Persimmon Gap
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Persimmon Gap clear sky chart from 2005-11-06 to 2024-02-25.

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	4 3 1 3 3 2 4 4 5% 7% 63%	79094
	Night	4 3 1 3 3 2 3 4 5% 8% 62%	80263
Transparency	Day	20% 5% 9% 19% 26% 22%	78844
	Night	21% 5% 9% 19% 24% 22%	80035
Seeing	Day	5% 6% 19% 32% 28% 10%	13565
	Night	6% 3 19% 46% 25% 1	23822

By Month

Percentage Cloud Cover SW (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	4 3 1 3 3 1 2 3 4 5% 72%	3167
	11th to 20th	Day	4 2 1 2 2 1 2 2 4 6% 73%	3170
	21st to end	Day	3 4 2 4 4 3 3 3 4 6% 64%	3487
February	1st to 10th	Day	3 3 2 4 3 2 3 4 4 7% 65%	1900
	11th to 20th	Day	4 4 2 3 4 2 3 4 4 6% 64%	1849
	21st to end	Day	3 3 1 2 2 2 3 4 5% 8% 68%	1520
March	1st to 10th	Day	2 4 2 4 4 3 4 4 5% 8% 60%	1800
	11th to 20th	Day	7% 4 1 4 4 3 5% 4 4 5% 59%	1853
	21st to end	Day	3 3 1 2 3 1 3 3 4 7% 70%	2376
April	1st to 10th	Day	3 3 2 2 3 2 4 4 6% 7% 65%	2160
	11th to 20th	Day	2 3 1 3 2 1 3 3 4 6% 72%	2131
	21st to end	Day	4 4 1 3 2 2 3 4 4 6% 68%	2160
May	1st to 10th	Day	3 2 1 2 3 2 2 3 6% 7% 67%	2160
	11th to 20th	Day	4 3 1 3 3 2 4 4 5% 7% 64%	2133
	21st to end	Day	4 2 1 2 3 1 3 4 5% 8% 66%	2531
June	1st to 10th	Day	1 1 1 2 3 2 3 3 5% 9% 70%	2340
	11th to 20th	Day	2 1 1 2 4 2 4 4 5% 8% 66%	2340
	21st to end	Day	4 3 2 3 3 2 4 4 6% 9% 60%	2340
July	1st to 10th	Day	5% 3 2 4 5% 3 6% 6% 7% 10% 48%	2209
	11th to 20th	Day	3 2 1 2 3 2 4 4 6% 9% 63%	2160
	21st to end	Day	3 3 1 2 3 3 5% 6% 8% 11% 55%	2349
August	1st to 10th	Day	2 2 1 2 2 2 3 5% 7% 11% 62%	2149
	11th to 20th	Day	6% 3 2 3 5% 3 5% 7% 7% 10% 49%	2123
	21st to end	Day	4 3 1 3 4 3 5% 6% 8% 10% 52%	2376
September	1st to 10th	Day	7% 5% 2 5% 5% 3 5% 5% 6% 10% 49%	2160
	11th to 20th	Day	8% 4 2 4 4 3 5% 5% 6% 8% 51%	2006
	21st to end	Day	7% 3 1 3 5% 3 4 5% 5% 6% 59%	1980
October	1st to 10th	Day	3 3 1 2 2 3 3 3 5% 8% 66%	1980
	11th to 20th	Day	8% 4 1 3 3 2 3 3 4 5% 63%	1959
	21st to end	Day	6% 2 1 2 3 2 2 2 3 5% 71%	1980
November	1st to 10th	Day	7% 3 1 1 2 2 2 2 2 4 73%	1756
	11th to 20th	Day	5% 3 1 2 2 2 3 2 4 6% 69%	1710
