Lititz
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lititz clear sky chart from 2005-11-06 to 2024-03-06.

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% 3 5% 5% 3 5% 5% 6% 8% 40%	78506
	Night	16% 6% 2 5% 5% 3 4 5% 5% 7% 41%	80985
Transparency	Day	42% 7% 12% 22% 14% 2	78218
	Night	41% 6% 12% 23% 15% 2	80807
Seeing	Day	20% 14% 27% 22% 12% 4	13953
	Night	18% 11% 30% 29% 11% 1	23467

By Month

Percentage Cloud Cover NE (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	15% 7% 3 5% 5% 3 4 4 4 6% 43%	2517
	11th to 20th	Day	15% 11% 4 8% 7% 3 4 5% 6% 6% 32%	2694
	21st to end	Day	20% 10% 4 7% 6% 3 4 4 4 5% 32%	3124
February	1st to 10th	Day	15% 7% 3 6% 5% 4 5% 6% 5% 6% 37%	1710
	11th to 20th	Day	16% 7% 3 4 6% 4 3 5% 5% 7% 40%	1743
	21st to end	Day	19% 9% 3 7% 4 3 4 5% 4 5% 37%	1570
March	1st to 10th	Day	14% 6% 2 5% 6% 3 4 5% 4 6% 45%	1917
	11th to 20th	Day	16% 7% 3 5% 5% 3 5% 6% 6% 8% 36%	1980
	21st to end	Day	21% 7% 3 6% 5% 3 4 3 5% 7% 38%	2256
April	1st to 10th	Day	16% 6% 3 5% 5% 3 4 4 5% 8% 40%	2160
	11th to 20th	Day	16% 6% 2 5% 4 3 4 4 5% 7% 44%	2134
	21st to end	Day	18% 4 2 5% 4 3 5% 6% 5% 7% 40%	2160
May	1st to 10th	Day	17% 6% 3 6% 5% 3 5% 6% 6% 8% 36%	2319
	11th to 20th	Day	21% 6% 3 4 5% 3 4 5% 6% 6% 37%	2478
	21st to end	Day	14% 7% 2 5% 5% 2 5% 5% 7% 9% 39%	2725
June	1st to 10th	Day	13% 5% 2 5% 5% 3 6% 6% 7% 10% 39%	2520
	11th to 20th	Day	13% 6% 3 5% 5% 3 5% 6% 7% 8% 39%	2520
	21st to end	Day	11% 4 2 5% 5% 4 5% 5% 6% 11% 43%	2520
July	1st to 10th	Day	10% 5% 2 5% 6% 4 5% 6% 7% 11% 39%	2520
	11th to 20th	Day	8% 4 2 5% 5% 4 6% 7% 7% 10% 42%	2520
	21st to end	Day	9% 6% 3 6% 6% 4 7% 6% 6% 9% 38%	2620
August	1st to 10th	Day	11% 5% 2 5% 6% 5% 6% 5% 7% 9% 37%	2327
	11th to 20th	Day	12% 6% 3 5% 6% 4 5% 5% 7% 9% 40%	2188
	21st to end	Day	12% 5% 2 5% 4 3 5% 5% 7% 8% 43%	2376
September	1st to 10th	Day	16% 7% 2 4 5% 3 5% 4 4 6% 44%	2160
	11th to 20th	Day	13% 4 2 4 4 3 4 4 5% 8% 50%	2160
	21st to end	Day	19% 7% 3 5% 4 3 4 4 5% 7% 40%	1922
October	1st to 10th	Day	18% 6% 2 4 4 2 4 4 6% 7% 43%	1800
	11th to 20th	Day	18% 5% 3 5% 4 3 3 4 4 7% 44%	1800
	21st to end	Day	18% 6% 3 4 4 2 3 5% 5% 7% 43%	1976
November	1st to 10th	Day	13% 6% 3 3 4 2 4 3 5% 7% 50%	1671
	11th to 20th	Day	16% 5% 2 4 4 2 5% 4 5% 7% 46%	1701
