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 2024-11-02.

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 4 4 6% 7% 40%	101319
	Night	16% 7% 2 6% 4 4 4 4 5% 7% 41%	97629
Transparency	Day	42% 7% 12% 23% 14% 2	101082
	Night	42% 6% 12% 23% 15% 2	97485
Seeing	Day	20% 14% 27% 23% 13% 4	14915
	Night	18% 11% 30% 29% 11% 1	24249

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% 8% 2 6% 4 4 5% 3 5% 6% 43%	2517
	11th to 20th	Day	15% 11% 4 10% 5% 4 4 4 6% 6% 32%	2694
	21st to end	Day	20% 10% 4 8% 5% 4 4 3 4 5% 32%	3124
February	1st to 10th	Day	15% 8% 3 7% 4 5% 5% 5% 6% 6% 37%	1710
	11th to 20th	Day	15% 8% 3 6% 5% 4 3 4 5% 7% 40%	1743
	21st to end	Day	19% 9% 3 7% 4 4 4 4 4 5% 37%	1570
March	1st to 10th	Day	24% 6% 2 5% 4 4 4 4 5% 7% 36%	3242
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 4 6% 8% 43%	3480
	21st to end	Day	21% 8% 2 5% 4 3 3 2 4 5% 43%	3962
April	1st to 10th	Day	17% 6% 2 6% 5% 4 4 4 5% 8% 39%	2280
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 5% 6% 43%	2254
	21st to end	Day	17% 5% 2 6% 3 5% 4 5% 5% 7% 40%	2280
May	1st to 10th	Day	28% 6% 2 6% 4 4 4 4 5% 7% 30%	4087
	11th to 20th	Day	24% 9% 3 6% 5% 4 4 4 6% 6% 29%	4398
	21st to end	Day	12% 5% 1 5% 4 4 4 4 6% 9% 45%	4837
June	1st to 10th	Day	13% 5% 1 5% 5% 5% 5% 4 7% 10% 40%	2660
	11th to 20th	Day	12% 7% 2 6% 4 5% 5% 5% 7% 8% 39%	2660
	21st to end	Day	11% 4 2 5% 5% 5% 5% 4 6% 10% 43%	2660
July	1st to 10th	Day	7% 4 2 6% 6% 6% 6% 5% 8% 11% 38%	4440
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 9% 40%	4440
	21st to end	Day	11% 7% 3 8% 6% 6% 6% 5% 6% 8% 35%	4595
August	1st to 10th	Day	20% 5% 2 6% 5% 5% 5% 4 6% 8% 33%	4104
	11th to 20th	Day	15% 4 2 6% 4 4 5% 4 7% 8% 42%	3831
	21st to end	Day	13% 5% 2 6% 3 3 4 3 5% 7% 49%	4180
September	1st to 10th	Day	16% 7% 2 5% 4 4 4 3 4 6% 45%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 3 3 5% 8% 50%	2280
	21st to end	Day	21% 7% 3 6% 4 4 4 3 5% 6% 38%	2027
October	1st to 10th	Day	18% 6% 2 5% 3 3 4 3 6% 6% 44%	1900
	11th to 20th	Day	17% 5% 2 5% 4 4 4 2 4 7% 46%	1900
	21st to end	Day	17% 6% 2 5% 4 3 3 4 5% 7% 44%	2085
November	1st to 10th	Day	13% 7% 3 4 3 3 3 3 5% 7% 50%	1680
	11th to 20th	Day	16% 6% 2 5% 4 4 4 3 5% 7% 46%	1701
	21st to end	Day	15% 6% 2 6% 4 4 4 4 5% 7% 43%	1520
December	1st to 10th	Day	19% 9% 2 7% 4 4 4 4 5% 6% 36%	1520
	11th to 20th	Day	20% 7% 2 5% 4 5% 4 4 6% 8% 38%	1906
	21st to end	Day	17% 7% 3 8% 6% 5% 5% 4 6% 6% 33%	2772
January	1st to 10th	Night	15% 7% 3 6% 5% 4 4 4 6% 7% 40%	4429
	11th to 20th	Night	19% 8% 2 6% 4 4 4 3 5% 6% 40%	4248
	21st to end	Night	23% 9% 3 7% 4 4 3 3 4 6% 36%	4532
February	1st to 10th	Night	17% 8% 2 5% 5% 4 5% 3 5% 7% 38%	2470
	11th to 20th	Night	17% 8% 3 7% 4 3 4 3 5% 5% 40%	2323
	21st to end	Night	18% 8% 3 5% 5% 4 4 3 6% 5% 39%	1884
March	1st to 10th	Night	22% 10% 3 6% 4 3 3 2 4 6% 38%	3582
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 5% 6% 49%	3479
	21st to end	Night	16% 8% 2 6% 4 3 3 3 4 5% 46%	3668
April	1st to 10th	Night	18% 7% 2 7% 5% 3 5% 3 6% 8% 37%	1900
	11th to 20th	Night	15% 7% 3 6% 4 3 4 3 6% 7% 42%	1875
	21st to end	Night	19% 5% 2 5% 4 3 4 4 5% 6% 44%	1900
