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 2026-07-31.

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% 6% 2 6% 4 4 5% 4 6% 8% 40%	138279
	Night	15% 6% 2 5% 4 4 4 3 5% 7% 45%	134746
Transparency	Day	27% 38% 8% 13% 10% 3	141911
	Night	25% 37% 9% 14% 11% 4	139186
Seeing	Day	21% 16% 26% 20% 12% 5%	17570
	Night	19% 14% 26% 25% 15% 2	27628

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	16% 6% 2 4 3 3 3 3 5% 6% 49%	5258
	11th to 20th	Day	10% 7% 2 5% 4 3 3 2 4 4 57%	5280
	21st to end	Day	17% 8% 2 5% 3 4 3 2 4 5% 46%	5780
February	1st to 10th	Day	13% 8% 2 6% 5% 4 4 4 6% 6% 42%	1890
	11th to 20th	Day	19% 8% 2 5% 3 3 5% 3 5% 6% 40%	1958
	21st to end	Day	19% 7% 3 6% 3 3 5% 3 5% 6% 40%	1781
March	1st to 10th	Day	19% 7% 2 5% 4 4 4 4 5% 7% 39%	5045
	11th to 20th	Day	13% 5% 2 4 3 3 4 3 5% 7% 52%	5090
	21st to end	Day	18% 7% 2 5% 4 3 4 3 5% 6% 43%	5586
April	1st to 10th	Day	12% 5% 2 5% 3 4 5% 4 6% 8% 47%	2341
	11th to 20th	Day	15% 5% 2 5% 3 4 4 3 5% 8% 44%	2494
	21st to end	Day	15% 7% 2 6% 5% 5% 4 4 5% 7% 40%	2701
May	1st to 10th	Day	14% 6% 2 7% 5% 6% 6% 5% 7% 9% 34%	7616
	11th to 20th	Day	18% 6% 2 6% 4 5% 5% 4 6% 8% 36%	7626
	21st to end	Day	20% 6% 2 7% 5% 5% 5% 4 6% 8% 33%	8391
June	1st to 10th	Day	11% 6% 2 7% 5% 6% 6% 5% 7% 8% 37%	2730
	11th to 20th	Day	9% 6% 2 6% 6% 7% 7% 5% 8% 10% 36%	2730
	21st to end	Day	9% 5% 3 6% 6% 5% 6% 6% 8% 10% 37%	2730
July	1st to 10th	Day	8% 5% 2 7% 6% 5% 7% 6% 8% 10% 35%	6030
	11th to 20th	Day	9% 6% 3 8% 7% 7% 8% 7% 9% 11% 27%	6030
	21st to end	Day	12% 7% 3 9% 7% 7% 7% 5% 8% 9% 25%	6554
August	1st to 10th	Day	16% 7% 3 8% 6% 6% 6% 5% 7% 10% 26%	4234
	11th to 20th	Day	9% 5% 2 6% 5% 6% 7% 5% 8% 9% 36%	4174
	21st to end	Day	7% 4 2 5% 4 5% 5% 5% 6% 11% 48%	4390
September	1st to 10th	Day	12% 6% 2 5% 4 4 5% 4 6% 8% 43%	2289
	11th to 20th	Day	16% 5% 2 7% 5% 4 4 4 6% 7% 39%	2200
	21st to end	Day	23% 7% 2 6% 4 4 4 4 5% 6% 35%	2200
October	1st to 10th	Day	14% 6% 2 6% 3 3 4 3 4 7% 49%	2050
	11th to 20th	Day	15% 4 2 4 3 3 3 3 4 6% 53%	2000
	21st to end	Day	16% 5% 2 5% 3 3 2 2 4 5% 53%	2200
November	1st to 10th	Day	12% 5% 2 4 3 3 4 2 4 5% 54%	2057
	11th to 20th	Day	13% 5% 1 4 3 3 6% 2 4 7% 52%	1906
	21st to end	Day	14% 6% 2 5% 4 3 3 3 5% 7% 49%	1890
December	1st to 10th	Day	15% 9% 2 6% 3 3 3 3 4 5% 48%	3020
	11th to 20th	Day	18% 8% 2 4 3 4 3 3 5% 6% 45%	3463
	21st to end	Day	24% 7% 1 5% 3 4 4 3 6% 8% 36%	4565
January	1st to 10th	Night	14% 6% 2 4 3 3 3 3 4 5% 54%	7635
	11th to 20th	Night	11% 6% 2 5% 3 4 3 2 4 4 56%	7680
	21st to end	Night	17% 7% 2 4 3 2 3 2 4 6% 49%	8401
February	1st to 10th	Night	14% 7% 2 5% 4 4 4 3 6% 7% 44%	2730
	11th to 20th	Night	20% 6% 2 6% 4 3 3 3 4 6% 42%	2544
	21st to end	Night	16% 7% 2 5% 4 4 4 4 6% 6% 41%	2024
March	1st to 10th	Night	19% 7% 2 5% 4 3 4 3 4 5% 43%	5028
