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 2025-03-27.

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 6% 4 4 5% 4 6% 8% 41%	109567
	Night	15% 6% 2 5% 4 4 4 3 5% 7% 45%	109785
Transparency	Day	23% 45% 7% 12% 9% 3	113243
	Night	21% 43% 7% 13% 11% 4	114248
Seeing	Day	21% 16% 26% 21% 12% 5%	15713
	Night	19% 14% 26% 25% 15% 2	25890

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	14% 6% 2 4 3 2 3 3 4 6% 52%	4056
	11th to 20th	Day	12% 6% 2 5% 4 3 3 3 4 4 54%	4060
	21st to end	Day	18% 6% 2 5% 4 4 3 2 4 5% 45%	4466
February	1st to 10th	Day	13% 8% 2 6% 5% 4 4 5% 6% 6% 41%	1800
	11th to 20th	Day	19% 8% 2 5% 3 3 5% 3 5% 6% 40%	1862
	21st to end	Day	20% 6% 3 6% 4 3 4 3 4 6% 40%	1699
March	1st to 10th	Day	23% 7% 2 4 3 3 4 4 5% 7% 38%	3545
	11th to 20th	Day	12% 5% 2 4 4 3 4 3 5% 7% 52%	3590
	21st to end	Day	20% 8% 2 5% 4 3 4 4 5% 6% 40%	3881
April	1st to 10th	Day	12% 5% 2 5% 3 3 5% 4 5% 8% 47%	2118
	11th to 20th	Day	16% 5% 2 6% 4 4 4 3 5% 8% 43%	2254
	21st to end	Day	15% 7% 2 6% 5% 5% 5% 4 5% 7% 40%	2443
May	1st to 10th	Day	16% 6% 3 7% 5% 6% 6% 5% 7% 8% 31%	4082
	11th to 20th	Day	20% 7% 3 7% 5% 4 5% 4 6% 8% 31%	4081
	21st to end	Day	10% 4 2 6% 4 5% 5% 4 8% 9% 41%	4476
June	1st to 10th	Day	11% 6% 2 6% 5% 6% 6% 4 7% 8% 36%	2470
	11th to 20th	Day	9% 6% 2 6% 6% 6% 7% 5% 7% 10% 36%	2470
	21st to end	Day	9% 5% 3 6% 6% 5% 6% 6% 8% 10% 36%	2470
July	1st to 10th	Day	8% 4 2 7% 6% 6% 7% 6% 10% 10% 33%	4120
	11th to 20th	Day	9% 5% 3 7% 6% 7% 6% 6% 8% 10% 32%	4120
	21st to end	Day	15% 8% 3 10% 7% 7% 7% 5% 7% 7% 23%	4466
August	1st to 10th	Day	15% 7% 3 8% 6% 6% 6% 5% 7% 11% 27%	4104
	11th to 20th	Day	9% 5% 2 6% 6% 5% 7% 5% 8% 9% 37%	4044
	21st to end	Day	6% 4 1 5% 4 5% 5% 5% 6% 11% 48%	4256
September	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 6% 8% 43%	2175
	11th to 20th	Day	17% 6% 2 8% 4 4 4 4 6% 7% 38%	2090
	21st to end	Day	23% 6% 3 6% 4 4 4 4 5% 5% 36%	2090
October	1st to 10th	Day	14% 6% 2 6% 3 3 4 3 4 7% 49%	1948
	11th to 20th	Day	15% 4 2 4 3 3 3 3 4 6% 52%	1900
	21st to end	Day	15% 5% 2 6% 3 3 2 2 3 5% 53%	2090
November	1st to 10th	Day	13% 5% 2 4 3 3 4 2 4 5% 53%	1957
	11th to 20th	Day	14% 5% 1 4 3 3 5% 2 4 7% 51%	1815
	21st to end	Day	14% 6% 2 5% 4 3 3 3 5% 7% 49%	1800
December	1st to 10th	Day	15% 9% 2 5% 3 2 3 3 4 5% 49%	2930
	11th to 20th	Day	18% 8% 2 4 3 3 4 3 5% 6% 44%	3373
	21st to end	Day	24% 7% 2 5% 3 4 4 3 6% 8% 36%	4466
January	1st to 10th	Night	13% 6% 2 4 3 2 3 3 4 6% 55%	5889
	11th to 20th	Night	12% 6% 2 5% 3 4 3 3 4 5% 53%	5900
	21st to end	Night	18% 6% 2 4 3 2 3 2 4 5% 50%	6490
February	1st to 10th	Night	14% 7% 2 5% 4 4 4 3 6% 7% 44%	2600
	11th to 20th	Night	20% 6% 2 5% 4 4 3 3 4 6% 42%	2420
	21st to end	Night	16% 7% 2 5% 4 4 5% 4 6% 6% 42%	1930
March	1st to 10th	Night	23% 9% 2 6% 4 3 4 3 5% 5% 36%	3528