May	1st to 10th	Night	26% 7% 2 7% 4 3 4 3 5% 8% 31%	2880
	11th to 20th	Night	24% 10% 3 7% 4 4 3 3 5% 7% 29%	2495
	21st to end	Night	12% 6% 2 6% 5% 4 4 3 5% 11% 42%	2738
June	1st to 10th	Night	14% 5% 2 6% 4 4 4 4 6% 8% 43%	1520
	11th to 20th	Night	12% 5% 2 6% 4 4 4 5% 7% 10% 41%	1520
	21st to end	Night	10% 5% 2 6% 3 5% 5% 5% 7% 11% 42%	1520
July	1st to 10th	Night	7% 5% 3 7% 6% 6% 5% 5% 7% 9% 41%	2520
	11th to 20th	Night	9% 4 2 7% 6% 6% 6% 4 8% 10% 38%	2520
	21st to end	Night	16% 6% 2 6% 4 4 5% 4 6% 8% 38%	2954
August	1st to 10th	Night	21% 5% 2 6% 4 4 5% 4 6% 8% 34%	2825
	11th to 20th	Night	13% 7% 2 6% 5% 5% 4 4 5% 7% 42%	2964
	21st to end	Night	14% 4 2 5% 4 3 4 4 5% 8% 46%	3476
September	1st to 10th	Night	13% 7% 2 6% 3 4 4 3 5% 6% 47%	1900
	11th to 20th	Night	13% 5% 2 4 2 3 3 4 6% 7% 51%	1900
	21st to end	Night	19% 7% 2 6% 4 4 4 4 5% 5% 40%	2148
October	1st to 10th	Night	20% 7% 2 5% 4 4 2 2 3 6% 45%	2280
	11th to 20th	Night	16% 5% 1 6% 3 3 3 3 5% 6% 49%	2280
	21st to end	Night	17% 6% 2 4 3 3 3 3 5% 7% 47%	2512
November	1st to 10th	Night	11% 5% 1 5% 4 4 4 3 5% 6% 52%	2421
	11th to 20th	Night	15% 7% 2 5% 3 4 3 3 5% 6% 46%	2474
	21st to end	Night	14% 6% 2 5% 5% 4 4 4 5% 7% 45%	2660
December	1st to 10th	Night	19% 7% 2 6% 4 5% 5% 4 5% 6% 37%	2660
	11th to 20th	Night	18% 6% 2 6% 4 3 4 5% 5% 7% 40%	3288
	21st to end	Night	18% 7% 3 6% 4 4 5% 5% 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	47% 5% 11% 26% 10% 2	3245
	11th to 20th	Day	36% 6% 13% 26% 16% 3	3480
	21st to end	Day	45% 4 9% 20% 19% 3	3962
April	1st to 10th	Day	43% 5% 12% 20% 16% 5%	2280
	11th to 20th	Day	39% 7% 12% 22% 16% 5%	2254
	21st to end	Day	42% 7% 11% 21% 16% 4	2280
May	1st to 10th	Day	52% 7% 9% 20% 10% 2	4099
	11th to 20th	Day	53% 8% 12% 18% 7% 1	4402
	21st to end	Day	34% 8% 14% 26% 16% 2	4837
June	1st to 10th	Day	38% 9% 13% 23% 15% 1	2660
	11th to 20th	Day	39% 9% 13% 25% 11% 3	2660
	21st to end	Day	34% 9% 15% 26% 15% 1	2660
July	1st to 10th	Day	37% 11% 15% 21% 14% 3	4370
	11th to 20th	Day	37% 8% 16% 24% 14% 1	4365
	21st to end	Day	45% 8% 11% 18% 17% 1	4448
August	1st to 10th	Day	48% 8% 11% 23% 10%	4091
	11th to 20th	Day	38% 6% 11% 29% 15% 1	3870
	21st to end	Day	34% 6% 10% 28% 20% 2	4180
September	1st to 10th	Day	40% 6% 11% 20% 19% 4	2280
	11th to 20th	Day	32% 6% 11% 25% 23% 4	2280
	21st to end	Day	47% 5% 8% 17% 19% 3	2027
October	1st to 10th	Day	40% 5% 12% 23% 18% 2	1900
	11th to 20th	Day	39% 5% 11% 24% 19% 3	1900
	21st to end	Day	38% 6% 11% 25% 19% 2	2085
November	1st to 10th	Day	35% 3 14% 24% 19% 5%	1680
	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	48% 6% 9% 23% 13% 2	3592
	11th to 20th	Night	33% 6% 15% 28% 15% 2	3480
	21st to end	Night	41% 5% 8% 19% 23% 4	3668
April	1st to 10th	Night	44% 5% 10% 21% 16% 4	1900
	11th to 20th	Night	40% 6% 11% 20% 20% 3	1875
	21st to end	Night	40% 6% 10% 22% 17% 5%	1900
May	1st to 10th	Night	51% 7% 9% 19% 11% 2	2887
	11th to 20th	Night	53% 9% 13% 13% 10% 1	2496
	21st to end	Night	37% 8% 14% 23% 15% 3	2739
June	1st to 10th	Night	38% 8% 10% 22% 20% 1	1520
	11th to 20th	Night	35% 10% 14% 25% 15% 2	1520