	11th to 20th	Night	11% 3 1 3 3 3 3 3 5% 8% 56%	5090
	21st to end	Night	15% 5% 2 5% 4 5% 5% 4 6% 7% 44%	5588
April	1st to 10th	Night	14% 5% 2 5% 4 4 3 3 6% 8% 45%	2279
	11th to 20th	Night	15% 5% 2 5% 3 4 4 3 5% 8% 47%	2075
	21st to end	Night	15% 5% 1 4 4 4 4 4 6% 6% 48%	1936
May	1st to 10th	Night	15% 6% 2 6% 4 3 4 4 7% 10% 40%	5237
	11th to 20th	Night	17% 5% 2 6% 4 4 4 3 5% 8% 42%	5234
	21st to end	Night	25% 5% 2 5% 3 4 4 3 6% 8% 33%	5761
June	1st to 10th	Night	11% 5% 2 6% 5% 4 5% 4 6% 10% 42%	1890
	11th to 20th	Night	12% 6% 2 5% 4 3 4 3 7% 10% 43%	1890
	21st to end	Night	8% 5% 2 4 5% 5% 5% 5% 7% 11% 44%	1890
July	1st to 10th	Night	12% 6% 2 7% 5% 5% 5% 4 7% 9% 39%	4148
	11th to 20th	Night	10% 5% 2 6% 5% 5% 6% 6% 8% 12% 34%	4147
	21st to end	Night	11% 7% 3 8% 6% 6% 6% 5% 8% 10% 30%	4517
August	1st to 10th	Night	18% 9% 3 7% 4 5% 6% 4 7% 10% 29%	2915
	11th to 20th	Night	11% 5% 2 6% 4 4 5% 4 8% 11% 39%	2875
	21st to end	Night	7% 3 1 5% 4 4 4 4 6% 9% 52%	3472
September	1st to 10th	Night	11% 5% 2 5% 4 4 5% 4 6% 7% 47%	2107
	11th to 20th	Night	16% 6% 2 7% 5% 4 4 3 5% 7% 41%	2200
	21st to end	Night	20% 7% 3 6% 4 4 5% 3 6% 6% 36%	2200
October	1st to 10th	Night	15% 5% 2 5% 3 3 4 3 4 6% 48%	2348
	11th to 20th	Night	14% 5% 2 4 3 3 4 3 4 6% 53%	2400
	21st to end	Night	15% 4 2 4 3 2 3 3 4 5% 56%	2640
November	1st to 10th	Night	15% 5% 2 5% 3 3 3 2 4 5% 53%	2461
	11th to 20th	Night	14% 4 1 4 3 3 3 3 4 6% 54%	2709
	21st to end	Night	14% 4 1 4 4 3 3 4 6% 7% 49%	2730
December	1st to 10th	Night	13% 8% 2 6% 3 3 3 2 4 5% 50%	4380
	11th to 20th	Night	20% 10% 2 6% 3 3 3 3 4 6% 40%	4952
	21st to end	Night	22% 5% 1 4 3 3 4 4 5% 7% 42%	6633

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	29% 23% 10% 12% 22% 4	5259
	11th to 20th	Day	23% 22% 4 12% 29% 10%	5280
	21st to end	Day	33% 23% 5% 17% 16% 5%	5780
February	1st to 10th	Day	18% 60% 4 8% 8% 2	1890
	11th to 20th	Day	21% 58% 2 8% 8% 2	1967
	21st to end	Day	20% 60% 3 7% 8% 2	1781
March	1st to 10th	Day	36% 31% 6% 10% 8% 10%	5045
	11th to 20th	Day	20% 30% 4 17% 18% 11%	5090
	21st to end	Day	29% 30% 6% 17% 14% 4	5586
April	1st to 10th	Day	17% 61% 5% 10% 6% 1	2341
	11th to 20th	Day	17% 61% 6% 10% 6% 1	2494
	21st to end	Day	17% 60% 5% 12% 5% 1	2701
May	1st to 10th	Day	34% 28% 10% 17% 10% 1	7651
	11th to 20th	Day	35% 26% 11% 20% 8%	7630
	21st to end	Day	40% 27% 9% 11% 11% 3	8405
June	1st to 10th	Day	17% 61% 6% 9% 6%	2730
	11th to 20th	Day	16% 63% 7% 9% 5%	2730
	21st to end	Day	18% 61% 8% 10% 3	2730
July	1st to 10th	Day	31% 32% 12% 15% 7% 2	5965
	11th to 20th	Day	36% 34% 15% 13% 2	5961
	21st to end	Day	40% 31% 11% 13% 4	6370
August	1st to 10th	Day	35% 40% 11% 12% 1	4221
	11th to 20th	Day	22% 42% 15% 14% 5% 2	4213
	21st to end	Day	15% 40% 13% 23% 8% 1	4390
September	1st to 10th	Day	15% 60% 7% 9% 8% 2	2289