	21st to end	Day	16% 5% 3 5% 5% 2 5% 5% 5% 7% 43%	1520
December	1st to 10th	Day	19% 9% 3 6% 5% 2 5% 5% 5% 7% 36%	1520
	11th to 20th	Day	20% 6% 2 4 5% 3 4 5% 5% 8% 38%	1906
	21st to end	Day	17% 7% 3 6% 7% 4 6% 5% 6% 6% 33%	2772
January	1st to 10th	Night	15% 7% 3 5% 5% 3 4 4 5% 8% 40%	4429
	11th to 20th	Night	19% 8% 2 5% 5% 3 4 4 5% 6% 40%	4248
	21st to end	Night	23% 8% 3 6% 5% 3 3 3 4 6% 36%	4532
February	1st to 10th	Night	17% 8% 3 4 5% 3 4 4 5% 7% 38%	2470
	11th to 20th	Night	17% 7% 3 6% 5% 2 4 4 5% 6% 40%	2323
	21st to end	Night	18% 8% 3 4 6% 3 4 4 5% 6% 39%	1884
March	1st to 10th	Night	15% 5% 2 4 4 3 4 3 5% 8% 46%	2145
	11th to 20th	Night	17% 7% 3 5% 5% 3 4 5% 4 4 44%	1979
	21st to end	Night	18% 7% 3 5% 5% 2 4 4 5% 7% 41%	2098
April	1st to 10th	Night	18% 6% 3 6% 5% 2 5% 4 6% 8% 38%	1800
	11th to 20th	Night	14% 6% 3 5% 5% 2 4 4 6% 8% 43%	1775
	21st to end	Night	19% 5% 2 5% 5% 2 3 5% 5% 6% 44%	1800
May	1st to 10th	Night	19% 6% 3 6% 5% 3 4 5% 4 8% 38%	1653
	11th to 20th	Night	19% 6% 3 6% 5% 3 4 4 5% 8% 37%	1415
	21st to end	Night	13% 6% 2 6% 5% 3 4 4 5% 11% 41%	1550
June	1st to 10th	Night	15% 5% 2 5% 5% 3 5% 5% 6% 8% 43%	1440
	11th to 20th	Night	13% 4 3 5% 5% 3 4 6% 7% 10% 40%	1440
	21st to end	Night	10% 4 3 4 5% 3 5% 5% 6% 11% 43%	1440
July	1st to 10th	Night	9% 5% 4 7% 7% 4 6% 5% 7% 9% 37%	1440
	11th to 20th	Night	7% 3 2 4 6% 4 6% 6% 7% 11% 46%	1440
	21st to end	Night	10% 4 2 5% 5% 3 6% 6% 6% 11% 41%	1694
August	1st to 10th	Night	10% 5% 2 5% 5% 4 6% 6% 7% 10% 42%	1611
	11th to 20th	Night	11% 6% 2 6% 6% 4 6% 6% 6% 7% 41%	1693
	21st to end	Night	13% 4 2 5% 6% 3 4 6% 6% 9% 43%	1980
September	1st to 10th	Night	14% 6% 2 5% 5% 3 4 4 5% 7% 46%	1800
	11th to 20th	Night	13% 5% 2 3 3 2 4 5% 5% 7% 51%	1800
	21st to end	Night	17% 6% 2 5% 4 3 5% 5% 5% 5% 42%	2034
October	1st to 10th	Night	21% 6% 2 4 5% 3 3 3 4 6% 44%	2160
	11th to 20th	Night	17% 5% 2 5% 5% 3 3 4 5% 6% 47%	2160
	21st to end	Night	18% 6% 2 3 4 2 3 4 5% 7% 46%	2379
November	1st to 10th	Night	11% 5% 2 4 4 3 4 4 5% 6% 53%	2407
	11th to 20th	Night	16% 7% 2 5% 3 3 4 4 5% 6% 46%	2474
	21st to end	Night	14% 5% 2 5% 5% 3 4 4 5% 7% 45%	2660
December	1st to 10th	Night	19% 7% 3 5% 5% 4 5% 5% 5% 7% 37%	2660
	11th to 20th	Night	18% 5% 2 5% 5% 3 4 5% 5% 7% 40%	3288
	21st to end	Night	18% 7% 3 5% 5% 3 5% 6% 6% 8% 34%	4884