	11th to 20th	Night	11% 3 1 4 3 4 3 3 5% 7% 55%	3590
	21st to end	Night	17% 6% 2 4 3 4 4 3 6% 6% 45%	3890
April	1st to 10th	Night	14% 6% 2 5% 4 4 3 3 5% 8% 45%	2062
	11th to 20th	Night	16% 5% 2 5% 3 4 4 3 5% 8% 47%	1875
	21st to end	Night	15% 5% 1 4 3 4 3 4 5% 6% 48%	1752
May	1st to 10th	Night	17% 8% 2 6% 4 3 4 3 5% 8% 39%	2813
	11th to 20th	Night	19% 7% 2 7% 3 4 3 4 5% 7% 38%	2812
	21st to end	Night	12% 4 2 5% 4 4 4 4 7% 10% 45%	3079
June	1st to 10th	Night	11% 5% 2 5% 5% 4 5% 5% 7% 10% 42%	1710
	11th to 20th	Night	12% 6% 2 5% 4 3 4 3 7% 10% 44%	1710
	21st to end	Night	8% 5% 1 4 5% 5% 5% 5% 7% 10% 44%	1710
July	1st to 10th	Night	10% 5% 2 6% 5% 5% 5% 5% 8% 9% 40%	2840
	11th to 20th	Night	9% 5% 2 5% 4 4 5% 5% 8% 12% 41%	2840
	21st to end	Night	13% 9% 4 8% 6% 6% 6% 5% 7% 9% 28%	3087
August	1st to 10th	Night	17% 8% 3 7% 4 4 6% 4 7% 10% 29%	2825
	11th to 20th	Night	11% 5% 2 6% 4 4 5% 4 8% 11% 40%	2785
	21st to end	Night	7% 3 1 5% 4 4 4 4 6% 9% 53%	3366
September	1st to 10th	Night	11% 5% 2 5% 4 4 5% 4 6% 7% 47%	2001
	11th to 20th	Night	16% 7% 2 7% 5% 4 4 3 4 8% 40%	2090
	21st to end	Night	20% 7% 3 6% 4 4 4 3 5% 6% 37%	2090
October	1st to 10th	Night	15% 5% 2 5% 3 3 4 3 4 5% 48%	2230
	11th to 20th	Night	14% 5% 1 4 3 3 3 3 4 6% 52%	2280
	21st to end	Night	14% 4 2 4 3 2 3 3 4 5% 56%	2508
November	1st to 10th	Night	16% 5% 2 5% 3 3 3 3 4 5% 52%	2341
	11th to 20th	Night	15% 4 1 4 3 3 3 3 4 6% 53%	2580
	21st to end	Night	14% 4 1 4 4 3 3 4 6% 7% 49%	2600
December	1st to 10th	Night	13% 8% 2 5% 3 3 3 2 5% 5% 51%	4250
	11th to 20th	Night	20% 10% 2 6% 3 3 3 3 4 6% 40%	4822
	21st to end	Night	22% 5% 1 3 3 3 4 4 5% 7% 42%	6490

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	25% 28% 6% 13% 24% 5%	4057
	11th to 20th	Day	22% 28% 5% 12% 28% 6%	4060
	21st to end	Day	30% 30% 5% 14% 17% 4	4466
February	1st to 10th	Day	17% 63% 4 7% 7% 2	1800
	11th to 20th	Day	20% 61% 2 7% 8% 2	1871
	21st to end	Day	18% 62% 3 6% 7% 3	1699
March	1st to 10th	Day	32% 42% 6% 9% 5% 6%	3545
	11th to 20th	Day	15% 41% 4 18% 13% 8%	3590
	21st to end	Day	25% 41% 5% 15% 11% 3	3881
April	1st to 10th	Day	14% 67% 3 8% 6% 1	2118
	11th to 20th	Day	16% 66% 4 8% 4 1	2254
	21st to end	Day	15% 66% 4 9% 5% 1	2443
May	1st to 10th	Day	29% 46% 8% 12% 4 1	4120
	11th to 20th	Day	30% 43% 6% 15% 4	4085
	21st to end	Day	18% 45% 11% 12% 11% 3	4489
June	1st to 10th	Day	15% 67% 5% 8% 4	2470
	11th to 20th	Day	13% 69% 6% 7% 5%	2470
	21st to end	Day	17% 66% 6% 8% 3 1	2470
July	1st to 10th	Day	26% 44% 12% 11% 4 3	4055
	11th to 20th	Day	28% 41% 13% 15% 2	4051
	21st to end	Day	41% 40% 6% 11% 2	4324
August	1st to 10th	Day	34% 41% 11% 12% 1	4091
	11th to 20th	Day	21% 43% 15% 14% 5% 2	4083
	21st to end	Day	14% 41% 13% 23% 8% 1	4256
September	1st to 10th	Day	14% 63% 7% 8% 6% 2	2175