	21st to end	Day	6% 4 1 3 4 2 3 3 4 5% 65%	1710
December	1st to 10th	Day	7% 5% 2 3 4 1 3 3 4 4 64%	1710
	11th to 20th	Day	3 4 1 4 4 3 4 5% 6% 7% 60%	2161
	21st to end	Day	3 3 1 2 3 2 3 4 5% 7% 67%	3199
January	1st to 10th	Night	3 2 1 2 2 2 2 2 3 5% 75%	3788
	11th to 20th	Night	4 2 2 3 2 1 2 2 3 5% 74%	3800
	21st to end	Night	6% 4 2 4 4 2 3 4 5% 7% 58%	4180
February	1st to 10th	Night	4 4 2 3 3 2 3 4 4 7% 64%	2280
	11th to 20th	Night	5% 3 2 4 4 2 4 4 5% 7% 59%	2218
	21st to end	Night	4 5% 2 3 3 2 3 4 4 5% 64%	1830
March	1st to 10th	Night	4 4 2 3 5% 3 3 4 5% 9% 58%	2160
	11th to 20th	Night	6% 5% 2 3 3 3 4 4 6% 6% 59%	2101
	21st to end	Night	4 4 1 2 3 2 3 3 4 6% 68%	1980
April	1st to 10th	Night	4 3 1 3 3 2 4 4 6% 6% 63%	1800
	11th to 20th	Night	4 2 1 3 3 2 3 4 5% 6% 67%	1777
	21st to end	Night	3 2 2 2 3 2 3 3 4 7% 70%	1800
May	1st to 10th	Night	4 2 1 2 4 3 3 5% 6% 8% 63%	1800
	11th to 20th	Night	6% 4 2 3 4 3 4 4 5% 6% 59%	1757
	21st to end	Night	4 3 1 3 3 3 6% 5% 7% 8% 57%	1745
June	1st to 10th	Night	2 1 1 2 3 2 3 5% 8% 12% 61%	1620
	11th to 20th	Night	2 1 1 3 3 4 4 6% 6% 11% 58%	1620
	21st to end	Night	3 2 1 2 3 2 4 4 8% 11% 61%	1620
July	1st to 10th	Night	5% 3 2 3 4 3 5% 6% 8% 13% 49%	1744
	11th to 20th	Night	2 1 1 2 2 2 2 4 6% 9% 69%	1800
	21st to end	Night	2 1 1 3 3 3 4 5% 6% 12% 60%	1969
August	1st to 10th	Night	2 1 1 2 3 2 3 5% 6% 13% 62%	1790
	11th to 20th	Night	3 2 2 4 5% 3 5% 6% 7% 13% 52%	1778
	21st to end	Night	4 3 2 3 4 4 6% 7% 7% 12% 49%	1980
September	1st to 10th	Night	6% 3 2 3 5% 4 5% 5% 6% 10% 52%	1800
	11th to 20th	Night	8% 4 2 4 4 2 4 6% 7% 10% 49%	1952
	21st to end	Night	8% 3 2 3 4 3 4 4 6% 10% 54%	1980
October	1st to 10th	Night	4 2 1 3 3 3 4 4 7% 7% 64%	1980
	11th to 20th	Night	7% 4 1 3 3 1 3 4 4 6% 63%	1996
	21st to end	Night	5% 3 1 2 2 1 2 2 2 4 74%	2376
November	1st to 10th	Night	7% 2 1 2 2 1 2 3 4 4 71%	2300
	11th to 20th	Night	5% 4 1 3 3 2 3 3 4 5% 68%	2470
	21st to end	Night	6% 4 2 3 4 2 3 4 5% 6% 62%	2470
December	1st to 10th	Night	7% 4 1 2 3 2 4 3 4 8% 61%	2470
	11th to 20th	Night	3 4 2 4 4 2 4 4 5% 7% 60%	3036
	21st to end	Night	3 5% 2 3 3 3 3 3 5% 8% 64%	4496

