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 2026-09-29.

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	16% 6% 2 6% 4 4 5% 4 6% 8% 40%	149407
	Night	16% 6% 2 6% 4 4 4 4 5% 7% 41%	141970
Transparency	Day	41% 6% 12% 23% 15% 2	152985
	Night	41% 6% 12% 23% 16% 3	146479
Seeing	Day	20% 14% 27% 23% 13% 4	17373
	Night	18% 11% 30% 29% 11% 1	26672

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	14% 6% 2 8% 5% 5% 5% 3 5% 6% 41%	4661
	11th to 20th	Day	14% 9% 3 9% 5% 4 4 3 5% 5% 39%	4989
	21st to end	Day	15% 6% 3 7% 5% 5% 6% 4 6% 7% 37%	5780
February	1st to 10th	Day	14% 8% 3 7% 4 5% 5% 5% 6% 6% 37%	1890
	11th to 20th	Day	16% 9% 3 6% 5% 4 3 4 5% 6% 38%	1932
	21st to end	Day	18% 9% 3 7% 4 4 4 4 4 5% 38%	1730
March	1st to 10th	Day	20% 5% 1 4 4 4 4 4 5% 6% 43%	4762
	11th to 20th	Day	12% 6% 2 6% 4 5% 5% 4 6% 7% 43%	5090
	21st to end	Day	17% 7% 2 5% 4 4 4 3 5% 6% 43%	5807
April	1st to 10th	Day	17% 6% 2 6% 4 4 4 4 5% 8% 39%	2520
	11th to 20th	Day	15% 7% 1 5% 4 4 4 4 6% 7% 43%	2494
	21st to end	Day	17% 5% 2 6% 3 5% 4 4 5% 7% 41%	2520
May	1st to 10th	Day	23% 5% 2 6% 4 4 4 4 6% 8% 34%	7591
	11th to 20th	Day	20% 6% 2 5% 4 4 4 4 6% 8% 37%	8221
	21st to end	Day	24% 6% 2 5% 3 4 4 3 5% 7% 37%	9060
June	1st to 10th	Day	12% 5% 1 5% 5% 5% 5% 4 7% 9% 41%	2940
	11th to 20th	Day	13% 6% 2 6% 4 5% 5% 5% 7% 8% 39%	2940
	21st to end	Day	11% 5% 2 6% 5% 5% 4 4 6% 10% 43%	2940
July	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 4 6% 9% 40%	8280
	11th to 20th	Day	10% 5% 3 7% 5% 5% 6% 5% 7% 11% 36%	8280
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 6% 9% 41%	8578
August	1st to 10th	Day	17% 5% 3 8% 6% 6% 6% 5% 7% 8% 29%	6014
	11th to 20th	Day	15% 4 2 6% 4 4 5% 4 6% 9% 40%	5648
	21st to end	Day	11% 5% 2 6% 3 4 5% 3 6% 8% 47%	6080
September	1st to 10th	Day	15% 6% 2 4 4 4 4 3 4 7% 46%	2520
	11th to 20th	Day	13% 5% 2 5% 4 4 3 4 5% 7% 50%	2520
	21st to end	Day	22% 8% 3 6% 4 4 4 3 5% 6% 36%	2221
October	1st to 10th	Day	18% 6% 2 5% 3 3 4 3 6% 6% 46%	2000
	11th to 20th	Day	16% 5% 2 6% 4 4 4 2 5% 7% 45%	2000
	21st to end	Day	16% 5% 2 5% 4 3 3 4 5% 7% 45%	2195
November	1st to 10th	Day	12% 7% 2 4 3 3 3 3 5% 8% 51%	1851
	11th to 20th	Day	15% 6% 2 5% 4 4 4 4 5% 7% 45%	1879
	21st to end	Day	15% 7% 2 6% 4 4 4 3 5% 7% 42%	1680
December	1st to 10th	Day	15% 8% 2 6% 4 4 4 4 5% 6% 43%	2680
	11th to 20th	Day	21% 9% 2 4 3 4 3 3 5% 7% 39%	3066
	21st to end	Day	17% 7% 2 7% 5% 5% 5% 4 6% 7% 35%	4048
January	1st to 10th	Night	12% 7% 3 7% 5% 5% 4 4 6% 8% 40%	8234
	11th to 20th	Night	14% 7% 2 6% 4 4 4 3 5% 6% 45%	7878
	21st to end	Night	15% 7% 3 6% 3 3 3 3 5% 7% 45%	8401
February	1st to 10th	Night	16% 8% 2 5% 5% 4 5% 4 6% 7% 38%	2730
	11th to 20th	Night	18% 8% 3 7% 4 4 4 3 5% 6% 39%	2573
	21st to end	Night	16% 8% 3 5% 5% 5% 4 3 6% 5% 40%	2076
March	1st to 10th	Night	18% 8% 2 6% 4 3 3 3 4 6% 44%	5282
