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 2026-10-29.

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	13% 6% 2 6% 4 4 4 4 6% 8% 42%	148313
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 44%	143728
Transparency	Day	39% 5% 13% 22% 17% 5%	151917
	Night	39% 4 10% 20% 20% 6%	148197
Seeing	Day	18% 11% 27% 24% 15% 5%	17945
	Night	17% 10% 26% 30% 15% 2	28081

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 5% 3 3 2 2 4 5% 54%	5258
	11th to 20th	Day	12% 6% 2 4 3 2 3 2 3 4 59%	5280
	21st to end	Day	16% 8% 3 7% 4 4 3 3 4 5% 45%	5780
February	1st to 10th	Day	13% 7% 2 7% 4 4 4 3 6% 8% 43%	1890
	11th to 20th	Day	21% 7% 2 4 4 3 4 3 4 5% 43%	1880
	21st to end	Day	18% 7% 3 6% 5% 3 3 2 5% 5% 42%	1845
March	1st to 10th	Day	19% 8% 3 6% 4 4 4 3 5% 6% 39%	5045
	11th to 20th	Day	11% 5% 2 5% 4 3 3 3 5% 6% 53%	5090
	21st to end	Day	15% 5% 2 6% 4 4 5% 3 5% 6% 46%	5586
April	1st to 10th	Day	11% 4 2 4 3 3 4 3 5% 7% 53%	2467
	11th to 20th	Day	10% 4 2 5% 4 4 3 4 6% 8% 49%	2494
	21st to end	Day	14% 6% 1 5% 4 5% 4 4 6% 6% 45%	2520
May	1st to 10th	Day	12% 6% 3 7% 5% 5% 5% 4 7% 9% 37%	7455
	11th to 20th	Day	15% 6% 2 7% 4 4 4 4 6% 7% 40%	7626
	21st to end	Day	15% 5% 2 6% 5% 4 5% 5% 6% 8% 37%	8391
June	1st to 10th	Day	9% 5% 3 6% 5% 5% 5% 4 7% 9% 42%	2806
	11th to 20th	Day	8% 5% 2 6% 4 5% 5% 5% 7% 10% 45%	2897
	21st to end	Day	8% 5% 2 5% 5% 6% 6% 5% 8% 11% 39%	2730
July	1st to 10th	Day	7% 4 2 7% 5% 6% 6% 6% 9% 13% 36%	7680
	11th to 20th	Day	11% 6% 3 7% 6% 6% 6% 5% 8% 12% 30%	7680
	21st to end	Day	12% 6% 3 7% 5% 5% 6% 5% 8% 11% 33%	8340
August	1st to 10th	Day	16% 7% 3 9% 6% 6% 6% 6% 9% 11% 21%	6014
	11th to 20th	Day	7% 5% 2 7% 5% 5% 5% 5% 8% 13% 38%	5718
	21st to end	Day	9% 5% 2 6% 4 4 4 4 6% 10% 46%	6080
September	1st to 10th	Day	9% 5% 3 6% 4 5% 5% 4 6% 8% 47%	2520
	11th to 20th	Day	15% 6% 2 6% 5% 4 4 4 6% 8% 42%	2426
	21st to end	Day	21% 7% 3 5% 3 3 4 4 5% 8% 38%	2239
October	1st to 10th	Day	16% 6% 2 6% 4 3 3 3 4 6% 48%	2100
	11th to 20th	Day	14% 5% 1 4 2 2 3 3 4 5% 57%	2100
	21st to end	Day	11% 4 2 4 4 3 3 2 4 5% 58%	2280
November	1st to 10th	Day	12% 6% 1 6% 3 4 3 2 4 6% 54%	2057
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 6% 5% 52%	2079
	21st to end	Day	14% 5% 2 4 3 3 2 4 5% 7% 51%	1694
December	1st to 10th	Day	13% 6% 2 5% 4 4 3 3 4 5% 52%	2680
	11th to 20th	Day	16% 6% 3 7% 4 4 3 3 4 5% 46%	3070
	21st to end	Day	15% 6% 2 6% 3 3 4 3 5% 7% 46%	4516
January	1st to 10th	Night	11% 6% 2 5% 3 3 4 3 5% 6% 52%	7635
	11th to 20th	Night	12% 6% 2 5% 3 2 2 2 3 5% 57%	7680
	21st to end	Night	17% 8% 2 6% 4 3 3 3 4 5% 46%	8401
February	1st to 10th	Night	17% 6% 2 5% 3 4 4 3 5% 6% 44%	2730
	11th to 20th	Night	20% 7% 2 6% 4 4 4 3 4 6% 41%	2625
	21st to end	Night	14% 6% 2 5% 4 4 4 4 5% 5% 47%	1955
March	1st to 10th	Night	18% 8% 2 6% 4 3 4 3 4 4 42%	5028
