Edinboro University Planetarium and Observatory.
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Edinboro University Planetarium and Observatory. clear sky chart from 2005-11-06 to 2024-08-15.

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	17% 13% 5% 9% 5% 4 4 3 5% 6% 29%	95350
	Night	17% 15% 5% 10% 5% 4 4 3 4 5% 28%	93314
Transparency	Day	56% 3 10% 19% 10% 1	95116
	Night	59% 3 10% 18% 9% 1	93152
Seeing	Day	26% 15% 30% 18% 8% 3	14255
	Night	26% 14% 27% 22% 9% 1	23832

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% 25% 13% 14% 5% 3 3 2 3 4 10%	2686
	11th to 20th	Day	12% 25% 10% 18% 8% 5% 3 1 3 4 12%	2840
	21st to end	Day	25% 20% 11% 18% 6% 4 3 2 2 2 7%	3124
February	1st to 10th	Day	17% 20% 7% 15% 10% 5% 3 2 3 4 15%	1710
	11th to 20th	Day	15% 18% 8% 16% 8% 5% 4 3 3 4 15%	1663
	21st to end	Day	17% 19% 4 14% 5% 3 4 3 4 5% 21%	1531
March	1st to 10th	Day	20% 13% 8% 9% 4 4 4 3 5% 6% 25%	3435
	11th to 20th	Day	11% 21% 8% 9% 4 3 4 3 4 5% 28%	3480
	21st to end	Day	21% 15% 4 11% 4 3 3 2 4 5% 27%	3815
April	1st to 10th	Day	17% 15% 4 7% 5% 4 4 3 5% 6% 30%	2199
	11th to 20th	Day	20% 14% 3 6% 4 4 4 3 5% 5% 32%	2324
	21st to end	Day	20% 14% 3 7% 4 3 4 3 4 6% 33%	2470
May	1st to 10th	Day	20% 9% 3 9% 5% 4 4 3 5% 6% 31%	4082
	11th to 20th	Day	19% 11% 3 8% 5% 4 4 3 6% 7% 30%	4132
	21st to end	Day	13% 6% 2 6% 4 5% 5% 4 6% 8% 41%	4823
June	1st to 10th	Day	17% 7% 2 6% 5% 4 4 4 6% 8% 36%	2660
	11th to 20th	Day	15% 7% 3 7% 5% 4 5% 3 6% 9% 36%	2660
	21st to end	Day	16% 6% 2 6% 4 5% 4 4 7% 8% 38%	2660
July	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 4 6% 10% 39%	4440
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 6% 9% 41%	4163
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 5% 7% 7% 39%	4466
August	1st to 10th	Day	12% 6% 2 7% 5% 6% 5% 5% 7% 9% 37%	2457
	11th to 20th	Day	13% 7% 3 8% 6% 5% 6% 5% 8% 8% 32%	2357
	21st to end	Day	14% 6% 3 7% 5% 4 5% 5% 6% 9% 37%	2480
September	1st to 10th	Day	19% 8% 3 6% 4 4 4 4 6% 8% 36%	2160
	11th to 20th	Day	13% 7% 2 7% 5% 4 5% 4 6% 7% 40%	1994
	21st to end	Day	20% 8% 3 7% 5% 4 4 4 5% 6% 34%	1976
October	1st to 10th	Day	19% 9% 2 7% 4 4 5% 4 6% 7% 33%	1800
	11th to 20th	Day	24% 10% 3 8% 6% 4 5% 3 5% 6% 26%	1800
	21st to end	Day	27% 15% 3 8% 5% 5% 5% 3 4 5% 21%	1980
November	1st to 10th	Day	14% 16% 3 8% 5% 4 4 4 5% 6% 31%	1736
	11th to 20th	Day	18% 23% 4 9% 4 4 4 3 4 6% 23%	1525
	21st to end	Day	19% 27% 7% 8% 5% 4 4 3 4 6% 14%	1520
December	1st to 10th	Day	19% 31% 9% 10% 4 3 4 3 3 3 11%	1520
	11th to 20th	Day	18% 24% 10% 14% 5% 3 3 2 4 5% 12%	1910
	21st to end	Day	26% 26% 9% 12% 4 3 2 2 2 3 10%	2772
January	1st to 10th	Night	17% 24% 12% 18% 4 4 3 2 3 3 10%	4255
	11th to 20th	Night	15% 22% 11% 19% 6% 4 4 3 3 3 10%	4120
	21st to end	Night	25% 21% 10% 16% 5% 3 3 2 2 2 10%	4532