	11th to 20th	Night	11% 6% 2 5% 4 4 4 3 5% 6% 50%	5089
	21st to end	Night	15% 7% 2 6% 4 4 4 3 5% 6% 44%	5365
April	1st to 10th	Night	19% 7% 2 7% 5% 3 4 3 6% 7% 37%	2100
	11th to 20th	Night	14% 7% 3 6% 4 3 4 3 6% 7% 42%	2075
	21st to end	Night	18% 5% 2 5% 4 3 4 4 5% 6% 44%	2100
May	1st to 10th	Night	23% 6% 2 7% 5% 4 4 4 5% 7% 33%	5334
	11th to 20th	Night	21% 7% 3 6% 4 3 3 4 5% 8% 36%	4639
	21st to end	Night	25% 6% 2 6% 4 4 3 3 4 7% 35%	5114
June	1st to 10th	Night	14% 5% 2 6% 4 4 4 4 6% 8% 44%	1680
	11th to 20th	Night	13% 5% 2 6% 4 4 4 5% 7% 10% 40%	1680
	21st to end	Night	11% 5% 2 6% 3 5% 5% 5% 6% 11% 42%	1680
July	1st to 10th	Night	12% 5% 3 7% 5% 5% 5% 4 6% 9% 39%	4680
	11th to 20th	Night	11% 5% 3 8% 6% 6% 6% 5% 7% 11% 34%	4680
	21st to end	Night	13% 5% 2 6% 5% 4 5% 4 6% 8% 43%	5495
August	1st to 10th	Night	19% 6% 2 8% 5% 5% 6% 4 6% 9% 31%	4135
	11th to 20th	Night	15% 6% 2 6% 5% 5% 5% 4 6% 7% 39%	4350
	21st to end	Night	13% 5% 2 6% 4 4 4 4 5% 8% 45%	5045
September	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 47%	2100
	11th to 20th	Night	13% 5% 2 4 2 3 3 4 6% 7% 50%	2100
	21st to end	Night	20% 7% 2 6% 4 5% 4 4 5% 6% 37%	2351
October	1st to 10th	Night	20% 6% 2 5% 4 3 2 2 4 6% 46%	2400
	11th to 20th	Night	16% 5% 2 6% 3 3 3 3 5% 5% 49%	2400
	21st to end	Night	17% 6% 2 4 3 3 3 3 5% 7% 48%	2644
November	1st to 10th	Night	11% 5% 1 4 3 3 4 3 5% 6% 53%	2667
	11th to 20th	Night	15% 7% 2 5% 3 4 3 3 5% 6% 46%	2735
	21st to end	Night	14% 6% 2 5% 5% 4 4 4 5% 7% 44%	2940
December	1st to 10th	Night	13% 7% 3 7% 4 4 4 3 5% 7% 43%	4720
	11th to 20th	Night	22% 6% 2 5% 3 3 4 4 4 6% 40%	5348
	21st to end	Night	19% 8% 3 6% 4 4 4 4 5% 6% 36%	7150

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	44% 4 11% 25% 14% 2	4662
	11th to 20th	Day	45% 4 9% 19% 16% 6%	5022
	21st to end	Day	46% 5% 12% 23% 13% 1	5780
February	1st to 10th	Day	45% 6% 13% 24% 11% 2	1890
	11th to 20th	Day	47% 5% 11% 23% 13% 2	1941
	21st to end	Day	48% 4 11% 23% 11% 3	1730
March	1st to 10th	Day	40% 5% 10% 23% 15% 6%	4765
	11th to 20th	Day	39% 5% 13% 26% 13% 5%	5090
	21st to end	Day	43% 5% 9% 18% 21% 4	5807
April	1st to 10th	Day	44% 5% 11% 20% 16% 5%	2520
	11th to 20th	Day	39% 6% 14% 22% 15% 4	2494
	21st to end	Day	42% 6% 10% 22% 16% 4	2520
May	1st to 10th	Day	47% 7% 11% 21% 13% 1	7600
	11th to 20th	Day	44% 7% 11% 25% 13% 1	8225
	21st to end	Day	46% 6% 10% 22% 14% 1	9061
June	1st to 10th	Day	38% 8% 13% 23% 17% 1	2940
	11th to 20th	Day	39% 8% 13% 25% 12% 3	2940
	21st to end	Day	35% 8% 15% 25% 15% 1	2940
July	1st to 10th	Day	40% 9% 13% 21% 16% 2	8210
	11th to 20th	Day	40% 8% 14% 26% 11% 1	8205
	21st to end	Day	38% 7% 10% 23% 21% 1	8389
August	1st to 10th	Day	50% 9% 12% 19% 9%	6001
	11th to 20th	Day	38% 7% 14% 29% 12% 1	5687
	21st to end	Day	34% 7% 12% 28% 18% 2	6080
