5% 2 5% 3 6% 6% 37%	2312
	21st to end	Day	20% 7% 3 6% 5% 3 4 4 5% 8% 36%	2340
May	1st to 10th	Day	15% 7% 3 6% 4 3 5% 4 5% 7% 41%	2340
	11th to 20th	Day	14% 6% 3 5% 5% 3 4 4 6% 7% 42%	2371
	21st to end	Day	11% 5% 2 5% 5% 3 4 4 6% 8% 46%	2859
June	1st to 10th	Day	13% 5% 3 4 5% 3 5% 5% 6% 8% 43%	2700
	11th to 20th	Day	11% 5% 2 5% 6% 3 5% 5% 7% 8% 43%	2700
	21st to end	Day	11% 7% 3 6% 5% 3 4 5% 5% 8% 43%	2700
July	1st to 10th	Day	8% 4 2 3 4 2 4 5% 6% 9% 52%	2700
	11th to 20th	Day	10% 5% 2 5% 5% 3 4 4 6% 7% 48%	2636
	21st to end	Day	10% 5% 2 4 4 3 4 4 5% 8% 50%	2699
August	1st to 10th	Day	10% 6% 2 4 5% 3 4 4 6% 9% 47%	2327
	11th to 20th	Day	10% 5% 2 4 5% 3 4 5% 6% 9% 47%	2303
	21st to end	Day	10% 6% 3 5% 4 3 5% 5% 6% 7% 46%	2574
September	1st to 10th	Day	13% 6% 2 5% 5% 2 4 5% 6% 8% 43%	2125
	11th to 20th	Day	13% 5% 2 5% 4 3 5% 5% 6% 9% 45%	1980
	21st to end	Day	17% 9% 3 5% 5% 2 5% 4 5% 8% 37%	1980
October	1st to 10th	Day	18% 8% 4 7% 7% 3 4 4 4 6% 36%	1868
	11th to 20th	Day	21% 12% 3 7% 7% 4 5% 5% 4 7% 24%	1800
	21st to end	Day	23% 12% 5% 8% 8% 3 4 5% 5% 6% 21%	1813
November	1st to 10th	Day	16% 12% 5% 8% 8% 3 5% 5% 4 7% 27%	1663
	11th to 20th	Day	14% 15% 7% 10% 8% 4 5% 5% 5% 7% 20%	1520
	21st to end	Day	21% 20% 5% 10% 8% 3 5% 4 4 6% 14%	1520
December	1st to 10th	Day	14% 20% 9% 12% 8% 4 6% 4 5% 5% 14%	1425
	11th to 20th	Day	17% 17% 6% 11% 8% 4 7% 5% 4 5% 16%	1671
	21st to end	Day	24% 22% 6% 10% 7% 3 4 3 3 4 13%	2431
January	1st to 10th	Night	14% 16% 7% 14% 8% 4 5% 5% 5% 5% 17%	4707
	11th to 20th	Night	12% 14% 6% 13% 11% 5% 6% 5% 5% 6% 18%	4440
	21st to end	Night	15% 19% 7% 12% 8% 4 4 5% 4 5% 18%	4784
February	1st to 10th	Night	11% 14% 5% 11% 7% 4 6% 5% 6% 5% 25%	2399
	11th to 20th	Night	11% 14% 6% 10% 8% 4 6% 4 6% 6% 26%	2264
	21st to end	Night	14% 15% 6% 8% 8% 3 6% 5% 5% 5% 26%	1776
March	1st to 10th	Night	12% 9% 3 6% 7% 3 5% 5% 5% 7% 39%	2094
	11th to 20th	Night	13% 10% 4 7% 5% 3 4 5% 4 5% 38%	1979
	21st to end	Night	14% 9% 3 7% 6% 3 5% 4 5% 6% 39%	2178
April	1st to 10th	Night	19% 9% 4 6% 5% 2 5% 4 5% 6% 34%	1849
	11th to 20th	Night	18% 7% 3 5% 4 3 5% 4 6% 6% 40%	1597
	21st to end	Night	17% 9% 4 8% 5% 3 4 4 5% 6% 34%	1620
May	1st to 10th	Night	11% 7% 4 8% 7% 5% 6% 5% 6% 7% 35%	1620
	11th to 20th	Night	13% 8% 4 6% 7% 4 5% 4 5% 6% 38%	1522
	21st to end	Night	11% 6% 2 6% 5% 3 4 5% 6% 7% 45%	1413
June	1st to 10th	Night	13% 5% 2 5% 5% 3 5% 7% 6% 8% 42%	1260
	11th to 20th	Night	10% 6% 3 5% 4 2 7% 6% 7% 8% 42%	1260
	21st to end	Night	12% 5% 3 7% 5% 3 5% 5% 5% 7% 43%	1260
July	1st to 10th	Night	9% 4 2 5% 4 2 4 4 5% 8% 52%	1260