	11th to 20th	Day	19% 60% 6% 9% 6% 1	2200
	21st to end	Day	25% 59% 6% 7% 2	2200
October	1st to 10th	Day	16% 38% 6% 12% 20% 8%	3336
	11th to 20th	Day	12% 36% 5% 14% 17% 17%	3240
	21st to end	Day	15% 36% 7% 17% 12% 12%	3538
November	1st to 10th	Day	19% 54% 5% 11% 9% 3	2057
	11th to 20th	Day	17% 55% 4 8% 13% 3	1906
	21st to end	Day	17% 55% 5% 10% 12% 1	1890
December	1st to 10th	Day	25% 35% 5% 13% 19% 4	3020
	11th to 20th	Day	29% 32% 8% 11% 16% 4	3460
	21st to end	Day	35% 29% 10% 16% 9% 2	4565
January	1st to 10th	Night	26% 22% 12% 15% 17% 7%	7636
	11th to 20th	Night	24% 22% 7% 14% 25% 9%	7680
	21st to end	Night	30% 23% 6% 18% 19% 4	8401
February	1st to 10th	Night	17% 60% 6% 8% 8% 1	2730
	11th to 20th	Night	21% 58% 4 8% 8% 1	2546
	21st to end	Night	18% 59% 5% 9% 6% 3	2024
March	1st to 10th	Night	33% 30% 6% 14% 10% 7%	5028
	11th to 20th	Night	16% 29% 5% 17% 20% 13%	5090
	21st to end	Night	28% 31% 9% 17% 13% 3	5588
April	1st to 10th	Night	17% 61% 6% 9% 7% 1	2279
	11th to 20th	Night	16% 60% 5% 11% 5% 2	2075
	21st to end	Night	14% 60% 5% 13% 7%	1936
May	1st to 10th	Night	31% 29% 11% 17% 10% 1	5264
	11th to 20th	Night	32% 26% 12% 20% 9%	5235
	21st to end	Night	40% 27% 11% 15% 6% 1	5771
June	1st to 10th	Night	15% 62% 7% 10% 6% 1	1890
	11th to 20th	Night	13% 63% 9% 12% 4	1890
	21st to end	Night	14% 60% 8% 12% 5%	1890
July	1st to 10th	Night	31% 32% 12% 17% 7%	4105
	11th to 20th	Night	32% 33% 20% 13% 2	4096
	21st to end	Night	37% 31% 13% 13% 5%	4387
August	1st to 10th	Night	35% 39% 13% 10% 2	2904
	11th to 20th	Night	20% 41% 15% 18% 5%	2902
	21st to end	Night	14% 38% 10% 30% 6% 1	3472
September	1st to 10th	Night	16% 59% 8% 9% 7% 1	2107
	11th to 20th	Night	18% 60% 6% 8% 7%	2200
	21st to end	Night	24% 60% 6% 8% 2	2200
October	1st to 10th	Night	21% 37% 5% 13% 17% 7%	3842
	11th to 20th	Night	12% 37% 6% 13% 17% 16%	3899
	21st to end	Night	13% 36% 4 19% 14% 14%	4252
November	1st to 10th	Night	20% 53% 5% 11% 9% 2	2461
	11th to 20th	Night	14% 54% 4 10% 12% 5%	2709
	21st to end	Night	15% 55% 5% 11% 12% 2	2730
December	1st to 10th	Night	23% 36% 6% 16% 18% 1	4380
	11th to 20th	Night	33% 32% 7% 11% 12% 5%	4954
	21st to end	Night	31% 28% 12% 17% 11% 2	6633

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% 25% 7% 2	330
	11th to 20th	Day	38% 31% 26% 4 1	330
	21st to end	Day	33% 34% 26% 5% 1	363
February	1st to 10th	Day	28% 34% 28% 10% 2	330
	11th to 20th	Day	48% 25% 22% 3 1	330
	21st to end	Day	33% 30% 29% 6% 2	324
March	1st to 10th	Day	27% 26% 30% 13% 3 1	540
	11th to 20th	Day	29% 29% 28% 11% 3 1	540
	21st to end	Day	30% 23% 31% 13% 3	594
April	1st to 10th	Day	25% 27% 27% 14% 7% 1	540
	11th to 20th	Day	25% 21% 27% 18% 8% 2	532
	21st to end	Day	21% 19% 30% 18% 9% 2	540
May	1st to 10th	Day	22% 21% 33% 15% 8% 2	543
