Franklinton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Franklinton clear sky chart from 2005-11-06 to 2024-01-13.

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	12% 6% 3 6% 6% 4 5% 6% 6% 7% 39%	74618
	Night	12% 6% 2 5% 4 3 4 5% 5% 8% 46%	75016
Transparency	Day	42% 5% 11% 18% 17% 6%	74354
	Night	36% 6% 12% 19% 18% 8%	74801
Seeing	Day	15% 8% 19% 25% 22% 11%	13665
	Night	15% 7% 21% 29% 22% 6%	23438

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	18% 7% 2 5% 4 3 4 4 4 6% 44%	1707
	11th to 20th	Day	17% 7% 3 5% 4 3 4 4 5% 5% 44%	1638
	21st to end	Day	19% 7% 3 5% 4 3 4 4 4 4 45%	1946
February	1st to 10th	Day	18% 9% 4 6% 5% 2 4 4 4 6% 39%	1800
	11th to 20th	Day	18% 7% 2 5% 4 2 4 4 4 7% 42%	1748
	21st to end	Day	18% 8% 3 7% 5% 3 4 4 5% 6% 36%	1480
March	1st to 10th	Day	17% 6% 3 6% 5% 3 3 5% 5% 7% 41%	1879
	11th to 20th	Day	15% 7% 3 7% 5% 4 5% 4 5% 7% 38%	1980
	21st to end	Day	11% 6% 2 6% 5% 3 5% 5% 6% 6% 44%	2283
April	1st to 10th	Day	11% 7% 3 5% 6% 4 5% 5% 7% 8% 40%	2160
	11th to 20th	Day	15% 6% 3 5% 5% 4 5% 4 5% 7% 40%	2134
	21st to end	Day	10% 5% 2 4 5% 4 6% 5% 5% 8% 46%	2160
May	1st to 10th	Day	12% 5% 3 5% 5% 3 5% 5% 6% 8% 43%	2160
	11th to 20th	Day	10% 7% 2 6% 6% 4 5% 7% 5% 8% 41%	2124
	21st to end	Day	8% 5% 3 7% 7% 5% 6% 8% 8% 9% 35%	2337
June	1st to 10th	Day	10% 6% 3 7% 8% 5% 7% 7% 7% 9% 30%	2204
	11th to 20th	Day	5% 5% 2 7% 8% 5% 7% 8% 9% 12% 32%	2396
	21st to end	Day	8% 7% 3 6% 9% 6% 8% 9% 8% 10% 26%	2340
July	1st to 10th	Day	9% 7% 4 8% 9% 6% 9% 8% 8% 9% 24%	2340
	11th to 20th	Day	9% 5% 3 6% 10% 6% 10% 8% 9% 10% 24%	2340
	21st to end	Day	9% 7% 3 6% 8% 5% 8% 6% 8% 10% 29%	2350
August	1st to 10th	Day	6% 5% 2 7% 8% 5% 7% 8% 8% 10% 34%	2148
	11th to 20th	Day	11% 7% 3 8% 8% 5% 6% 7% 6% 9% 30%	2125
	21st to end	Day	12% 5% 2 6% 7% 5% 7% 7% 7% 10% 32%	2376
September	1st to 10th	Day	10% 6% 3 7% 7% 5% 7% 7% 6% 8% 34%	2160
	11th to 20th	Day	11% 6% 3 5% 6% 3 7% 7% 6% 7% 39%	2106
	21st to end	Day	9% 5% 2 4 6% 3 5% 5% 5% 6% 49%	1980
October	1st to 10th	Day	7% 4 1 4 5% 3 4 5% 5% 6% 55%	1898
	11th to 20th	Day	7% 4 3 5% 6% 2 4 4 5% 7% 53%	1800
	21st to end	Day	10% 4 2 4 5% 3 3 5% 5% 5% 55%	1980
November	1st to 10th	Day	9% 5% 2 5% 4 3 4 4 4 6% 53%	1858
	11th to 20th	Day	11% 5% 2 5% 4 3 3 4 5% 5% 53%	1789
	21st to end	Day	14% 6% 3 5% 4 3 4 4 5% 6% 45%	1710
December	1st to 10th	Day	16% 6% 3 5% 3 3 4 6% 4 6% 43%	1710
	11th to 20th	Day	16% 9% 3 5% 6% 3 4 3 6% 5% 40%	2153
	21st to end	Day	17% 8% 3 5% 5% 3 4 5% 6% 7% 38%	3319
January	1st to 10th	Night	18% 6% 2 4 4 2 3 4 5% 6% 47%	2458
	11th to 20th	Night	19% 6% 3 5% 4 2 3 3 4 5% 45%	2367
	21st to end	Night	20% 7% 3 5% 4 3 4 3 3 5% 43%	2403
February	1st to 10th	Night	18% 7% 3 5% 4 3 4 3 5% 6% 41%	2160
	11th to 20th	Night	20% 7% 2 5% 5% 3 3 4 4 6% 42%	2098
	21st to end	Night	21% 7% 4 6% 5% 3 3 4 5% 7% 36%	1776