	11th to 20th	Night	7% 5% 3 4 5% 4 5% 5% 6% 9% 47%	1321
	21st to end	Night	8% 5% 3 5% 5% 3 5% 5% 5% 8% 48%	1616
August	1st to 10th	Night	8% 4 2 4 5% 3 5% 5% 5% 8% 49%	1611
	11th to 20th	Night	10% 5% 2 5% 6% 4 5% 6% 6% 7% 45%	1598
	21st to end	Night	11% 6% 2 6% 5% 3 4 5% 5% 7% 46%	1782
September	1st to 10th	Night	13% 6% 2 5% 5% 3 5% 4 5% 6% 46%	1813
	11th to 20th	Night	13% 5% 2 4 4 3 4 4 4 8% 49%	1980
	21st to end	Night	17% 9% 3 6% 6% 3 3 4 4 8% 38%	1980
October	1st to 10th	Night	19% 8% 3 7% 5% 3 5% 3 4 5% 37%	2091
	11th to 20th	Night	24% 11% 3 8% 6% 3 5% 5% 4 5% 25%	2160
	21st to end	Night	25% 14% 4 8% 6% 3 4 4 4 5% 22%	2542
November	1st to 10th	Night	16% 12% 5% 7% 7% 4 5% 5% 5% 6% 28%	2412
	11th to 20th	Night	16% 15% 6% 10% 8% 4 6% 5% 4 6% 20%	2660
	21st to end	Night	19% 17% 6% 11% 8% 4 5% 4 4 5% 17%	2660
December	1st to 10th	Night	17% 18% 8% 12% 8% 4 6% 4 3 4 15%	2754
	11th to 20th	Night	16% 15% 6% 10% 8% 5% 6% 5% 5% 5% 19%	3526
	21st to end	Night	23% 22% 7% 9% 8% 3 4 4 3 4 13%	5236

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	70% 5% 11% 11% 3	2246
	11th to 20th	Day	73% 5% 9% 9% 3 1	2530
	21st to end	Day	74% 5% 8% 8% 5% 1	2880
February	1st to 10th	Day	58% 6% 13% 15% 7% 1	1656
	11th to 20th	Day	55% 6% 11% 18% 10% 1	1586
	21st to end	Day	60% 5% 8% 18% 9% 1	1480
March	1st to 10th	Day	45% 4 15% 16% 16% 3	1855
	11th to 20th	Day	47% 5% 10% 26% 10% 3	1980
	21st to end	Day	46% 4 12% 21% 13% 3	2178
April	1st to 10th	Day	51% 5% 12% 18% 12% 1	2125
	11th to 20th	Day	47% 5% 9% 25% 12% 2	2312
	21st to end	Day	46% 5% 10% 20% 15% 4	2340
May	1st to 10th	Day	43% 5% 10% 25% 14% 3	2340
	11th to 20th	Day	41% 5% 10% 22% 20% 2	2375
	21st to end	Day	35% 6% 16% 24% 15% 2	2859
June	1st to 10th	Day	38% 5% 13% 27% 15% 2	2700
	11th to 20th	Day	37% 6% 13% 27% 16% 1	2700
	21st to end	Day	39% 6% 14% 25% 14% 2	2700
July	1st to 10th	Day	28% 7% 14% 31% 18% 2	2626
	11th to 20th	Day	34% 7% 12% 32% 14% 1	2555
	21st to end	Day	34% 5% 15% 30% 16% 1	2549
August	1st to 10th	Day	35% 6% 16% 28% 13% 1	2314
	11th to 20th	Day	34% 7% 18% 27% 13% 1	2303
	21st to end	Day	37% 7% 15% 27% 13% 1	2574
September	1st to 10th	Day	38% 7% 15% 26% 12% 1	2125
	11th to 20th	Day	36% 5% 18% 31% 9% 1	1980
	21st to end	Day	45% 6% 18% 24% 8%	1980
October	1st to 10th	Day	50% 5% 10% 24% 10%	1868
	11th to 20th	Day	59% 7% 13% 17% 5%	1800
	21st to end	Day	62% 6% 11% 12% 7% 1	1813
November	1st to 10th	Day	56% 6% 13% 19% 6%	1663
	11th to 20th	Day	63% 8% 13% 11% 5%	1520
	21st to end	Day	72% 5% 11% 9% 2	1520