	11th to 20th	Day	21% 15% 28% 21% 10% 5%	567
	21st to end	Day	22% 11% 22% 24% 16% 6%	617
June	1st to 10th	Day	12% 10% 31% 28% 12% 6%	570
	11th to 20th	Day	9% 12% 26% 30% 16% 6%	570
	21st to end	Day	10% 7% 27% 38% 13% 5%	570
July	1st to 10th	Day	10% 3 18% 34% 24% 11%	565
	11th to 20th	Day	7% 6% 19% 30% 29% 9%	564
	21st to end	Day	14% 7% 20% 27% 21% 11%	616
August	1st to 10th	Day	18% 6% 22% 23% 17% 13%	526
	11th to 20th	Day	11% 5% 24% 26% 20% 14%	519
	21st to end	Day	11% 4 20% 29% 21% 15%	583
September	1st to 10th	Day	12% 5% 20% 28% 25% 10%	530
	11th to 20th	Day	15% 7% 16% 28% 23% 10%	530
	21st to end	Day	22% 13% 23% 25% 13% 3	530
October	1st to 10th	Day	16% 11% 24% 26% 19% 4	530
	11th to 20th	Day	15% 19% 27% 22% 15% 1	530
	21st to end	Day	23% 15% 29% 23% 8% 2	583
November	1st to 10th	Day	21% 17% 32% 20% 9% 2	535
	11th to 20th	Day	24% 27% 28% 15% 5% 1	346
	21st to end	Day	28% 23% 28% 18% 2 1	330
December	1st to 10th	Day	32% 28% 31% 7% 2	330
	11th to 20th	Day	29% 20% 36% 13% 3	330
	21st to end	Day	33% 25% 26% 12% 4	363
January	1st to 10th	Night	27% 24% 32% 14% 3	840
	11th to 20th	Night	25% 23% 35% 16% 2	840
	21st to end	Night	22% 25% 37% 16% 1	924
February	1st to 10th	Night	20% 22% 36% 20% 2	840
	11th to 20th	Night	30% 26% 31% 12%	823
	21st to end	Night	25% 22% 35% 16% 1	692
March	1st to 10th	Night	21% 20% 36% 20% 3	840
	11th to 20th	Night	25% 20% 30% 18% 6% 1	840
	21st to end	Night	21% 19% 35% 20% 4	924
April	1st to 10th	Night	21% 21% 30% 23% 5%	840
	11th to 20th	Night	19% 19% 27% 26% 9% 1	831
	21st to end	Night	17% 14% 31% 31% 7%	676
May	1st to 10th	Night	15% 14% 31% 25% 14% 1	630
	11th to 20th	Night	17% 9% 26% 30% 16% 1	621
	21st to end	Night	20% 6% 17% 29% 24% 4	683
June	1st to 10th	Night	11% 4 22% 35% 26% 3	630
	11th to 20th	Night	13% 5% 18% 31% 30% 4	630
	21st to end	Night	7% 3 17% 37% 32% 4	630
July	1st to 10th	Night	10% 4 11% 32% 39% 5%	615
	11th to 20th	Night	6% 3 11% 33% 42% 6%	612
	21st to end	Night	10% 4 11% 34% 34% 6%	687
August	1st to 10th	Night	16% 3 13% 30% 34% 3	597
	11th to 20th	Night	15% 3 13% 32% 32% 5%	594
	21st to end	Night	12% 3 12% 30% 37% 7%	805
September	1st to 10th	Night	12% 5% 14% 31% 31% 8%	800
	11th to 20th	Night	16% 5% 15% 30% 29% 5%	800
	21st to end	Night	23% 9% 19% 29% 19% 2	800
October	1st to 10th	Night	16% 10% 22% 23% 25% 4	800
	11th to 20th	Night	18% 12% 27% 28% 15% 2	800
	21st to end	Night	19% 13% 25% 31% 11% 1	880
November	1st to 10th	Night	19% 12% 30% 25% 13% 2	820
	11th to 20th	Night	20% 17% 28% 28% 7% 1	840
	21st to end	Night	21% 18% 29% 23% 8% 1	840
December	1st to 10th	Night	25% 21% 30% 20% 4	840
	11th to 20th	Night	22% 20% 33% 21% 5%	840
	21st to end	Night	28% 19% 27% 22% 4	924

Page generated at 2026-07-28 03:25:22. Version ac07

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