September	1st to 10th	Day	39% 6% 12% 21% 19% 4	2520
	11th to 20th	Day	33% 5% 11% 26% 22% 4	2520
	21st to end	Day	49% 5% 9% 16% 19% 2	2221
October	1st to 10th	Day	36% 4 8% 20% 27% 5%	3260
	11th to 20th	Day	28% 4 12% 27% 22% 7%	3240
	21st to end	Day	25% 4 12% 27% 28% 3	3521
November	1st to 10th	Day	34% 3 14% 24% 20% 4	1851
	11th to 20th	Day	38% 5% 12% 24% 19% 3	1879
	21st to end	Day	41% 5% 12% 29% 10% 2	1680
December	1st to 10th	Day	42% 5% 16% 24% 11% 2	2680
	11th to 20th	Day	45% 4 13% 29% 8% 1	3066
	21st to end	Day	45% 6% 15% 20% 13% 1	4048
January	1st to 10th	Night	41% 5% 13% 24% 14% 3	8234
	11th to 20th	Night	39% 4 12% 21% 18% 6%	7920
	21st to end	Night	39% 4 10% 28% 18% 2	8401
February	1st to 10th	Night	44% 5% 13% 24% 12% 2	2730
	11th to 20th	Night	46% 4 10% 21% 18% 2	2575
	21st to end	Night	45% 6% 10% 21% 15% 4	2076
March	1st to 10th	Night	42% 5% 9% 23% 13% 8%	5292
	11th to 20th	Night	33% 5% 16% 27% 13% 5%	5090
	21st to end	Night	41% 4 8% 18% 25% 3	5365
April	1st to 10th	Night	45% 5% 10% 20% 16% 4	2100
	11th to 20th	Night	40% 6% 12% 20% 20% 3	2075
	21st to end	Night	40% 6% 10% 22% 17% 5%	2100
May	1st to 10th	Night	49% 6% 11% 19% 13% 2	5341
	11th to 20th	Night	46% 7% 12% 24% 10% 1	4640
	21st to end	Night	50% 6% 9% 20% 13% 2	5115
June	1st to 10th	Night	38% 8% 9% 23% 21% 1	1680
	11th to 20th	Night	37% 10% 13% 24% 15% 2	1680
	21st to end	Night	35% 8% 14% 25% 16% 2	1680
July	1st to 10th	Night	42% 8% 13% 19% 15% 3	4640
	11th to 20th	Night	43% 8% 15% 23% 11% 1	4632
	21st to end	Night	37% 8% 13% 22% 18% 1	5369
August	1st to 10th	Night	49% 8% 14% 18% 10%	4124
	11th to 20th	Night	42% 7% 14% 25% 11% 1	4377
	21st to end	Night	37% 6% 11% 29% 16% 1	5045
September	1st to 10th	Night	38% 6% 11% 22% 20% 4	2100
	11th to 20th	Night	33% 6% 9% 25% 24% 4	2100
	21st to end	Night	47% 6% 8% 17% 19% 2	2351
October	1st to 10th	Night	43% 4 9% 20% 22% 2	3920
	11th to 20th	Night	27% 5% 10% 28% 26% 4	3899
	21st to end	Night	26% 4 11% 32% 25% 3	4268
November	1st to 10th	Night	32% 5% 12% 26% 21% 4	2667
	11th to 20th	Night	39% 4 9% 24% 19% 5%	2735
	21st to end	Night	39% 6% 13% 27% 15% 1	2940
December	1st to 10th	Night	40% 5% 13% 29% 12% 1	4720
	11th to 20th	Night	45% 4 13% 24% 12% 2	5348
	21st to end	Night	47% 7% 11% 19% 16% 1	7150

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	25% 25% 31% 15% 2 1	220
	11th to 20th	Day	27% 30% 30% 12% 1	283
	21st to end	Day	21% 29% 33% 13% 2 1	363
February	1st to 10th	Day	24% 24% 33% 15% 3 1	330
	11th to 20th	Day	31% 21% 35% 11% 1	419
	21st to end	Day	31% 16% 34% 17% 2	446
March	1st to 10th	Day	24% 21% 31% 20% 4	540
	11th to 20th	Day	25% 25% 30% 14% 5% 1	540
	21st to end	Day	24% 21% 34% 15% 5% 2	594
April	1st to 10th	Day	26% 20% 30% 17% 7% 1	540
	11th to 20th	Day	22% 19% 29% 20% 8% 2	532
	21st to end	Day	26% 14% 30% 21% 7% 2	540