December	1st to 10th	Day	72% 6% 10% 9% 4	1425
	11th to 20th	Day	68% 6% 10% 12% 3	1671
	21st to end	Day	74% 6% 8% 8% 4	2431
January	1st to 10th	Night	68% 5% 11% 9% 6%	4707
	11th to 20th	Night	67% 5% 13% 10% 4	4440
	21st to end	Night	69% 4 9% 12% 5%	4784
February	1st to 10th	Night	61% 5% 9% 17% 7% 1	2399
	11th to 20th	Night	58% 5% 11% 18% 8% 1	2266
	21st to end	Night	59% 5% 10% 17% 9%	1776
March	1st to 10th	Night	44% 6% 13% 20% 15% 2	2104
	11th to 20th	Night	47% 5% 12% 22% 12% 2	1980
	21st to end	Night	45% 5% 11% 19% 16% 4	2178
April	1st to 10th	Night	49% 5% 10% 20% 14% 1	1849
	11th to 20th	Night	44% 5% 8% 25% 17% 2	1597
	21st to end	Night	52% 5% 8% 18% 15% 4	1620
May	1st to 10th	Night	47% 6% 10% 21% 13% 3	1620
	11th to 20th	Night	47% 4 6% 25% 15% 3	1523
	21st to end	Night	37% 7% 13% 23% 16% 5%	1414
June	1st to 10th	Night	39% 4 13% 24% 17% 3	1260
	11th to 20th	Night	37% 6% 12% 24% 19% 2	1260
	21st to end	Night	41% 6% 13% 25% 14% 2	1260
July	1st to 10th	Night	30% 5% 14% 28% 20% 3	1225
	11th to 20th	Night	34% 5% 13% 31% 15% 1	1279
	21st to end	Night	34% 6% 16% 27% 17% 1	1526
August	1st to 10th	Night	32% 6% 19% 30% 10% 2	1600
	11th to 20th	Night	35% 8% 14% 29% 12% 1	1598
	21st to end	Night	38% 6% 15% 26% 13% 2	1782
September	1st to 10th	Night	36% 6% 15% 27% 14% 2	1813
	11th to 20th	Night	35% 5% 16% 34% 9%	1980
	21st to end	Night	46% 6% 15% 24% 8%	1980
October	1st to 10th	Night	49% 6% 12% 22% 11%	2091
	11th to 20th	Night	59% 6% 11% 18% 5%	2160
	21st to end	Night	64% 5% 9% 14% 6% 1	2542
November	1st to 10th	Night	55% 7% 11% 19% 7%	2412
	11th to 20th	Night	65% 7% 13% 11% 5%	2660
	21st to end	Night	69% 6% 12% 10% 2	2660
December	1st to 10th	Night	72% 6% 8% 11% 2	2754
	11th to 20th	Night	65% 6% 12% 10% 6% 1	3525
	21st to end	Night	75% 4 9% 8% 4	5236

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% 15% 31% 22% 7% 3	192
	11th to 20th	Day	20% 10% 36% 24% 9% 1	270
	21st to end	Day	24% 12% 26% 29% 8% 1	297
February	1st to 10th	Day	19% 17% 36% 21% 6% 1	252
	11th to 20th	Day	19% 16% 40% 20% 5%	240
	21st to end	Day	20% 27% 30% 21% 2	198
March	1st to 10th	Day	18% 18% 34% 22% 7% 2	295
	11th to 20th	Day	18% 13% 32% 26% 9% 2	420
	21st to end	Day	26% 11% 28% 25% 8% 2	462
April	1st to 10th	Day	21% 10% 27% 29% 12% 1	420
	11th to 20th	Day	25% 10% 27% 23% 11% 4	412
	21st to end	Day	25% 9% 28% 23% 12% 2	420
May	1st to 10th	Day	20% 5% 32% 28% 12% 3	423
	11th to 20th	Day	16% 7% 29% 27% 17% 4	447
	21st to end	Day	12% 5% 28% 34% 17% 4	619
June	1st to 10th	Day	14% 6% 29% 35% 14% 2	630
	11th to 20th	Day	14% 6% 29% 35% 13% 3	630