	11th to 20th	Day	18% 62% 5% 7% 6% 1	2090
	21st to end	Day	23% 61% 6% 7% 3	2090
October	1st to 10th	Day	16% 39% 6% 11% 20% 8%	3234
	11th to 20th	Day	11% 37% 5% 13% 16% 17%	3140
	21st to end	Day	14% 37% 6% 17% 12% 13%	3428
November	1st to 10th	Day	19% 56% 4 10% 8% 3	1957
	11th to 20th	Day	16% 57% 4 6% 13% 4	1815
	21st to end	Day	16% 58% 5% 9% 12% 1	1800
December	1st to 10th	Day	24% 36% 4 12% 19% 4	2930
	11th to 20th	Day	29% 32% 8% 11% 16% 4	3370
	21st to end	Day	35% 29% 9% 15% 9% 2	4466
January	1st to 10th	Night	23% 27% 7% 14% 21% 9%	5889
	11th to 20th	Night	22% 27% 8% 12% 23% 8%	5900
	21st to end	Night	27% 29% 4 15% 21% 3	6490
February	1st to 10th	Night	16% 63% 5% 7% 7% 1	2600
	11th to 20th	Night	20% 61% 4 7% 7% 1	2422
	21st to end	Night	16% 62% 4 9% 6% 3	1930
March	1st to 10th	Night	36% 42% 5% 9% 6% 2	3528
	11th to 20th	Night	13% 40% 5% 16% 14% 12%	3590
	21st to end	Night	22% 41% 6% 15% 12% 4	3890
April	1st to 10th	Night	15% 66% 4 8% 6% 1	2062
	11th to 20th	Night	15% 66% 4 8% 5% 1	1875
	21st to end	Night	12% 66% 5% 11% 6%	1752
May	1st to 10th	Night	28% 44% 9% 15% 4	2840
	11th to 20th	Night	29% 42% 7% 18% 5%	2813
	21st to end	Night	15% 45% 12% 18% 7% 3	3087
June	1st to 10th	Night	13% 68% 6% 8% 4 1	1710
	11th to 20th	Night	10% 68% 8% 10% 4 1	1710
	21st to end	Night	12% 66% 7% 10% 5%	1710
July	1st to 10th	Night	26% 43% 12% 13% 6%	2795
	11th to 20th	Night	20% 41% 20% 17% 2 1	2786
	21st to end	Night	38% 39% 8% 11% 3	2988
August	1st to 10th	Night	34% 40% 14% 10% 2	2814
	11th to 20th	Night	20% 41% 15% 18% 5%	2812
	21st to end	Night	14% 39% 10% 30% 6% 1	3366
September	1st to 10th	Night	15% 62% 7% 9% 6% 2	2001
	11th to 20th	Night	18% 63% 5% 7% 7%	2090
	21st to end	Night	23% 62% 5% 8% 3	2090
October	1st to 10th	Night	21% 38% 5% 12% 16% 7%	3724
	11th to 20th	Night	11% 38% 6% 12% 17% 16%	3779
	21st to end	Night	12% 37% 4 19% 13% 14%	4120
November	1st to 10th	Night	20% 56% 5% 9% 9% 2	2341
	11th to 20th	Night	14% 57% 4 9% 12% 5%	2580
	21st to end	Night	14% 58% 5% 10% 12% 1	2600
December	1st to 10th	Night	22% 37% 6% 16% 18% 1	4250
	11th to 20th	Night	33% 33% 7% 11% 11% 5%	4824
	21st to end	Night	31% 28% 12% 17% 11% 1	6490

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	37% 29% 24% 8% 2	300
	11th to 20th	Day	36% 32% 26% 5% 1	300
	21st to end	Day	32% 33% 28% 5% 2	330
February	1st to 10th	Day	27% 35% 27% 10% 2	300
	11th to 20th	Day	47% 26% 22% 3 1	300
	21st to end	Day	33% 30% 29% 6% 2	298
March	1st to 10th	Day	28% 27% 29% 13% 3 1	500
	11th to 20th	Day	28% 29% 28% 11% 3 1	500
	21st to end	Day	30% 23% 29% 14% 3	530
April	1st to 10th	Day	24% 28% 27% 14% 7% 1	460
	11th to 20th	Day	24% 20% 26% 20% 9% 2	452
	21st to end	Day	22% 19% 30% 17% 10% 2	460
May	1st to 10th	Day	20% 19% 34% 15% 9% 3	463