May	1st to 10th	Day	24% 18% 27% 21% 7% 2	543
	11th to 20th	Day	19% 14% 31% 23% 11% 3	567
	21st to end	Day	22% 9% 26% 23% 17% 4	617
June	1st to 10th	Day	15% 13% 27% 22% 19% 5%	570
	11th to 20th	Day	19% 10% 25% 27% 16% 4	570
	21st to end	Day	13% 8% 25% 29% 18% 6%	570
July	1st to 10th	Day	13% 4 18% 27% 27% 10%	565
	11th to 20th	Day	7% 5% 19% 35% 26% 9%	564
	21st to end	Day	13% 5% 23% 32% 22% 6%	620
August	1st to 10th	Day	14% 4 21% 27% 24% 10%	566
	11th to 20th	Day	13% 6% 19% 30% 21% 10%	559
	21st to end	Day	12% 4 20% 33% 20% 12%	627
September	1st to 10th	Day	19% 6% 19% 26% 20% 11%	570
	11th to 20th	Day	13% 3 20% 28% 23% 12%	570
	21st to end	Day	25% 11% 22% 23% 14% 5%	562
October	1st to 10th	Day	19% 8% 25% 23% 17% 8%	530
	11th to 20th	Day	18% 15% 28% 24% 14% 3	530
	21st to end	Day	17% 14% 34% 22% 10% 3	580
November	1st to 10th	Day	14% 13% 30% 29% 12% 2	425
	11th to 20th	Day	19% 19% 31% 23% 8%	419
	21st to end	Day	24% 21% 35% 13% 7%	220
December	1st to 10th	Day	25% 20% 35% 14% 5% 1	220
	11th to 20th	Day	27% 20% 33% 17% 3	220
	21st to end	Day	24% 21% 29% 18% 7%	242
January	1st to 10th	Night	17% 19% 42% 20% 3	840
	11th to 20th	Night	23% 16% 35% 22% 3	840
	21st to end	Night	18% 16% 43% 21% 2	924
February	1st to 10th	Night	21% 17% 36% 24% 2	840
	11th to 20th	Night	23% 21% 37% 18% 1	823
	21st to end	Night	21% 20% 38% 18% 3	692
March	1st to 10th	Night	20% 17% 38% 21% 4	840
	11th to 20th	Night	22% 18% 34% 21% 5%	840
	21st to end	Night	20% 14% 39% 22% 5%	924
April	1st to 10th	Night	23% 17% 36% 20% 5%	840
	11th to 20th	Night	18% 14% 34% 27% 7%	831
	21st to end	Night	20% 12% 32% 28% 7%	840
May	1st to 10th	Night	23% 10% 29% 30% 8%	666
	11th to 20th	Night	19% 8% 31% 33% 9%	414
	21st to end	Night	17% 5% 25% 39% 14% 2	455
June	1st to 10th	Night	15% 4 24% 39% 18%	420
	11th to 20th	Night	14% 4 26% 41% 14%	420
	21st to end	Night	13% 2 20% 50% 15%	420
July	1st to 10th	Night	11% 2 18% 43% 23% 2	410
	11th to 20th	Night	7% 2 15% 48% 26% 2	408
	21st to end	Night	10% 3 18% 42% 26% 2	601
August	1st to 10th	Night	13% 2 11% 44% 28% 2	627
	11th to 20th	Night	14% 5% 12% 39% 28% 2	736
	21st to end	Night	15% 3 16% 39% 25% 2	924
September	1st to 10th	Night	15% 4 22% 34% 22% 3	840
	11th to 20th	Night	14% 3 17% 37% 25% 4	840
	21st to end	Night	22% 5% 20% 32% 19% 2	833
October	1st to 10th	Night	21% 6% 21% 30% 18% 4	800
	11th to 20th	Night	18% 9% 28% 32% 13% 1	800
	21st to end	Night	19% 10% 30% 30% 10%	880
November	1st to 10th	Night	13% 9% 33% 32% 12% 1	820
	11th to 20th	Night	18% 16% 30% 28% 7% 1	840
	21st to end	Night	16% 15% 36% 25% 7%	840
December	1st to 10th	Night	22% 15% 35% 21% 6%	840
	11th to 20th	Night	19% 14% 37% 25% 4	840
	21st to end	Night	22% 13% 35% 29% 2	924

Page generated at 2026-09-26 04:18:42. Version ac07

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