Fancy Gap
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fancy Gap clear sky chart from 2005-11-06 to 2024-02-15.

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	15% 6% 2 5% 5% 3 5% 5% 6% 8% 40%	78731
	Night	16% 5% 2 4 4 3 4 4 5% 7% 44%	80357
Transparency	Day	42% 8% 12% 20% 15% 3	78453
	Night	39% 7% 12% 21% 17% 4	80154
Seeing	Day	20% 16% 25% 21% 13% 5%	14208
	Night	18% 14% 25% 25% 15% 2	24389

By Month

Percentage Cloud Cover SE (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	17% 5% 2 4 3 2 4 4 4 7% 48%	2836
	11th to 20th	Day	14% 6% 2 5% 6% 3 4 4 4 5% 46%	2840
	21st to end	Day	24% 6% 2 5% 4 3 4 3 4 6% 40%	3124
February	1st to 10th	Day	13% 7% 2 5% 6% 4 4 5% 6% 7% 42%	1710
	11th to 20th	Day	19% 8% 3 5% 4 3 5% 3 5% 6% 40%	1707
	21st to end	Day	21% 6% 3 6% 4 2 5% 4 4 6% 39%	1523
March	1st to 10th	Day	14% 5% 2 4 3 2 4 4 5% 7% 48%	1980
	11th to 20th	Day	19% 6% 3 5% 5% 3 4 4 6% 7% 38%	1980
	21st to end	Day	19% 8% 3 5% 5% 3 5% 4 5% 6% 38%	2178
April	1st to 10th	Day	11% 4 2 4 4 3 5% 5% 5% 9% 48%	2006
	11th to 20th	Day	16% 5% 3 4 4 3 5% 4 5% 8% 43%	2134
	21st to end	Day	16% 6% 3 5% 5% 4 5% 4 5% 7% 40%	2314
May	1st to 10th	Day	14% 5% 3 6% 6% 3 6% 6% 7% 8% 37%	2340
	11th to 20th	Day	17% 6% 3 6% 6% 4 6% 6% 5% 8% 33%	2301
	21st to end	Day	16% 5% 2 5% 6% 4 6% 5% 7% 9% 35%	2531
June	1st to 10th	Day	12% 6% 3 5% 6% 4 7% 6% 6% 9% 37%	2340
	11th to 20th	Day	10% 5% 2 5% 7% 5% 7% 7% 7% 10% 36%	2340
	21st to end	Day	9% 5% 3 5% 7% 4 6% 8% 7% 10% 36%	2340
July	1st to 10th	Day	10% 5% 2 7% 8% 5% 7% 7% 8% 10% 30%	2340
	11th to 20th	Day	8% 5% 3 7% 7% 5% 7% 8% 8% 11% 31%	2340
	21st to end	Day	11% 6% 3 8% 7% 6% 8% 7% 8% 8% 29%	2547
August	1st to 10th	Day	15% 5% 2 6% 8% 5% 6% 7% 7% 11% 30%	2327
	11th to 20th	Day	12% 6% 3 7% 7% 5% 7% 7% 8% 9% 29%	2303
	21st to end	Day	11% 6% 2 5% 6% 4 7% 7% 6% 10% 35%	2424
September	1st to 10th	Day	13% 5% 2 5% 5% 3 4 5% 6% 8% 42%	2061
	11th to 20th	Day	17% 5% 2 6% 6% 3 4 5% 6% 7% 39%	1980
	21st to end	Day	22% 6% 3 5% 5% 3 4 5% 5% 6% 37%	1980
October	1st to 10th	Day	15% 5% 2 5% 4 2 4 4 4 7% 48%	1846
	11th to 20th	Day	16% 4 2 4 3 3 3 5% 4 6% 50%	1800
	21st to end	Day	16% 4 2 5% 4 2 2 3 3 5% 52%	1980
November	1st to 10th	Day	13% 5% 2 3 4 2 4 3 4 5% 55%	1857
	11th to 20th	Day	14% 4 2 4 4 2 5% 3 4 6% 52%	1725
	21st to end	Day	15% 5% 2 5% 4 2 3 4 5% 7% 49%	1710
December	1st to 10th	Day	19% 8% 3 5% 5% 3 4 5% 5% 6% 38%	1710
	11th to 20th	Day	16% 4 2 3 3 3 4 4 4 6% 52%	2153
	21st to end	Day	21% 7% 2 5% 4 3 5% 5% 6% 7% 35%	3124
January	1st to 10th	Night	15% 6% 2 4 4 2 4 4 5% 6% 48%	4109
	11th to 20th	Night	15% 6% 3 6% 4 2 4 4 4 5% 48%	4120
	21st to end	Night	24% 7% 2 3 3 2 4 4 4 5% 41%	4532
February	1st to 10th	Night	14% 7% 3 4 4 3 5% 4 5% 7% 44%	2470
	11th to 20th	Night	20% 6% 3 5% 4 3 4 4 4 6% 42%	2230
	21st to end	Night	17% 6% 3 5% 5% 2 5% 5% 6% 7% 40%	1732