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	16% 1 6% 12% 29% 36%	3168
	11th to 20th	Day	15% 2 6% 15% 36% 26%	3170
	21st to end	Day	23% 4 6% 22% 31% 14%	3487
February	1st to 10th	Day	21% 3 6% 14% 26% 31%	1900
	11th to 20th	Day	24% 3 7% 14% 23% 29%	1859
	21st to end	Day	16% 3 5% 13% 28% 35%	1520
March	1st to 10th	Day	23% 4 7% 17% 23% 26%	1800
	11th to 20th	Day	27% 5% 6% 11% 22% 30%	1853
	21st to end	Day	17% 2 5% 12% 27% 37%	2376
April	1st to 10th	Day	17% 4 8% 12% 23% 36%	2160
	11th to 20th	Day	15% 3 7% 13% 24% 37%	2134
	21st to end	Day	19% 3 6% 13% 23% 37%	2160
May	1st to 10th	Day	16% 4 7% 13% 25% 36%	2160
	11th to 20th	Day	19% 5% 9% 19% 25% 24%	2136
	21st to end	Day	17% 6% 9% 22% 24% 23%	2531
June	1st to 10th	Day	12% 4 11% 26% 29% 18%	2340
	11th to 20th	Day	17% 5% 9% 18% 31% 20%	2340
	21st to end	Day	19% 7% 14% 21% 24% 15%	2340
July	1st to 10th	Day	28% 9% 17% 26% 16% 4	2150
	11th to 20th	Day	17% 6% 11% 28% 25% 12%	2097
	21st to end	Day	17% 8% 18% 34% 20% 3	2219
August	1st to 10th	Day	13% 7% 14% 32% 26% 7%	2136
	11th to 20th	Day	27% 9% 16% 26% 18% 4	2123
	21st to end	Day	24% 10% 15% 26% 17% 8%	2376
September	1st to 10th	Day	31% 7% 15% 21% 15% 10%	2160
	11th to 20th	Day	30% 8% 12% 20% 22% 8%	2006
	21st to end	Day	24% 6% 10% 18% 27% 14%	1980
October	1st to 10th	Day	17% 5% 11% 26% 22% 18%	1980
	11th to 20th	Day	24% 4 9% 18% 21% 24%	1959
	21st to end	Day	18% 3 4 16% 29% 31%	1980
November	1st to 10th	Day	17% 2 7% 20% 30% 23%	1756
	11th to 20th	Day	19% 3 8% 20% 28% 22%	1710
	21st to end	Day	23% 3 6% 22% 25% 22%	1710
December	1st to 10th	Day	25% 3 8% 19% 29% 16%	1710
	11th to 20th	Day	23% 4 6% 21% 29% 17%	2159
	21st to end	Day	17% 4 6% 15% 34% 24%	3199
January	1st to 10th	Night	14% 2 4 11% 33% 36%	3788
	11th to 20th	Night	15% 2 6% 12% 30% 35%	3800
	21st to end	Night	25% 4 6% 18% 30% 16%	4180
February	1st to 10th	Night	21% 3 6% 13% 26% 31%	2280
	11th to 20th	Night	24% 4 8% 13% 22% 30%	2218
	21st to end	Night	22% 3 6% 9% 26% 35%	1830
March	1st to 10th	Night	26% 3 8% 16% 23% 25%	2160
	11th to 20th	Night	25% 6% 7% 14% 18% 30%	2101
	21st to end	Night	19% 3 6% 14% 23% 35%	1980
April	1st to 10th	Night	21% 5% 6% 14% 21% 34%	1800
	11th to 20th	Night	18% 3 8% 16% 20% 34%	1777
	21st to end	Night	16% 4 7% 17% 24% 32%	1800
May	1st to 10th	Night	20% 4 9% 16% 20% 31%	1800
	11th to 20th	Night	25% 7% 8% 20% 22% 17%	1758
	21st to end	Night	23% 7% 12% 23% 19% 16%	1746
June	1st to 10th	Night	14% 6% 14% 30% 25% 12%	1620
	11th to 20th	Night	19% 7% 11% 21% 28% 15%	1620
	21st to end	Night	17% 6% 15% 23% 25% 15%	1620
July	1st to 10th	Night	25% 8% 21% 29% 15% 3	1694
	11th to 20th	Night	14% 5% 9% 34% 27% 11%	1740
	21st to end	Night	15% 8% 16% 36% 23% 1	1859
August	1st to 10th	Night	14% 6% 14% 31% 30% 5%	1779
	11th to 20th	Night	22% 8% 19% 30% 18% 3	1778
	21st to end	Night	24% 12% 15% 25% 17% 7%	1980
September	1st to 10th	Night	27% 8% 17% 26% 14% 10%	1800
	11th to 20th	Night	28% 9% 18% 20% 19% 6%	1952
	21st to end	Night	25% 6% 15% 21% 19% 13%	1980
October	1st to 10th	Night	18% 7% 15% 25% 19% 18%	1980
	11th to 20th	Night	22% 5% 8% 22% 20% 23%	1996
	21st to end	Night	18% 2 4 16% 30% 31%	2376
November	1st to 10th	Night	17% 3 6% 17% 31% 25%	2300
	11th to 20th	Night	20% 3 7% 18% 26% 26%	2470
	21st to end	Night	23% 4 9% 15% 22% 26%	2470
December	1st to 10th	Night	23% 4 7% 20% 25% 20%	2470
	11th to 20th	Night	23% 3 7% 20% 25% 22%	3037
	21st to end	Night	19% 4 6% 13% 33% 25%	4496