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 5% 6% 54%	5090
	21st to end	Night	13% 5% 2 4 3 4 4 3 5% 7% 50%	5588
April	1st to 10th	Night	14% 5% 1 5% 3 4 3 3 5% 7% 49%	2153
	11th to 20th	Night	12% 5% 1 5% 4 3 3 3 6% 7% 50%	2075
	21st to end	Night	12% 4 2 6% 5% 5% 4 4 5% 7% 46%	2100
May	1st to 10th	Night	11% 7% 3 7% 5% 4 5% 4 6% 9% 38%	5439
	11th to 20th	Night	16% 7% 3 7% 4 4 4 3 4 7% 42%	5234
	21st to end	Night	19% 7% 2 7% 4 4 4 4 5% 8% 35%	5761
June	1st to 10th	Night	10% 6% 2 6% 5% 5% 5% 5% 7% 11% 40%	1796
	11th to 20th	Night	9% 6% 2 6% 5% 4 6% 4 6% 10% 41%	1703
	21st to end	Night	7% 6% 2 5% 5% 5% 5% 5% 8% 10% 41%	1890
July	1st to 10th	Night	10% 5% 3 7% 5% 5% 6% 4 8% 11% 36%	5278
	11th to 20th	Night	15% 6% 3 8% 5% 6% 6% 5% 8% 11% 28%	5277
	21st to end	Night	14% 7% 4 8% 5% 5% 5% 5% 7% 10% 30%	5736
August	1st to 10th	Night	19% 8% 3 8% 5% 5% 5% 5% 8% 11% 22%	4135
	11th to 20th	Night	7% 6% 3 7% 5% 6% 6% 5% 8% 11% 37%	4280
	21st to end	Night	9% 6% 3 7% 4 4 5% 3 6% 9% 44%	5045
September	1st to 10th	Night	10% 6% 2 5% 4 4 4 4 5% 8% 48%	2100
	11th to 20th	Night	13% 7% 3 7% 4 5% 4 3 5% 6% 43%	2190
	21st to end	Night	21% 7% 3 8% 4 4 4 3 5% 6% 36%	2379
October	1st to 10th	Night	15% 6% 2 6% 4 3 3 3 5% 6% 48%	2520
	11th to 20th	Night	14% 6% 2 4 3 3 3 3 4 4 55%	2520
	21st to end	Night	12% 5% 2 5% 3 3 3 2 4 5% 57%	2737
November	1st to 10th	Night	13% 6% 2 6% 3 3 3 2 5% 5% 52%	2461
	11th to 20th	Night	13% 5% 2 5% 4 3 4 3 6% 6% 50%	2536
	21st to end	Night	12% 5% 2 5% 4 3 3 3 6% 6% 52%	2924
December	1st to 10th	Night	11% 6% 2 6% 4 4 3 3 4 5% 52%	4720
	11th to 20th	Night	17% 7% 3 8% 4 4 4 4 5% 5% 40%	5345
	21st to end	Night	15% 6% 2 5% 3 3 3 3 5% 6% 48%	6662

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	35% 1 10% 21% 26% 6%	5259
	11th to 20th	Day	31% 2 4 15% 37% 11%	5280
	21st to end	Day	43% 2 5% 23% 19% 8%	5780
February	1st to 10th	Day	39% 4 11% 22% 19% 6%	1890
	11th to 20th	Day	44% 4 7% 18% 21% 6%	1889
	21st to end	Day	45% 4 10% 16% 20% 5%	1845
March	1st to 10th	Day	46% 4 6% 18% 16% 10%	5045
	11th to 20th	Day	33% 4 7% 19% 24% 14%	5090
	21st to end	Day	40% 3 10% 21% 19% 6%	5586
April	1st to 10th	Day	31% 4 11% 25% 21% 8%	2467
	11th to 20th	Day	32% 4 13% 24% 21% 6%	2494
	21st to end	Day	38% 5% 11% 24% 18% 4	2520
May	1st to 10th	Day	42% 5% 16% 22% 12% 2	7489
	11th to 20th	Day	43% 4 13% 24% 15% 1	7630
	21st to end	Day	44% 6% 12% 20% 15% 3	8405
June	1st to 10th	Day	37% 7% 14% 24% 16% 2	2806
	11th to 20th	Day	33% 8% 17% 25% 15% 1	2897
	21st to end	Day	36% 8% 16% 23% 15% 2	2730
July	1st to 10th	Day	38% 6% 20% 26% 9% 2	7615
	11th to 20th	Day	46% 6% 24% 15% 7% 1	7611
	21st to end	Day	45% 6% 15% 21% 13%	8156
August	1st to 10th	Day	54% 8% 22% 12% 3	6001
	11th to 20th	Day	37% 6% 24% 25% 8%	5757
	21st to end	Day	35% 4 14% 32% 14% 1	6080