	11th to 20th	Day	20% 13% 28% 22% 11% 5%	487
	21st to end	Day	19% 8% 23% 26% 18% 6%	529
June	1st to 10th	Day	13% 9% 29% 29% 13% 6%	490
	11th to 20th	Day	10% 10% 24% 31% 18% 7%	490
	21st to end	Day	11% 7% 28% 37% 12% 6%	490
July	1st to 10th	Day	11% 3 18% 34% 22% 12%	485
	11th to 20th	Day	7% 5% 19% 31% 28% 10%	484
	21st to end	Day	12% 6% 20% 28% 22% 11%	532
August	1st to 10th	Day	17% 6% 23% 23% 18% 14%	486
	11th to 20th	Day	11% 5% 25% 26% 19% 14%	479
	21st to end	Day	11% 3 17% 30% 23% 16%	539
September	1st to 10th	Day	12% 5% 19% 28% 26% 11%	490
	11th to 20th	Day	16% 7% 16% 28% 23% 10%	490
	21st to end	Day	22% 13% 22% 24% 14% 3	490
October	1st to 10th	Day	17% 10% 25% 25% 19% 4	490
	11th to 20th	Day	15% 19% 26% 22% 17% 1	490
	21st to end	Day	21% 14% 30% 24% 8% 2	539
November	1st to 10th	Day	21% 16% 31% 21% 9% 2	495
	11th to 20th	Day	23% 25% 29% 17% 6% 1	315
	21st to end	Day	26% 23% 29% 18% 3 1	300
December	1st to 10th	Day	32% 27% 31% 8% 2	300
	11th to 20th	Day	28% 19% 36% 14% 3	300
	21st to end	Day	32% 24% 26% 14% 4	330
January	1st to 10th	Night	27% 25% 31% 14% 3	800
	11th to 20th	Night	24% 23% 35% 17% 2	800
	21st to end	Night	20% 25% 38% 16% 1	880
February	1st to 10th	Night	20% 22% 36% 21% 2	800
	11th to 20th	Night	30% 27% 31% 12%	783
	21st to end	Night	24% 22% 35% 17% 2	660
March	1st to 10th	Night	22% 21% 35% 20% 3	800
	11th to 20th	Night	25% 20% 30% 18% 6% 1	800
	21st to end	Night	22% 19% 34% 20% 4	863
April	1st to 10th	Night	19% 22% 31% 23% 5%	760
	11th to 20th	Night	20% 19% 26% 25% 9% 1	751
	21st to end	Night	17% 15% 31% 30% 7%	612
May	1st to 10th	Night	15% 13% 30% 26% 15% 1	570
	11th to 20th	Night	17% 9% 27% 29% 17% 2	561
	21st to end	Night	17% 5% 16% 31% 27% 4	617
June	1st to 10th	Night	11% 4 21% 36% 27% 3	570
	11th to 20th	Night	13% 4 17% 31% 31% 4	570
	21st to end	Night	8% 3 17% 36% 32% 4	570
July	1st to 10th	Night	11% 3 11% 32% 38% 5%	555
	11th to 20th	Night	6% 2 10% 33% 43% 6%	552
	21st to end	Night	9% 3 11% 36% 34% 7%	624
August	1st to 10th	Night	16% 3 13% 31% 34% 4	567
	11th to 20th	Night	14% 2 13% 33% 32% 6%	564
	21st to end	Night	11% 2 12% 30% 38% 8%	765
September	1st to 10th	Night	12% 5% 14% 30% 32% 8%	760
	11th to 20th	Night	16% 5% 16% 30% 29% 5%	760
	21st to end	Night	22% 9% 19% 29% 19% 2	760
October	1st to 10th	Night	16% 10% 22% 23% 24% 4	760
	11th to 20th	Night	18% 11% 27% 28% 15% 2	760
	21st to end	Night	17% 12% 25% 32% 12% 1	836
November	1st to 10th	Night	18% 11% 31% 25% 13% 2	780
	11th to 20th	Night	19% 16% 28% 29% 7% 1	800
	21st to end	Night	20% 18% 28% 24% 9% 1	800
December	1st to 10th	Night	25% 21% 29% 21% 4	800
	11th to 20th	Night	21% 20% 34% 21% 6%	800
	21st to end	Night	28% 18% 27% 22% 4	880

Page generated at 2025-03-24 09:04:31. Version ac07

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