February	1st to 10th	Night	18% 20% 5% 14% 8% 5% 3 2 3 4 17%	2470
	11th to 20th	Night	15% 18% 8% 15% 7% 6% 4 3 4 4 16%	2403
	21st to end	Night	19% 15% 6% 16% 6% 4 4 3 3 4 21%	1919
March	1st to 10th	Night	21% 17% 4 8% 5% 3 3 2 3 5% 28%	3418
	11th to 20th	Night	17% 17% 9% 9% 4 2 3 3 4 5% 28%	3480
	21st to end	Night	17% 14% 5% 10% 5% 3 3 3 3 3 34%	3817
April	1st to 10th	Night	18% 17% 4 6% 4 4 3 4 4 5% 29%	1981
	11th to 20th	Night	19% 11% 2 7% 5% 4 4 3 5% 6% 32%	1820
	21st to end	Night	15% 12% 3 7% 5% 4 4 4 5% 7% 33%	1710
May	1st to 10th	Night	25% 10% 2 7% 3 4 3 3 4 6% 32%	2813
	11th to 20th	Night	16% 10% 3 7% 5% 4 4 3 5% 7% 35%	2759
	21st to end	Night	14% 5% 2 4 4 3 4 3 6% 11% 45%	2732
June	1st to 10th	Night	11% 6% 3 6% 5% 6% 5% 4 7% 8% 39%	1520
	11th to 20th	Night	11% 7% 3 7% 6% 4 4 4 7% 7% 42%	1520
	21st to end	Night	13% 7% 2 6% 4 5% 5% 4 6% 9% 40%	1520
July	1st to 10th	Night	12% 8% 3 7% 5% 3 4 3 5% 8% 41%	2520
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 6% 9% 44%	2793
	21st to end	Night	9% 6% 2 6% 4 5% 5% 4 6% 8% 44%	3087
August	1st to 10th	Night	9% 7% 3 5% 4 4 5% 4 6% 8% 46%	1701
	11th to 20th	Night	9% 7% 2 6% 4 5% 6% 5% 6% 8% 42%	1643
	21st to end	Night	12% 5% 2 6% 3 5% 4 4 6% 8% 44%	1858
September	1st to 10th	Night	14% 7% 2 6% 4 3 4 4 5% 7% 43%	1800
	11th to 20th	Night	13% 6% 2 5% 4 4 3 3 6% 7% 48%	1962
	21st to end	Night	18% 8% 2 7% 4 4 5% 3 6% 7% 37%	1983
October	1st to 10th	Night	19% 6% 2 6% 4 4 4 3 5% 7% 40%	2160
	11th to 20th	Night	22% 10% 2 8% 5% 5% 5% 4 5% 5% 29%	2160
	21st to end	Night	28% 13% 3 7% 4 4 4 2 4 5% 25%	2376
November	1st to 10th	Night	16% 13% 3 8% 4 4 4 3 6% 6% 32%	2341
	11th to 20th	Night	19% 20% 4 9% 4 4 5% 3 5% 5% 22%	2652
	21st to end	Night	19% 23% 6% 9% 4 4 4 3 4 5% 19%	2660
December	1st to 10th	Night	21% 26% 9% 10% 5% 4 3 2 3 4 13%	2660
	11th to 20th	Night	17% 25% 9% 14% 5% 4 3 2 3 4 15%	3285
	21st to end	Night	24% 26% 8% 11% 6% 4 4 3 4 3 8%	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	82% 1 7% 7% 3	2687
	11th to 20th	Day	79% 1 7% 10% 3	2840
	21st to end	Day	87% 1 5% 5% 2	3124
February	1st to 10th	Day	77% 2 7% 10% 4	1710
	11th to 20th	Day	75% 3 5% 12% 6%	1672
	21st to end	Day	67% 2 9% 15% 5% 2	1531
March	1st to 10th	Day	62% 2 8% 24% 4	3435
	11th to 20th	Day	61% 2 15% 16% 5% 1	3480
	21st to end	Day	62% 1 6% 19% 11% 1	3815
April	1st to 10th	Day	56% 2 11% 18% 12% 1	2199
	11th to 20th	Day	54% 3 9% 21% 12% 2	2324
	21st to end	Day	55% 2 10% 20% 11% 3	2470
May	1st to 10th	Day	56% 2 7% 24% 10% 1	4120
	11th to 20th	Day	54% 2 11% 23% 9% 1	4136
	21st to end	Day	42% 3 13% 23% 16% 4	4837
June	1st to 10th	Day	46% 3 12% 25% 13% 1	2660
	11th to 20th	Day	45% 4 14% 24% 13% 1	2660
	21st to end	Day	43% 4 11% 27% 14% 1	2660
July	1st to 10th	Day	39% 5% 13% 25% 16% 2	4370
	11th to 20th	Day	38% 5% 12% 26% 17% 1	4092