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% 5% 14% 25% 11% 3	2518
	11th to 20th	Day	50% 6% 12% 17% 12% 2	2694
	21st to end	Day	52% 6% 11% 21% 8% 1	3124
February	1st to 10th	Day	46% 6% 14% 23% 11% 1	1710
	11th to 20th	Day	45% 5% 11% 24% 14% 2	1752
	21st to end	Day	50% 4 11% 21% 11% 4	1570
March	1st to 10th	Day	40% 6% 12% 26% 14% 2	1920
	11th to 20th	Day	45% 6% 12% 18% 15% 4	1980
	21st to end	Day	48% 5% 9% 19% 17% 3	2256
April	1st to 10th	Day	43% 5% 12% 20% 16% 5%	2160
	11th to 20th	Day	39% 6% 12% 22% 16% 5%	2134
	21st to end	Day	42% 7% 11% 20% 16% 4	2160
May	1st to 10th	Day	45% 8% 10% 20% 15% 3	2319
	11th to 20th	Day	46% 7% 11% 21% 12% 2	2482
	21st to end	Day	40% 9% 15% 22% 12% 2	2725
June	1st to 10th	Day	39% 9% 13% 23% 15% 1	2520
	11th to 20th	Day	40% 9% 13% 24% 11% 3	2520
	21st to end	Day	34% 9% 15% 25% 15% 1	2520
July	1st to 10th	Day	38% 10% 12% 23% 15% 3	2450
	11th to 20th	Day	33% 9% 14% 26% 16% 2	2445
	21st to end	Day	41% 10% 12% 21% 15% 2	2473
August	1st to 10th	Day	40% 9% 13% 23% 15% 1	2314
	11th to 20th	Day	39% 8% 14% 21% 16% 2	2188
	21st to end	Day	38% 8% 12% 24% 16% 3	2376
September	1st to 10th	Day	41% 6% 11% 20% 18% 4	2160
	11th to 20th	Day	32% 6% 11% 26% 22% 4	2160
	21st to end	Day	44% 6% 9% 18% 20% 3	1922
October	1st to 10th	Day	40% 5% 13% 24% 17% 1	1800
	11th to 20th	Day	41% 5% 11% 23% 19% 2	1800
	21st to end	Day	40% 6% 11% 25% 17% 2	1976
November	1st to 10th	Day	35% 3 14% 24% 19% 4	1671
	11th to 20th	Day	39% 5% 12% 23% 19% 2	1701
	21st to end	Day	41% 5% 12% 30% 10% 3	1520
December	1st to 10th	Day	48% 6% 15% 19% 11% 1	1520
	11th to 20th	Day	44% 4 15% 28% 8% 1	1906
	21st to end	Day	49% 7% 15% 20% 9% 1	2772
January	1st to 10th	Night	42% 6% 13% 26% 11% 3	4429
	11th to 20th	Night	44% 4 15% 23% 12% 2	4248
	21st to end	Night	50% 4 10% 26% 9% 1	4532
February	1st to 10th	Night	45% 5% 13% 24% 11% 2	2470
	11th to 20th	Night	45% 4 9% 21% 18% 2	2325
	21st to end	Night	45% 6% 10% 20% 15% 4	1884
March	1st to 10th	Night	37% 6% 12% 26% 17% 3	2155
	11th to 20th	Night	43% 5% 11% 21% 16% 4	1980
	21st to end	Night	43% 5% 10% 20% 18% 4	2098
April	1st to 10th	Night	44% 5% 11% 20% 16% 4	1800
	11th to 20th	Night	39% 6% 12% 20% 20% 3	1775
	21st to end	Night	41% 6% 10% 21% 17% 6%	1800
May	1st to 10th	Night	44% 8% 11% 19% 15% 4	1653
	11th to 20th	Night	46% 7% 12% 15% 18% 2	1416
	21st to end	Night	40% 9% 14% 20% 15% 2	1551
June	1st to 10th	Night	39% 8% 10% 22% 20% 1	1440
	11th to 20th	Night	37% 10% 14% 23% 15% 2	1440
	21st to end	Night	34% 8% 15% 26% 16% 2	1440
July	1st to 10th	Night	42% 10% 13% 18% 13% 3	1400
	11th to 20th	Night	32% 9% 15% 25% 16% 3	1392
	21st to end	Night	34% 11% 16% 21% 16% 2	1600
August	1st to 10th	Night	35% 10% 15% 25% 15% 1	1600
	11th to 20th	Night	40% 9% 14% 18% 16% 2	1693
	21st to end	Night	36% 8% 14% 21% 18% 3	1980
September	1st to 10th	Night	39% 6% 11% 22% 19% 4	1800
	11th to 20th	Night	32% 6% 9% 24% 25% 4	1800
	21st to end	Night	42% 6% 9% 19% 21% 3	2034
October	1st to 10th	Night	43% 4 11% 23% 16% 2	2160
	11th to 20th	Night	37% 6% 10% 28% 17% 2	2160
	21st to end	Night	38% 5% 10% 27% 18% 2	2379
November	1st to 10th	Night	32% 5% 12% 26% 20% 4	2407
	11th to 20th	Night	39% 4 10% 24% 18% 4	2474
	21st to end	Night	38% 6% 13% 28% 15% 2	2660
December	1st to 10th	Night	47% 6% 12% 21% 13% 1	2660
	11th to 20th	Night	43% 5% 14% 22% 14% 3	3288
	21st to end	Night	45% 8% 15% 22% 9%	4884