	21st to end	Day	14% 7% 25% 35% 15% 4	630
July	1st to 10th	Day	8% 4 26% 39% 20% 3	621
	11th to 20th	Day	11% 5% 26% 34% 18% 5%	618
	21st to end	Day	12% 6% 25% 34% 18% 5%	640
August	1st to 10th	Day	14% 4 18% 34% 24% 7%	446
	11th to 20th	Day	11% 3 17% 33% 25% 11%	439
	21st to end	Day	13% 5% 26% 28% 20% 8%	495
September	1st to 10th	Day	16% 7% 22% 26% 23% 7%	450
	11th to 20th	Day	16% 6% 22% 30% 21% 5%	450
	21st to end	Day	22% 11% 18% 26% 18% 4	450
October	1st to 10th	Day	21% 14% 23% 22% 17% 2	450
	11th to 20th	Day	22% 18% 31% 22% 6% 1	450
	21st to end	Day	27% 16% 34% 19% 4	328
November	1st to 10th	Day	25% 15% 34% 20% 5% 1	266
	11th to 20th	Day	22% 22% 31% 24% 2	180
	21st to end	Day	26% 23% 28% 18% 4	180
December	1st to 10th	Day	27% 13% 33% 18% 7% 3	180
	11th to 20th	Day	26% 22% 33% 16% 3	180
	21st to end	Day	32% 18% 35% 11% 3 1	198
January	1st to 10th	Night	21% 13% 35% 23% 7% 1	950
	11th to 20th	Night	23% 12% 32% 23% 9% 1	950
	21st to end	Night	21% 9% 31% 29% 10% 1	984
February	1st to 10th	Night	19% 12% 38% 23% 7%	739
	11th to 20th	Night	19% 12% 32% 27% 10% 1	703
	21st to end	Night	22% 11% 36% 24% 5% 1	592
March	1st to 10th	Night	16% 11% 37% 28% 7% 1	720
	11th to 20th	Night	18% 11% 36% 25% 9% 1	720
	21st to end	Night	18% 8% 31% 33% 9% 1	792
April	1st to 10th	Night	22% 9% 34% 27% 7%	635
	11th to 20th	Night	22% 8% 27% 28% 13% 1	533
	21st to end	Night	21% 9% 29% 28% 13% 1	540
May	1st to 10th	Night	14% 3 28% 39% 13% 2	540
	11th to 20th	Night	18% 6% 26% 34% 16% 1	461
	21st to end	Night	15% 5% 25% 37% 18% 1	389
June	1st to 10th	Night	14% 4 30% 38% 14%	360
	11th to 20th	Night	13% 6% 21% 39% 19% 2	360
	21st to end	Night	14% 3 22% 41% 17% 2	360
July	1st to 10th	Night	9% 3 21% 48% 18% 1	350
	11th to 20th	Night	9% 1 22% 38% 26% 3	409
	21st to end	Night	10% 4 22% 38% 23% 2	591
August	1st to 10th	Night	12% 2 21% 39% 23% 3	537
	11th to 20th	Night	12% 4 17% 29% 34% 4	534
	21st to end	Night	13% 4 22% 36% 21% 4	594
September	1st to 10th	Night	15% 7% 21% 34% 17% 6%	650
	11th to 20th	Night	14% 6% 24% 32% 19% 6%	720
	21st to end	Night	20% 8% 23% 28% 17% 4	720
October	1st to 10th	Night	22% 9% 25% 26% 16% 2	720
	11th to 20th	Night	30% 12% 27% 24% 7% 1	720
	21st to end	Night	32% 11% 29% 22% 4 1	792
November	1st to 10th	Night	24% 14% 29% 24% 8%	740
	11th to 20th	Night	24% 18% 30% 20% 8%	760
	21st to end	Night	28% 14% 34% 19% 4	760
December	1st to 10th	Night	27% 18% 31% 18% 6% 1	854
	11th to 20th	Night	25% 18% 37% 14% 5% 1	950
	21st to end	Night	31% 14% 31% 18% 5%	1045

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