	21st to end	Day	40% 7% 12% 24% 16% 1	4324
August	1st to 10th	Day	43% 4 13% 29% 11%	2444
	11th to 20th	Day	46% 4 15% 25% 8% 2	2357
	21st to end	Day	43% 5% 11% 24% 15% 2	2480
September	1st to 10th	Day	46% 4 13% 22% 13% 2	2160
	11th to 20th	Day	43% 4 12% 26% 15% 1	1994
	21st to end	Day	51% 3 11% 24% 12% 1	1976
October	1st to 10th	Day	50% 4 13% 20% 12% 2	1800
	11th to 20th	Day	59% 2 12% 19% 7% 1	1800
	21st to end	Day	67% 2 10% 13% 7% 1	1980
November	1st to 10th	Day	55% 3 9% 19% 12% 2	1736
	11th to 20th	Day	65% 3 10% 14% 6% 2	1525
	21st to end	Day	74% 3 9% 10% 5% 1	1520
December	1st to 10th	Day	80% 2 7% 9% 2	1520
	11th to 20th	Day	77% 2 8% 11% 2	1906
	21st to end	Day	83% 1 8% 7% 1	2772
January	1st to 10th	Night	83% 1 6% 8% 2	4255
	11th to 20th	Night	81% 1 7% 8% 2	4120
	21st to end	Night	84% 1 6% 8% 2	4532
February	1st to 10th	Night	74% 2 7% 12% 4	2470
	11th to 20th	Night	73% 2 7% 13% 4	2405
	21st to end	Night	69% 2 9% 12% 7% 1	1919
March	1st to 10th	Night	61% 2 9% 22% 6%	3418
	11th to 20th	Night	62% 1 12% 18% 7% 1	3480
	21st to end	Night	57% 1 7% 18% 14% 2	3817
April	1st to 10th	Night	58% 3 9% 17% 12% 1	1981
	11th to 20th	Night	53% 3 10% 19% 13% 3	1820
	21st to end	Night	51% 3 11% 21% 11% 3	1710
May	1st to 10th	Night	55% 2 8% 20% 12% 3	2840
	11th to 20th	Night	50% 3 11% 24% 11% 2	2760
	21st to end	Night	36% 3 12% 29% 16% 3	2739
June	1st to 10th	Night	41% 5% 12% 25% 15% 2	1520
	11th to 20th	Night	41% 3 13% 24% 17% 2	1520
	21st to end	Night	41% 5% 13% 24% 16% 1	1520
July	1st to 10th	Night	42% 4 11% 22% 18% 3	2480
	11th to 20th	Night	37% 5% 13% 27% 17% 2	2741
	21st to end	Night	37% 7% 12% 23% 21% 1	2988
August	1st to 10th	Night	37% 4 12% 33% 14% 1	1690
	11th to 20th	Night	38% 5% 16% 29% 11% 1	1643
	21st to end	Night	38% 4 13% 25% 17% 3	1858
September	1st to 10th	Night	39% 4 13% 27% 14% 3	1800
	11th to 20th	Night	37% 3 12% 27% 19% 1	1962
	21st to end	Night	48% 2 12% 23% 14% 1	1983
October	1st to 10th	Night	45% 3 11% 23% 16% 1	2160
	11th to 20th	Night	56% 3 11% 18% 11% 1	2160
	21st to end	Night	63% 2 10% 15% 8% 2	2376
November	1st to 10th	Night	53% 3 11% 22% 10% 2	2341
	11th to 20th	Night	64% 3 8% 15% 7% 3	2652
	21st to end	Night	69% 2 10% 14% 3 1	2660
December	1st to 10th	Night	78% 2 8% 10% 2	2660
	11th to 20th	Night	77% 1 10% 10% 2	3288
	21st to end	Night	83% 2 8% 7% 1	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	34% 25% 29% 10% 3	229
	11th to 20th	Day	33% 30% 27% 6% 3 1	270
	21st to end	Day	34% 29% 28% 7% 2	297
February	1st to 10th	Day	38% 21% 35% 6%	270
	11th to 20th	Day	39% 24% 30% 6% 1	270
	21st to end	Day	44% 24% 27% 5%	234
March	1st to 10th	Day	33% 23% 32% 10% 3	460
	11th to 20th	Day	33% 20% 33% 11% 2 1	460
	21st to end	Day	38% 21% 25% 13% 2	506
April	1st to 10th	Day	31% 22% 30% 11% 5% 1	460
	11th to 20th	Day	35% 18% 26% 12% 8% 2	452