March	1st to 10th	Night	14% 4 2 5% 3 3 3 4 6% 6% 50%	1980
	11th to 20th	Night	19% 5% 2 5% 5% 3 5% 5% 5% 7% 40%	1980
	21st to end	Night	17% 6% 2 4 5% 4 4 4 5% 6% 42%	2178
April	1st to 10th	Night	14% 6% 2 5% 4 3 3 4 5% 8% 45%	1954
	11th to 20th	Night	16% 5% 2 4 4 3 4 4 5% 8% 46%	1775
	21st to end	Night	16% 5% 2 4 4 2 5% 4 5% 7% 47%	1660
May	1st to 10th	Night	13% 6% 2 5% 6% 2 4 4 5% 8% 44%	1620
	11th to 20th	Night	16% 7% 3 6% 4 3 4 5% 5% 8% 38%	1592
	21st to end	Night	16% 5% 2 6% 5% 3 3 5% 6% 10% 39%	1744
June	1st to 10th	Night	11% 5% 2 4 5% 3 5% 6% 6% 10% 42%	1620
	11th to 20th	Night	12% 5% 3 5% 5% 3 4 4 7% 10% 44%	1620
	21st to end	Night	8% 4 2 4 6% 4 5% 5% 7% 11% 44%	1620
July	1st to 10th	Night	10% 5% 2 5% 6% 3 6% 6% 7% 10% 40%	1620
	11th to 20th	Night	7% 4 2 4 5% 2 6% 8% 8% 13% 42%	1620
	21st to end	Night	6% 5% 2 5% 6% 4 6% 7% 8% 11% 38%	1771
August	1st to 10th	Night	15% 5% 2 5% 6% 4 6% 6% 7% 11% 34%	1611
	11th to 20th	Night	14% 6% 3 6% 6% 3 5% 5% 6% 9% 37%	1598
	21st to end	Night	11% 5% 2 6% 6% 4 5% 6% 6% 9% 40%	1912
September	1st to 10th	Night	11% 4 2 5% 5% 4 4 5% 6% 7% 47%	1895
	11th to 20th	Night	15% 7% 2 6% 6% 4 3 4 4 7% 42%	1980
	21st to end	Night	19% 7% 3 5% 5% 3 4 4 5% 6% 39%	1980
October	1st to 10th	Night	15% 5% 2 5% 4 2 5% 4 4 6% 48%	2112
	11th to 20th	Night	15% 5% 2 4 4 2 4 4 4 6% 51%	2160
	21st to end	Night	15% 4 2 4 3 1 3 3 3 5% 55%	2376
November	1st to 10th	Night	16% 5% 2 5% 3 2 3 3 3 5% 53%	2221
	11th to 20th	Night	15% 3 1 3 3 2 3 4 4 6% 54%	2451
	21st to end	Night	15% 4 1 4 4 2 4 5% 6% 7% 48%	2470
December	1st to 10th	Night	19% 6% 2 5% 4 3 4 3 5% 6% 42%	2470
	11th to 20th	Night	17% 5% 2 4 4 2 3 5% 5% 7% 47%	3042
	21st to end	Night	23% 6% 2 4 4 2 5% 5% 5% 8% 36%	4532

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	36% 5% 10% 24% 22% 4	2837
	11th to 20th	Day	39% 6% 8% 19% 25% 3	2840
	21st to end	Day	47% 5% 8% 18% 19% 3	3124
February	1st to 10th	Day	42% 7% 11% 19% 18% 3	1710
	11th to 20th	Day	46% 5% 9% 21% 16% 4	1716
	21st to end	Day	47% 6% 11% 14% 15% 6%	1523
March	1st to 10th	Day	36% 6% 10% 23% 20% 6%	1980
	11th to 20th	Day	46% 7% 10% 18% 15% 5%	1980
	21st to end	Day	48% 6% 10% 21% 12% 3	2178
April	1st to 10th	Day	33% 8% 12% 24% 17% 6%	2006
	11th to 20th	Day	39% 6% 12% 20% 18% 5%	2134
	21st to end	Day	44% 9% 11% 22% 12% 3	2314
May	1st to 10th	Day	43% 10% 15% 16% 12% 3	2340
	11th to 20th	Day	48% 10% 14% 19% 8% 2	2305
	21st to end	Day	43% 11% 15% 23% 7%	2531
June	1st to 10th	Day	43% 10% 16% 21% 10% 1	2340
	11th to 20th	Day	40% 12% 15% 18% 13% 2	2340
	21st to end	Day	41% 11% 17% 19% 12% 2	2340
July	1st to 10th	Day	45% 13% 15% 16% 9% 2	2275
	11th to 20th	Day	42% 15% 18% 14% 10% 1	2271
	21st to end	Day	47% 13% 15% 17% 7% 1	2405
August	1st to 10th	Day	47% 13% 14% 19% 6% 1	2314
	11th to 20th	Day	45% 14% 16% 17% 8%	2303