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% 24% 29% 16% 3 1	180
	11th to 20th	Day	28% 29% 29% 12% 1	231
	21st to end	Day	24% 30% 30% 14% 2 1	297
February	1st to 10th	Day	26% 24% 33% 14% 3	270
	11th to 20th	Day	30% 23% 37% 9% 1	350
	21st to end	Day	34% 16% 31% 17% 2	382
March	1st to 10th	Day	23% 22% 32% 19% 3	440
	11th to 20th	Day	25% 26% 32% 13% 4 1	420
	21st to end	Day	26% 21% 30% 16% 5% 2	462
April	1st to 10th	Day	23% 22% 30% 17% 6% 1	420
	11th to 20th	Day	23% 19% 26% 21% 8% 3	412
	21st to end	Day	27% 15% 32% 18% 5% 2	420
May	1st to 10th	Day	25% 19% 26% 20% 7% 3	423
	11th to 20th	Day	20% 15% 33% 19% 10% 3	447
	21st to end	Day	19% 7% 26% 24% 19% 5%	485
June	1st to 10th	Day	16% 12% 28% 23% 16% 4	450
	11th to 20th	Day	19% 11% 25% 26% 16% 3	450
	21st to end	Day	14% 9% 26% 31% 14% 6%	450
July	1st to 10th	Day	13% 4 20% 28% 25% 10%	445
	11th to 20th	Day	7% 4 19% 35% 27% 8%	444
	21st to end	Day	13% 5% 25% 32% 19% 6%	488
August	1st to 10th	Day	13% 4 22% 27% 24% 9%	446
	11th to 20th	Day	12% 7% 19% 31% 20% 11%	439
	21st to end	Day	13% 4 20% 33% 19% 11%	495
September	1st to 10th	Day	21% 7% 18% 23% 20% 10%	450
	11th to 20th	Day	14% 4 22% 28% 20% 12%	450
	21st to end	Day	22% 12% 22% 23% 15% 6%	450
October	1st to 10th	Day	21% 7% 26% 23% 18% 5%	450
	11th to 20th	Day	20% 13% 28% 24% 14% 2	450
	21st to end	Day	19% 15% 34% 22% 8% 2	493
November	1st to 10th	Day	16% 12% 28% 28% 13% 3	365
	11th to 20th	Day	20% 19% 30% 22% 8% 1	361
	21st to end	Day	22% 20% 36% 14% 8% 1	180
December	1st to 10th	Day	26% 22% 34% 12% 4 2	180
	11th to 20th	Day	28% 21% 31% 16% 3 1	180
	21st to end	Day	24% 22% 28% 18% 7% 1	198
January	1st to 10th	Night	18% 18% 42% 19% 3	760
	11th to 20th	Night	25% 16% 33% 22% 4	760
	21st to end	Night	18% 16% 42% 21% 2	836
February	1st to 10th	Night	21% 18% 35% 24% 2	760
	11th to 20th	Night	23% 21% 38% 16% 1	743
	21st to end	Night	23% 21% 37% 17% 3	628
March	1st to 10th	Night	19% 16% 39% 22% 4	743
	11th to 20th	Night	23% 17% 34% 20% 6% 1	720
	21st to end	Night	20% 13% 39% 22% 6% 1	792
April	1st to 10th	Night	22% 18% 35% 20% 5%	720
	11th to 20th	Night	18% 13% 34% 27% 8%	711
	21st to end	Night	22% 13% 33% 26% 7%	720
May	1st to 10th	Night	22% 9% 29% 30% 9%	573
	11th to 20th	Night	20% 8% 31% 32% 9%	354
	21st to end	Night	15% 5% 24% 39% 15% 2	389
June	1st to 10th	Night	17% 3 25% 38% 17%	360
	11th to 20th	Night	14% 4 26% 40% 16%	360
	21st to end	Night	12% 2 22% 51% 13% 1	360
July	1st to 10th	Night	11% 2 19% 43% 22% 2	350
	11th to 20th	Night	7% 2 17% 46% 26% 2	348
	21st to end	Night	11% 3 19% 41% 25% 1	514
August	1st to 10th	Night	12% 1 12% 46% 26% 2	537
	11th to 20th	Night	14% 4 12% 39% 28% 3	629
	21st to end	Night	15% 4 16% 37% 25% 3	792
September	1st to 10th	Night	16% 4 22% 33% 22% 4	720
	11th to 20th	Night	14% 3 19% 34% 25% 4	720
	21st to end	Night	19% 5% 21% 34% 20% 2	720
October	1st to 10th	Night	22% 6% 22% 30% 16% 4	720
	11th to 20th	Night	19% 10% 27% 32% 13%	720
	21st to end	Night	20% 11% 31% 27% 10%	792
November	1st to 10th	Night	14% 9% 34% 31% 12% 1	740
	11th to 20th	Night	18% 16% 29% 27% 8% 1	760
	21st to end	Night	16% 16% 35% 25% 7%	760
December	1st to 10th	Night	24% 16% 34% 20% 6%	760
	11th to 20th	Night	18% 15% 38% 24% 4	760
	21st to end	Night	21% 13% 35% 29% 1	836

Page generated at 2024-03-03 06:29:01. Version ac07

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