	21st to end	Night	34% 8% 15% 25% 16% 2	1520
July	1st to 10th	Night	38% 10% 16% 18% 14% 5%	2480
	11th to 20th	Night	38% 10% 16% 22% 13% 1	2472
	21st to end	Night	41% 9% 13% 18% 18% 1	2860
August	1st to 10th	Night	46% 8% 17% 20% 9%	2814
	11th to 20th	Night	41% 6% 12% 25% 15% 1	2991
	21st to end	Night	34% 6% 11% 29% 18% 1	3476
September	1st to 10th	Night	38% 6% 11% 21% 20% 4	1900
	11th to 20th	Night	32% 6% 9% 25% 25% 4	1900
	21st to end	Night	45% 6% 8% 18% 20% 3	2148
October	1st to 10th	Night	43% 4 11% 23% 17% 2	2280
	11th to 20th	Night	36% 6% 10% 28% 18% 3	2280
	21st to end	Night	36% 5% 10% 28% 19% 2	2512
November	1st to 10th	Night	33% 5% 12% 26% 20% 4	2421
	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	24% 22% 32% 19% 3	460
	11th to 20th	Day	25% 26% 31% 13% 4 1	460
	21st to end	Day	26% 20% 32% 15% 5% 2	506
April	1st to 10th	Day	25% 21% 29% 17% 7% 1	460
	11th to 20th	Day	23% 19% 28% 19% 8% 3	452
	21st to end	Day	27% 15% 31% 20% 5% 2	460
May	1st to 10th	Day	26% 19% 25% 20% 7% 3	463
	11th to 20th	Day	20% 15% 32% 20% 11% 3	487
	21st to end	Day	18% 7% 27% 24% 19% 5%	529
June	1st to 10th	Day	16% 13% 28% 22% 17% 4	490
	11th to 20th	Day	17% 10% 24% 27% 17% 4	490
	21st to end	Day	13% 9% 26% 31% 15% 6%	490
July	1st to 10th	Day	12% 4 20% 28% 26% 9%	485
	11th to 20th	Day	6% 4 19% 36% 27% 7%	484
	21st to end	Day	13% 5% 25% 33% 19% 5%	532
August	1st to 10th	Day	14% 4 22% 27% 23% 9%	486
	11th to 20th	Day	13% 6% 20% 30% 20% 11%	479
	21st to end	Day	13% 4 19% 32% 20% 12%	539
September	1st to 10th	Day	20% 7% 19% 23% 20% 11%	490
	11th to 20th	Day	13% 4 21% 28% 21% 13%	490
	21st to end	Day	25% 12% 21% 22% 14% 6%	490
October	1st to 10th	Day	21% 8% 26% 23% 17% 6%	490
	11th to 20th	Day	18% 13% 27% 24% 14% 3	490
	21st to end	Day	17% 14% 33% 22% 11% 3	536
November	1st to 10th	Day	16% 13% 28% 27% 13% 3	368
	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% 17% 38% 22% 4	760
	11th to 20th	Night	22% 19% 34% 20% 5% 1	760
	21st to end	Night	21% 14% 38% 22% 5%	836
April	1st to 10th	Night	22% 18% 36% 20% 4	760
	11th to 20th	Night	18% 14% 34% 26% 7%	751
	21st to end	Night	21% 13% 33% 26% 8%	760
May	1st to 10th	Night	23% 10% 29% 30% 9%	604
	11th to 20th	Night	20% 8% 31% 32% 9%	374
	21st to end	Night	14% 5% 25% 40% 15% 2	411
June	1st to 10th	Night	16% 4 24% 38% 18%	380
	11th to 20th	Night	13% 4 25% 42% 16%	380
	21st to end	Night	12% 2 22% 51% 13% 1	380
July	1st to 10th	Night	11% 2 19% 44% 22% 2	370
	11th to 20th	Night	7% 2 17% 46% 26% 2	368
	21st to end	Night	11% 3 19% 41% 25% 1	543
August	1st to 10th	Night	13% 2 12% 46% 25% 2	567
	11th to 20th	Night	14% 5% 13% 39% 27% 3	665
	21st to end	Night	15% 3 16% 38% 25% 3	836
September	1st to 10th	Night	15% 4 22% 34% 21% 3	760
	11th to 20th	Night	14% 3 18% 35% 26% 4	760
	21st to end	Night	21% 5% 20% 33% 19% 2	760
October	1st to 10th	Night	22% 7% 22% 30% 16% 4	760
	11th to 20th	Night	18% 9% 27% 32% 13% 1	760
	21st to end	Night	19% 11% 30% 29% 11%	836
November	1st to 10th	Night	13% 9% 34% 31% 12% 1	745
	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 2024-10-30 01:22:58. Version ac07

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