	21st to end	Day	41% 12% 16% 19% 10% 3	2424
September	1st to 10th	Day	39% 9% 13% 20% 16% 3	2061
	11th to 20th	Day	43% 8% 11% 21% 15% 2	1980
	21st to end	Day	48% 7% 11% 17% 15% 2	1980
October	1st to 10th	Day	37% 7% 10% 23% 19% 4	1846
	11th to 20th	Day	34% 6% 11% 23% 20% 6%	1800
	21st to end	Day	36% 4 8% 26% 20% 6%	1980
November	1st to 10th	Day	33% 5% 9% 21% 26% 6%	1857
	11th to 20th	Day	35% 5% 8% 20% 25% 6%	1725
	21st to end	Day	36% 6% 10% 21% 25% 4	1710
December	1st to 10th	Day	47% 7% 10% 17% 16% 4	1710
	11th to 20th	Day	34% 5% 11% 20% 24% 6%	2150
	21st to end	Day	45% 6% 11% 21% 16% 2	3124
January	1st to 10th	Night	36% 5% 13% 21% 21% 4	4109
	11th to 20th	Night	39% 6% 10% 16% 23% 6%	4120
	21st to end	Night	47% 5% 7% 18% 20% 3	4532
February	1st to 10th	Night	39% 6% 11% 23% 18% 2	2470
	11th to 20th	Night	46% 5% 9% 19% 16% 5%	2232
	21st to end	Night	43% 8% 10% 20% 14% 5%	1732
March	1st to 10th	Night	36% 6% 10% 23% 20% 5%	1980
	11th to 20th	Night	44% 7% 11% 22% 14% 2	1980
	21st to end	Night	43% 8% 10% 20% 15% 3	2178
April	1st to 10th	Night	37% 7% 12% 22% 18% 4	1954
	11th to 20th	Night	37% 6% 11% 20% 19% 6%	1775
	21st to end	Night	38% 7% 12% 27% 14% 2	1660
May	1st to 10th	Night	39% 8% 15% 24% 13% 1	1620
	11th to 20th	Night	43% 10% 15% 22% 9% 1	1593
	21st to end	Night	41% 9% 19% 24% 7% 1	1745
June	1st to 10th	Night	36% 11% 17% 24% 11% 1	1620
	11th to 20th	Night	35% 10% 19% 23% 12% 1	1620
	21st to end	Night	32% 12% 18% 22% 13% 3	1620
July	1st to 10th	Night	37% 13% 15% 20% 11% 4	1575
	11th to 20th	Night	31% 13% 23% 20% 10% 3	1566
	21st to end	Night	33% 13% 21% 23% 8%	1672
August	1st to 10th	Night	42% 13% 16% 19% 10%	1600
	11th to 20th	Night	42% 11% 16% 20% 10% 1	1598
	21st to end	Night	38% 10% 18% 22% 9% 2	1912
September	1st to 10th	Night	34% 11% 16% 20% 16% 4	1895
	11th to 20th	Night	41% 8% 12% 21% 18% 1	1980
	21st to end	Night	45% 7% 10% 19% 16% 2	1980
October	1st to 10th	Night	37% 7% 10% 22% 20% 3	2112
	11th to 20th	Night	35% 6% 9% 25% 20% 5%	2160
	21st to end	Night	32% 5% 8% 24% 24% 7%	2376
November	1st to 10th	Night	36% 4 9% 20% 24% 7%	2221
	11th to 20th	Night	33% 5% 9% 20% 24% 8%	2451
	21st to end	Night	34% 6% 9% 25% 22% 5%	2470
December	1st to 10th	Night	43% 6% 9% 22% 16% 4	2470
	11th to 20th	Night	38% 6% 10% 18% 22% 6%	3044
	21st to end	Night	45% 6% 12% 19% 17% 1	4532

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	33% 31% 26% 9% 2	270
	11th to 20th	Day	34% 33% 27% 5% 1	270
	21st to end	Day	31% 33% 29% 5% 2	297
February	1st to 10th	Day	27% 34% 26% 11% 2	270
	11th to 20th	Day	46% 27% 24% 2 1	252
	21st to end	Day	34% 28% 28% 7% 2	241
March	1st to 10th	Day	25% 29% 30% 14% 3	420
	11th to 20th	Day	28% 30% 26% 12% 3 1	420
	21st to end	Day	28% 23% 29% 15% 4	462
April	1st to 10th	Day	22% 28% 27% 15% 8% 1	420
	11th to 20th	Day	24% 19% 25% 20% 9% 2	412