September	1st to 10th	Day	35% 7% 14% 21% 20% 4	2520
	11th to 20th	Day	40% 5% 10% 21% 20% 3	2426
	21st to end	Day	45% 5% 11% 20% 15% 4	2239
October	1st to 10th	Day	36% 2 7% 21% 26% 7%	3360
	11th to 20th	Day	22% 2 5% 21% 29% 22%	3340
	21st to end	Day	24% 2 7% 26% 26% 16%	3618
November	1st to 10th	Day	34% 2 7% 23% 27% 6%	2057
	11th to 20th	Day	33% 3 9% 23% 25% 7%	2079
	21st to end	Day	34% 3 9% 23% 26% 5%	1694
December	1st to 10th	Day	36% 4 7% 22% 25% 7%	2680
	11th to 20th	Day	42% 3 10% 20% 20% 5%	3066
	21st to end	Day	39% 3 12% 26% 18% 1	4516
January	1st to 10th	Night	34% 2 10% 21% 24% 9%	7636
	11th to 20th	Night	33% 2 4 16% 35% 9%	7680
	21st to end	Night	42% 2 4 19% 25% 7%	8401
February	1st to 10th	Night	41% 4 9% 21% 21% 5%	2730
	11th to 20th	Night	45% 4 8% 17% 20% 7%	2627
	21st to end	Night	38% 5% 8% 20% 21% 8%	1955
March	1st to 10th	Night	45% 3 6% 14% 21% 10%	5028
	11th to 20th	Night	33% 3 7% 16% 24% 17%	5090
	21st to end	Night	35% 3 9% 24% 23% 6%	5588
April	1st to 10th	Night	35% 5% 10% 20% 24% 7%	2153
	11th to 20th	Night	33% 4 10% 25% 22% 7%	2075
	21st to end	Night	36% 5% 10% 26% 18% 4	2100
May	1st to 10th	Night	43% 5% 15% 22% 14% 2	5468
	11th to 20th	Night	43% 5% 12% 23% 18% 1	5235
	21st to end	Night	48% 5% 11% 20% 14% 1	5771
June	1st to 10th	Night	37% 9% 15% 20% 17% 2	1796
	11th to 20th	Night	38% 8% 16% 21% 16% 2	1703
	21st to end	Night	35% 10% 15% 22% 16% 2	1890
July	1st to 10th	Night	42% 7% 18% 23% 10% 1	5235
	11th to 20th	Night	50% 10% 19% 12% 7% 1	5226
	21st to end	Night	49% 6% 15% 18% 12% 1	5606
August	1st to 10th	Night	55% 10% 18% 13% 4	4124
	11th to 20th	Night	40% 5% 21% 26% 6% 1	4307
	21st to end	Night	37% 4 10% 28% 19% 1	5045
September	1st to 10th	Night	34% 8% 13% 24% 17% 4	2100
	11th to 20th	Night	41% 6% 11% 20% 20% 2	2190
	21st to end	Night	50% 6% 12% 15% 15% 4	2379
October	1st to 10th	Night	39% 3 7% 21% 25% 5%	4040
	11th to 20th	Night	26% 3 5% 19% 27% 20%	4019
	21st to end	Night	23% 2 6% 29% 23% 16%	4349
November	1st to 10th	Night	35% 3 8% 20% 27% 7%	2461
	11th to 20th	Night	35% 4 8% 17% 25% 10%	2536
	21st to end	Night	34% 4 7% 23% 26% 7%	2924
December	1st to 10th	Night	36% 3 6% 20% 28% 6%	4720
	11th to 20th	Night	47% 3 9% 18% 17% 7%	5348
	21st to end	Night	37% 3 12% 26% 20% 2	6662

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	26% 27% 34% 11% 2	330
	11th to 20th	Day	28% 27% 32% 9% 3	330
	21st to end	Day	21% 26% 40% 10% 2	363
February	1st to 10th	Day	20% 24% 41% 13% 2	330
	11th to 20th	Day	39% 24% 28% 8% 1	367
	21st to end	Day	26% 21% 33% 17% 4	446
March	1st to 10th	Day	24% 22% 31% 18% 6%	540
	11th to 20th	Day	24% 20% 37% 14% 5%	540
	21st to end	Day	21% 19% 40% 15% 4 1	594
April	1st to 10th	Day	21% 18% 36% 19% 7%	540
	11th to 20th	Day	16% 16% 37% 21% 7% 3	532
	21st to end	Day	18% 11% 32% 26% 13% 1	540