	21st to end	Day	30% 19% 31% 14% 4 1	460
May	1st to 10th	Day	31% 14% 33% 16% 4 2	463
	11th to 20th	Day	26% 14% 27% 21% 10% 2	487
	21st to end	Day	17% 9% 33% 24% 12% 5%	529
June	1st to 10th	Day	20% 12% 30% 25% 9% 3	490
	11th to 20th	Day	22% 9% 27% 27% 12% 2	490
	21st to end	Day	19% 10% 34% 24% 10% 2	490
July	1st to 10th	Day	12% 6% 28% 30% 17% 7%	485
	11th to 20th	Day	17% 7% 32% 27% 13% 5%	484
	21st to end	Day	11% 8% 35% 27% 16% 3	532
August	1st to 10th	Day	14% 8% 26% 29% 16% 7%	486
	11th to 20th	Day	17% 3 27% 32% 13% 8%	456
	21st to end	Day	15% 7% 27% 29% 16% 6%	495
September	1st to 10th	Day	21% 6% 26% 25% 16% 5%	450
	11th to 20th	Day	13% 5% 28% 28% 19% 7%	450
	21st to end	Day	24% 11% 28% 20% 11% 5%	450
October	1st to 10th	Day	21% 14% 27% 20% 13% 3	450
	11th to 20th	Day	30% 18% 31% 15% 6% 1	450
	21st to end	Day	39% 15% 32% 12% 2	495
November	1st to 10th	Day	31% 17% 29% 17% 5% 1	334
	11th to 20th	Day	39% 19% 30% 8% 4	183
	21st to end	Day	36% 20% 37% 7%	180
December	1st to 10th	Day	42% 25% 26% 3 4 1	180
	11th to 20th	Day	41% 23% 27% 7% 2	180
	21st to end	Day	37% 22% 33% 7% 1	198
January	1st to 10th	Night	35% 23% 29% 10% 3	760
	11th to 20th	Night	37% 21% 27% 14% 2	760
	21st to end	Night	29% 23% 31% 15% 2	836
February	1st to 10th	Night	36% 19% 29% 14% 1	760
	11th to 20th	Night	30% 25% 30% 13% 2	743
	21st to end	Night	32% 21% 30% 14% 2	628
March	1st to 10th	Night	28% 21% 31% 16% 5%	760
	11th to 20th	Night	29% 19% 30% 18% 4	760
	21st to end	Night	28% 16% 31% 19% 5%	836
April	1st to 10th	Night	30% 16% 31% 19% 5%	760
	11th to 20th	Night	29% 11% 32% 20% 7% 1	696
	21st to end	Night	24% 11% 33% 27% 5%	570
May	1st to 10th	Night	26% 9% 27% 28% 9% 1	570
	11th to 20th	Night	19% 9% 31% 33% 8% 1	534
	21st to end	Night	13% 7% 30% 30% 19% 2	411
June	1st to 10th	Night	14% 4 32% 35% 14%	380
	11th to 20th	Night	13% 8% 26% 41% 12%	380
	21st to end	Night	14% 6% 29% 34% 16% 1	380
July	1st to 10th	Night	13% 3 19% 40% 20% 5%	370
	11th to 20th	Night	13% 3 21% 35% 23% 4	520
	21st to end	Night	13% 3 19% 38% 27% 1	624
August	1st to 10th	Night	11% 3 19% 39% 24% 3	567
	11th to 20th	Night	13% 4 16% 36% 28% 4	549
	21st to end	Night	16% 3 22% 30% 25% 3	670
September	1st to 10th	Night	18% 5% 18% 33% 22% 4	720
	11th to 20th	Night	15% 5% 22% 32% 23% 5%	720
	21st to end	Night	23% 9% 22% 27% 15% 4	720
October	1st to 10th	Night	21% 6% 29% 26% 16% 2	720
	11th to 20th	Night	30% 13% 28% 22% 7%	720
	21st to end	Night	37% 14% 29% 18% 2	792
November	1st to 10th	Night	26% 14% 29% 24% 8%	740
	11th to 20th	Night	34% 20% 28% 13% 5% 1	760
	21st to end	Night	35% 19% 30% 12% 4	760
December	1st to 10th	Night	38% 22% 26% 11% 3	760
	11th to 20th	Night	34% 26% 25% 13% 2	760
	21st to end	Night	37% 20% 30% 12% 1	836

Page generated at 2024-08-12 09:52:53. Version ac07

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