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	10% 8% 26% 39% 17%	270
	11th to 20th	Day	7% 9% 21% 40% 19% 3	270
	21st to end	Day	3 10% 24% 42% 18% 3	297
February	1st to 10th	Day	8% 7% 22% 34% 25% 3	270
	11th to 20th	Day	12% 9% 24% 37% 15% 3	270
	21st to end	Day	5% 12% 34% 39% 8% 2	210
March	1st to 10th	Day	5% 9% 29% 33% 23% 2	240
	11th to 20th	Day	9% 12% 30% 32% 14% 3	271
	21st to end	Day	6% 16% 33% 32% 12% 2	462
April	1st to 10th	Day	3 13% 38% 32% 12% 1	420
	11th to 20th	Day	4 18% 35% 29% 11% 3	412
	21st to end	Day	6% 15% 35% 34% 10% 1	420
May	1st to 10th	Day	2 12% 35% 32% 16% 3	423
	11th to 20th	Day	4 7% 30% 35% 19% 5%	456
	21st to end	Day	5% 5% 22% 39% 27% 3	679
June	1st to 10th	Day	2 2 18% 33% 38% 7%	630
	11th to 20th	Day	3 1 13% 32% 45% 7%	630
	21st to end	Day	4 1 11% 31% 41% 12%	630
July	1st to 10th	Day	5% 1 8% 26% 40% 21%	495
	11th to 20th	Day	1 9% 32% 37% 21%	444
	21st to end	Day	1 1 9% 37% 35% 17%	487
August	1st to 10th	Day	2 6% 30% 35% 28%	447
	11th to 20th	Day	8% 1 9% 31% 28% 23%	437
	21st to end	Day	4 1 7% 31% 34% 23%	495
September	1st to 10th	Day	7% 1 8% 36% 30% 17%	450
	11th to 20th	Day	6% 1 4 17% 42% 30%	296
	21st to end	Day	12% 6% 16% 40% 26%	270
October	1st to 10th	Day	5% 3 11% 25% 39% 17%	270
	11th to 20th	Day	12% 2 10% 27% 36% 13%	270
	21st to end	Day	8% 6% 15% 26% 31% 14%	297
November	1st to 10th	Day	11% 4 11% 31% 32% 11%	270
	11th to 20th	Day	10% 7% 16% 26% 31% 10%	270
	21st to end	Day	7% 11% 20% 34% 22% 5%	270
December	1st to 10th	Day	9% 5% 12% 33% 34% 8%	270
	11th to 20th	Day	6% 8% 26% 37% 20% 4	270
	21st to end	Day	5% 6% 26% 39% 22% 1	297
January	1st to 10th	Night	7% 3 21% 51% 16% 1	760
	11th to 20th	Night	9% 4 19% 50% 17% 1	760
	21st to end	Night	8% 4 23% 51% 14%	836
February	1st to 10th	Night	7% 4 25% 48% 16%	760
	11th to 20th	Night	7% 3 27% 51% 11% 1	744
	21st to end	Night	5% 7% 34% 48% 7%	610
March	1st to 10th	Night	8% 4 30% 48% 9% 1	720
	11th to 20th	Night	8% 5% 28% 45% 14% 1	697
	21st to end	Night	5% 5% 37% 42% 10%	594
April	1st to 10th	Night	5% 4 33% 49% 8%	540
	11th to 20th	Night	4 6% 40% 41% 8%	533
	21st to end	Night	3 6% 37% 46% 8%	540
May	1st to 10th	Night	5% 3 28% 53% 10%	540
	11th to 20th	Night	8% 4 26% 50% 13%	531
	21st to end	Night	4 3 25% 50% 18%	584
June	1st to 10th	Night	2 2 17% 54% 24%	540
	11th to 20th	Night	2 1 14% 48% 35%	540
	21st to end	Night	3 2 12% 45% 38%	540
July	1st to 10th	Night	6% 1 7% 38% 47% 2	525
	11th to 20th	Night	2 6% 37% 54% 2	522
	21st to end	Night	3 1 6% 36% 51% 3	591
August	1st to 10th	Night	2 5% 31% 58% 3	537
	11th to 20th	Night	2 6% 28% 59% 5%	534
	21st to end	Night	4 1 5% 34% 54% 2	594
September	1st to 10th	Night	6% 1 5% 38% 48% 2	540
	11th to 20th	Night	10% 5% 38% 45% 1	540
	21st to end	Night	9% 1 8% 43% 36% 3	540
October	1st to 10th	Night	5% 2 10% 47% 35% 1	540
	11th to 20th	Night	8% 1 12% 56% 21% 2	556
	21st to end	Night	7% 3 13% 45% 28% 4	792
November	1st to 10th	Night	9% 2 9% 47% 28% 5%	820
	11th to 20th	Night	7% 3 14% 49% 24% 3	950
	21st to end	Night	7% 3 22% 45% 20% 2	950
December	1st to 10th	Night	9% 3 15% 52% 21% 1	950
	11th to 20th	Night	6% 3 23% 53% 14% 1	950
	21st to end	Night	6% 4 22% 54% 14% 1	1022

Page generated at 2024-02-22 05:05:48. Version ac07

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