March	1st to 10th	Night	14% 6% 3 5% 5% 2 4 4 4 8% 45%	2095
	11th to 20th	Night	15% 7% 3 5% 5% 3 5% 4 6% 7% 39%	1980
	21st to end	Night	13% 5% 2 4 3 3 4 4 4 7% 51%	2071
April	1st to 10th	Night	14% 6% 3 5% 5% 3 4 4 4 8% 45%	1800
	11th to 20th	Night	14% 6% 2 5% 4 3 5% 4 4 7% 45%	1775
	21st to end	Night	8% 3 2 4 4 2 4 4 5% 7% 58%	1800
May	1st to 10th	Night	10% 3 1 3 4 3 4 4 6% 7% 55%	1800
	11th to 20th	Night	7% 5% 2 5% 5% 4 4 6% 6% 10% 47%	1769
	21st to end	Night	7% 4 2 4 4 4 5% 7% 7% 11% 46%	1938
June	1st to 10th	Night	7% 6% 3 6% 6% 3 5% 6% 7% 12% 39%	1717
	11th to 20th	Night	4 2 2 5% 4 3 6% 7% 7% 13% 48%	1533
	21st to end	Night	7% 5% 2 6% 7% 3 6% 7% 7% 10% 40%	1620
July	1st to 10th	Night	6% 4 3 5% 5% 4 6% 6% 10% 14% 37%	1620
	11th to 20th	Night	4 4 2 5% 7% 3 7% 7% 9% 14% 37%	1620
	21st to end	Night	6% 4 2 5% 5% 4 7% 5% 9% 13% 39%	1963
August	1st to 10th	Night	4 3 2 4 4 3 5% 8% 8% 13% 46%	1790
	11th to 20th	Night	6% 5% 2 5% 6% 4 7% 8% 7% 13% 38%	1776
	21st to end	Night	8% 6% 2 5% 5% 3 6% 6% 8% 11% 39%	1980
September	1st to 10th	Night	7% 5% 3 5% 5% 4 5% 5% 8% 11% 42%	1800
	11th to 20th	Night	9% 5% 2 5% 5% 3 6% 6% 7% 8% 45%	1835
	21st to end	Night	8% 5% 2 5% 5% 4 4 4 5% 7% 50%	1980
October	1st to 10th	Night	7% 3 2 4 4 3 4 3 5% 7% 58%	2057
	11th to 20th	Night	7% 4 2 4 3 2 3 4 5% 7% 59%	2160
	21st to end	Night	12% 4 2 4 3 2 3 3 4 5% 56%	2376
November	1st to 10th	Night	11% 4 2 4 4 3 3 4 4 5% 57%	2220
	11th to 20th	Night	14% 4 2 3 3 2 3 4 5% 5% 54%	2385
	21st to end	Night	14% 7% 2 4 5% 2 4 3 5% 6% 47%	2470
December	1st to 10th	Night	16% 8% 3 5% 4 2 4 3 4 6% 45%	2470
	11th to 20th	Night	15% 9% 3 5% 5% 3 5% 4 4 6% 42%	3042
	21st to end	Night	19% 9% 3 6% 5% 2 3 3 3 5% 41%	4312

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	42% 4 5% 17% 23% 9%	1708
	11th to 20th	Day	42% 3 4 16% 25% 10%	1638
	21st to end	Day	43% 3 5% 16% 22% 11%	1946
February	1st to 10th	Day	48% 4 7% 14% 18% 10%	1800
	11th to 20th	Day	42% 4 6% 18% 20% 10%	1758
	21st to end	Day	50% 3 7% 14% 17% 9%	1480
March	1st to 10th	Day	43% 3 6% 18% 20% 8%	1879
	11th to 20th	Day	46% 4 10% 13% 20% 8%	1980
	21st to end	Day	39% 4 11% 19% 21% 6%	2283
April	1st to 10th	Day	40% 5% 10% 18% 19% 8%	2160
	11th to 20th	Day	43% 4 7% 19% 18% 8%	2134
	21st to end	Day	35% 5% 9% 23% 23% 5%	2160
May	1st to 10th	Day	37% 4 11% 21% 20% 7%	2160
	11th to 20th	Day	41% 5% 12% 22% 19% 2	2128
	21st to end	Day	41% 7% 13% 23% 14% 2	2337
June	1st to 10th	Day	48% 7% 12% 23% 9% 1	2204
	11th to 20th	Day	41% 8% 16% 21% 12% 2	2396
	21st to end	Day	49% 9% 15% 19% 6% 1	2340
July	1st to 10th	Day	53% 10% 17% 15% 5% 1	2276
	11th to 20th	Day	50% 10% 19% 16% 4 1	2271
	21st to end	Day	47% 9% 19% 18% 6% 1	2219
August	1st to 10th	Day	42% 10% 22% 17% 9%	2136
	11th to 20th	Day	49% 10% 17% 17% 6% 2	2125