	21st to end	Day	23% 20% 29% 17% 10% 3	420
May	1st to 10th	Day	20% 18% 36% 14% 9% 3	423
	11th to 20th	Day	21% 12% 29% 22% 11% 5%	447
	21st to end	Day	20% 7% 21% 26% 18% 7%	485
June	1st to 10th	Day	14% 8% 28% 29% 14% 7%	450
	11th to 20th	Day	10% 11% 23% 30% 19% 7%	450
	21st to end	Day	12% 7% 28% 36% 12% 6%	450
July	1st to 10th	Day	11% 3 17% 32% 24% 12%	445
	11th to 20th	Day	6% 4 19% 31% 29% 11%	444
	21st to end	Day	11% 5% 19% 29% 23% 13%	488
August	1st to 10th	Day	17% 6% 22% 22% 19% 15%	446
	11th to 20th	Day	12% 4 21% 27% 21% 15%	439
	21st to end	Day	12% 3 17% 30% 21% 17%	495
September	1st to 10th	Day	12% 5% 18% 27% 27% 11%	450
	11th to 20th	Day	15% 7% 15% 29% 24% 10%	450
	21st to end	Day	21% 13% 22% 26% 15% 4	450
October	1st to 10th	Day	18% 11% 23% 24% 19% 5%	450
	11th to 20th	Day	16% 18% 27% 22% 16% 2	450
	21st to end	Day	23% 15% 29% 23% 8% 2	495
November	1st to 10th	Day	20% 16% 30% 21% 10% 2	455
	11th to 20th	Day	23% 24% 28% 17% 6% 1	285
	21st to end	Day	23% 24% 30% 20% 3 1	270
December	1st to 10th	Day	29% 27% 33% 9% 2	270
	11th to 20th	Day	27% 21% 35% 14% 3	270
	21st to end	Day	30% 26% 26% 13% 5%	297
January	1st to 10th	Night	24% 25% 33% 14% 3	760
	11th to 20th	Night	22% 23% 35% 18% 2	760
	21st to end	Night	20% 24% 38% 17% 1	836
February	1st to 10th	Night	19% 21% 36% 21% 2	760
	11th to 20th	Night	29% 26% 32% 13%	722
	21st to end	Night	24% 23% 35% 17% 2	592
March	1st to 10th	Night	20% 21% 37% 20% 2	720
	11th to 20th	Night	24% 20% 30% 18% 7% 1	720
	21st to end	Night	21% 18% 34% 21% 5%	792
April	1st to 10th	Night	19% 22% 30% 23% 6%	720
	11th to 20th	Night	20% 19% 26% 25% 10% 1	711
	21st to end	Night	18% 14% 31% 30% 7%	580
May	1st to 10th	Night	15% 13% 30% 26% 15% 1	540
	11th to 20th	Night	17% 9% 27% 29% 17% 2	531
	21st to end	Night	18% 4 15% 31% 27% 5%	584
June	1st to 10th	Night	11% 3 20% 35% 28% 3	540
	11th to 20th	Night	13% 4 17% 30% 31% 4	540
	21st to end	Night	7% 3 18% 37% 31% 4	540
July	1st to 10th	Night	11% 2 11% 32% 38% 5%	525
	11th to 20th	Night	6% 2 10% 33% 43% 6%	522
	21st to end	Night	8% 3 10% 36% 36% 7%	591
August	1st to 10th	Night	16% 2 12% 31% 35% 4	537
	11th to 20th	Night	14% 2 12% 33% 33% 6%	534
	21st to end	Night	11% 2 12% 30% 38% 7%	724
September	1st to 10th	Night	12% 4 13% 30% 33% 8%	720
	11th to 20th	Night	16% 5% 15% 31% 29% 5%	720
	21st to end	Night	21% 8% 19% 29% 20% 2	720
October	1st to 10th	Night	16% 11% 21% 22% 25% 4	720
	11th to 20th	Night	17% 10% 28% 28% 15% 2	720
	21st to end	Night	18% 12% 26% 31% 11% 2	792
November	1st to 10th	Night	18% 11% 30% 25% 14% 2	740
	11th to 20th	Night	19% 16% 28% 29% 8% 1	760
	21st to end	Night	19% 17% 29% 25% 9% 1	760
December	1st to 10th	Night	25% 21% 29% 21% 4	760
	11th to 20th	Night	20% 20% 33% 21% 6%	760
	21st to end	Night	28% 18% 28% 22% 4	836

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