May	1st to 10th	Day	17% 17% 35% 21% 8% 2	543
	11th to 20th	Day	18% 9% 27% 27% 16% 2	567
	21st to end	Day	19% 6% 25% 25% 19% 5%	617
June	1st to 10th	Day	11% 6% 27% 33% 18% 6%	570
	11th to 20th	Day	10% 5% 24% 31% 24% 6%	570
	21st to end	Day	8% 4 20% 37% 25% 6%	570
July	1st to 10th	Day	11% 1 11% 35% 32% 10%	565
	11th to 20th	Day	7% 2 11% 34% 36% 10%	564
	21st to end	Day	11% 2 18% 35% 27% 8%	620
August	1st to 10th	Day	15% 3 20% 32% 22% 8%	566
	11th to 20th	Day	12% 2 14% 32% 30% 11%	559
	21st to end	Day	10% 3 14% 32% 26% 15%	627
September	1st to 10th	Day	12% 4 16% 28% 27% 13%	570
	11th to 20th	Day	17% 5% 15% 30% 22% 11%	570
	21st to end	Day	26% 6% 23% 26% 14% 4	570
October	1st to 10th	Day	21% 6% 21% 25% 20% 8%	570
	11th to 20th	Day	16% 12% 27% 26% 15% 4	570
	21st to end	Day	16% 13% 25% 27% 16% 3	615
November	1st to 10th	Day	18% 10% 33% 23% 13% 3	535
	11th to 20th	Day	18% 17% 30% 24% 9% 1	529
	21st to end	Day	21% 20% 26% 20% 12% 1	234
December	1st to 10th	Day	24% 19% 41% 11% 5%	220
	11th to 20th	Day	21% 16% 35% 22% 5% 1	220
	21st to end	Day	24% 18% 35% 14% 7% 1	352
January	1st to 10th	Night	20% 21% 32% 23% 3	840
	11th to 20th	Night	22% 17% 35% 22% 5%	840
	21st to end	Night	20% 17% 37% 24% 3	924
February	1st to 10th	Night	21% 16% 37% 22% 4	840
	11th to 20th	Night	25% 23% 34% 17% 1	823
	21st to end	Night	20% 17% 36% 24% 2	692
March	1st to 10th	Night	20% 16% 34% 26% 5%	840
	11th to 20th	Night	19% 18% 35% 21% 7%	840
	21st to end	Night	18% 14% 42% 21% 5%	924
April	1st to 10th	Night	18% 18% 34% 25% 5%	840
	11th to 20th	Night	15% 12% 38% 26% 9%	831
	21st to end	Night	14% 9% 37% 32% 7%	840
May	1st to 10th	Night	11% 13% 37% 33% 6%	704
	11th to 20th	Night	17% 7% 26% 34% 14% 1	621
	21st to end	Night	16% 3 19% 37% 23% 2	683
June	1st to 10th	Night	12% 2 23% 40% 22% 1	536
	11th to 20th	Night	11% 3 20% 41% 21% 4	443
	21st to end	Night	8% 3 15% 43% 28% 3	630
July	1st to 10th	Night	10% 1 12% 42% 32% 4	615
	11th to 20th	Night	9% 1 8% 39% 35% 7%	612
	21st to end	Night	11% 2 14% 39% 29% 4	690
August	1st to 10th	Night	14% 3 11% 41% 29% 2	627
	11th to 20th	Night	12% 2 10% 38% 34% 4	705
	21st to end	Night	11% 2 12% 34% 34% 6%	924
September	1st to 10th	Night	13% 2 12% 36% 33% 5%	840
	11th to 20th	Night	16% 3 13% 35% 28% 3	840
	21st to end	Night	24% 4 20% 31% 20% 1	840
October	1st to 10th	Night	18% 4 18% 28% 26% 5%	840
	11th to 20th	Night	16% 10% 25% 28% 18% 2	840
	21st to end	Night	14% 11% 24% 30% 19% 2	913
November	1st to 10th	Night	16% 9% 29% 31% 13% 2	820
	11th to 20th	Night	16% 13% 29% 30% 10%	840
	21st to end	Night	15% 15% 27% 30% 13% 1	840
December	1st to 10th	Night	21% 13% 31% 27% 7%	840
	11th to 20th	Night	19% 11% 32% 30% 7%	840
	21st to end	Night	22% 16% 27% 28% 6%	924

Page generated at 2026-10-26 04:37:47. Version ac07

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