	21st to end	Day	47% 7% 17% 16% 10% 2	2376
September	1st to 10th	Day	45% 8% 13% 18% 13% 4	2160
	11th to 20th	Day	42% 7% 12% 17% 15% 7%	2106
	21st to end	Day	35% 5% 9% 22% 19% 9%	1980
October	1st to 10th	Day	30% 4 10% 20% 23% 13%	1898
	11th to 20th	Day	31% 4 6% 17% 28% 14%	1800
	21st to end	Day	30% 4 5% 18% 27% 16%	1980
November	1st to 10th	Day	32% 3 6% 19% 27% 13%	1858
	11th to 20th	Day	32% 3 6% 17% 29% 12%	1789
	21st to end	Day	40% 3 6% 17% 23% 11%	1710
December	1st to 10th	Day	42% 4 9% 18% 20% 8%	1710
	11th to 20th	Day	46% 3 7% 13% 24% 8%	2150
	21st to end	Day	45% 3 9% 18% 22% 3	3319
January	1st to 10th	Night	39% 3 7% 17% 25% 9%	2458
	11th to 20th	Night	42% 4 5% 19% 21% 10%	2367
	21st to end	Night	45% 3 4 12% 25% 10%	2403
February	1st to 10th	Night	44% 3 6% 17% 19% 10%	2160
	11th to 20th	Night	45% 4 4 15% 20% 12%	2099
	21st to end	Night	48% 4 8% 13% 13% 12%	1776
March	1st to 10th	Night	40% 4 8% 16% 22% 10%	2095
	11th to 20th	Night	43% 6% 11% 16% 18% 7%	1980
	21st to end	Night	34% 5% 10% 21% 24% 7%	2071
April	1st to 10th	Night	40% 4 10% 18% 18% 10%	1800
	11th to 20th	Night	41% 3 9% 20% 19% 9%	1775
	21st to end	Night	27% 5% 12% 23% 27% 8%	1800
May	1st to 10th	Night	29% 3 11% 28% 23% 7%	1800
	11th to 20th	Night	32% 7% 17% 22% 19% 2	1770
	21st to end	Night	29% 7% 18% 28% 15% 2	1939
June	1st to 10th	Night	36% 7% 17% 28% 12% 1	1717
	11th to 20th	Night	26% 10% 20% 29% 13% 2	1533
	21st to end	Night	37% 8% 21% 24% 9% 1	1620
July	1st to 10th	Night	32% 15% 27% 19% 6% 1	1575
	11th to 20th	Night	32% 15% 31% 18% 3 1	1566
	21st to end	Night	32% 14% 26% 22% 6%	1854
August	1st to 10th	Night	25% 11% 34% 20% 9% 1	1778
	11th to 20th	Night	35% 13% 25% 19% 6% 1	1776
	21st to end	Night	37% 10% 23% 17% 9% 4	1980
September	1st to 10th	Night	35% 8% 21% 18% 12% 7%	1800
	11th to 20th	Night	35% 8% 17% 19% 14% 9%	1835
	21st to end	Night	33% 5% 11% 25% 16% 10%	1980
October	1st to 10th	Night	26% 4 10% 20% 23% 16%	2057
	11th to 20th	Night	27% 4 7% 21% 27% 14%	2160
	21st to end	Night	31% 3 5% 17% 27% 18%	2376
November	1st to 10th	Night	30% 3 8% 19% 25% 16%	2220
	11th to 20th	Night	31% 3 7% 16% 27% 16%	2385
	21st to end	Night	38% 3 6% 19% 20% 13%	2470
December	1st to 10th	Night	41% 4 8% 21% 20% 7%	2470
	11th to 20th	Night	45% 3 6% 13% 20% 13%	3044
	21st to end	Night	47% 3 6% 17% 19% 7%	4312

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	27% 15% 35% 18% 4 1	270
	11th to 20th	Day	23% 15% 36% 19% 7%	246
	21st to end	Day	30% 21% 33% 13% 3	264
February	1st to 10th	Day	30% 18% 34% 15% 4	240
	11th to 20th	Day	33% 15% 31% 16% 4	240
	21st to end	Day	24% 26% 36% 12% 3	198
March	1st to 10th	Day	20% 18% 38% 22% 2	240
	11th to 20th	Day	25% 23% 34% 14% 5%	240
	21st to end	Day	21% 15% 34% 21% 8% 1	369
April	1st to 10th	Day	19% 14% 31% 24% 11% 1	420
	11th to 20th	Day	22% 13% 29% 23% 11% 1	412
	21st to end	Day	12% 10% 32% 30% 15% 2	420
May	1st to 10th	Day	14% 8% 28% 28% 18% 4	423
	11th to 20th	Day	15% 3 22% 31% 21% 9%	447
	21st to end	Day	8% 2 16% 34% 28% 12%	485
June	1st to 10th	Day	14% 3 10% 30% 28% 15%	452
	11th to 20th	Day	7% 3 12% 36% 31% 11%	630
	21st to end	Day	11% 3 10% 29% 32% 16%	630
July	1st to 10th	Day	10% 2 5% 26% 38% 20%	621
	11th to 20th	Day	9% 2 3 23% 40% 23%	618
	21st to end	Day	12% 2 3 21% 35% 27%	488
August	1st to 10th	Day	4 2 4 19% 39% 31%	446
	11th to 20th	Day	9% 3 4 17% 38% 30%	439
	21st to end	Day	12% 4 8% 19% 32% 25%	495
September	1st to 10th	Day	9% 2 6% 24% 38% 20%	450
	11th to 20th	Day	10% 5% 10% 25% 34% 16%	450
	21st to end	Day	11% 4 10% 31% 34% 10%	450
October	1st to 10th	Day	8% 5% 20% 37% 23% 7%	368
	11th to 20th	Day	8% 7% 23% 32% 24% 6%	270
	21st to end	Day	19% 10% 20% 32% 16% 3	297
November	1st to 10th	Day	16% 6% 23% 40% 12% 3	270
	11th to 20th	Day	17% 13% 32% 24% 13% 1	270
	21st to end	Day	16% 15% 35% 21% 8% 4	270
December	1st to 10th	Day	22% 9% 36% 21% 10% 1	270
	11th to 20th	Day	23% 16% 39% 16% 6% 1	270
	21st to end	Day	27% 14% 32% 20% 7% 1	297
January	1st to 10th	Night	23% 12% 32% 27% 7%	950
	11th to 20th	Night	23% 11% 31% 26% 8% 1	911
	21st to end	Night	24% 14% 31% 27% 4	819
February	1st to 10th	Night	23% 10% 35% 27% 4	720
	11th to 20th	Night	25% 14% 28% 26% 6%	703
	21st to end	Night	25% 14% 36% 23% 2	592
March	1st to 10th	Night	19% 14% 32% 28% 7%	655
	11th to 20th	Night	19% 9% 31% 31% 9%	540
	21st to end	Night	17% 12% 31% 29% 11%	594
April	1st to 10th	Night	18% 11% 30% 29% 13% 1	540
	11th to 20th	Night	18% 8% 31% 29% 13% 1	533
	21st to end	Night	10% 5% 29% 41% 15%	540
May	1st to 10th	Night	11% 4 27% 39% 19%	540
	11th to 20th	Night	9% 2 22% 38% 25% 3	531
	21st to end	Night	7% 2 15% 37% 31% 8%	584
June	1st to 10th	Night	8% 2 8% 36% 38% 7%	540
	11th to 20th	Night	4 1 6% 35% 44% 11%	540
	21st to end	Night	8% 2 8% 28% 40% 15%	540
July	1st to 10th	Night	7% 2 3 21% 48% 19%	525
	11th to 20th	Night	5% 2 19% 49% 25%	522
	21st to end	Night	6% 1 3 21% 48% 21%	591
August	1st to 10th	Night	5% 1 3 18% 46% 27%	537
	11th to 20th	Night	7% 1 1 16% 49% 24%	534
	21st to end	Night	10% 2 5% 19% 40% 24%	594
September	1st to 10th	Night	8% 3 6% 24% 42% 17%	540
	11th to 20th	Night	11% 3 7% 25% 43% 11%	575
	21st to end	Night	11% 3 8% 32% 39% 7%	720
October	1st to 10th	Night	8% 3 17% 34% 33% 5%	720
	11th to 20th	Night	10% 3 20% 37% 26% 3	720
	21st to end	Night	15% 7% 22% 34% 20% 3	792
November	1st to 10th	Night	14% 6% 19% 39% 20% 2	740
	11th to 20th	Night	16% 7% 28% 33% 14% 1	760
	21st to end	Night	17% 8% 28% 31% 15% 1	760
December	1st to 10th	Night	19% 12% 28% 28% 13%	760
	11th to 20th	Night	23% 7% 32% 29% 9%	760
	21st to end	Night	28% 11% 27% 28% 6%	916

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