Susquehanna University
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Susquehanna University clear sky chart from 2005-11-06 to 2024-01-12.

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% 7% 3 6% 6% 4 5% 5% 5% 7% 36%	74695
	Night	16% 8% 3 6% 5% 3 4 5% 5% 7% 38%	75018
Transparency	Day	46% 7% 12% 21% 12% 2	74408
	Night	44% 7% 13% 21% 13% 2	74839
Seeing	Day	21% 17% 27% 20% 11% 3	13686
	Night	19% 13% 29% 27% 10% 1	23170

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	13% 8% 4 7% 7% 4 6% 5% 5% 6% 35%	1517
	11th to 20th	Day	16% 10% 5% 10% 7% 4 5% 5% 4 6% 26%	1566
	21st to end	Day	14% 11% 4 9% 8% 4 5% 5% 5% 7% 28%	1782
February	1st to 10th	Day	18% 10% 4 7% 7% 4 5% 5% 5% 6% 27%	1620
	11th to 20th	Day	14% 9% 5% 8% 7% 4 5% 5% 4 7% 31%	1607
	21st to end	Day	19% 10% 4 8% 7% 3 5% 5% 4 4 32%	1480
March	1st to 10th	Day	14% 8% 4 6% 6% 3 5% 4 4 5% 40%	1895
	11th to 20th	Day	17% 8% 3 8% 6% 3 5% 5% 5% 8% 32%	1980
	21st to end	Day	20% 9% 4 7% 5% 3 4 3 4 6% 36%	2235
April	1st to 10th	Day	15% 9% 3 6% 6% 4 4 4 5% 7% 36%	2160
	11th to 20th	Day	17% 7% 3 5% 6% 3 4 5% 5% 6% 39%	2134
	21st to end	Day	19% 6% 2 5% 5% 4 5% 5% 5% 6% 37%	2160
May	1st to 10th	Day	18% 7% 3 7% 5% 3 5% 5% 4 6% 35%	2370
	11th to 20th	Day	20% 6% 3 6% 6% 3 5% 5% 5% 6% 34%	2478
	21st to end	Day	14% 6% 2 5% 5% 4 5% 6% 6% 8% 39%	2725
June	1st to 10th	Day	13% 6% 3 6% 7% 4 6% 5% 6% 8% 37%	2520
	11th to 20th	Day	13% 6% 3 7% 6% 3 6% 5% 5% 9% 38%	2520
	21st to end	Day	11% 5% 2 5% 5% 4 5% 5% 7% 10% 41%	2520
July	1st to 10th	Day	9% 6% 2 6% 6% 4 7% 6% 7% 9% 38%	2520
	11th to 20th	Day	7% 5% 3 6% 6% 4 6% 6% 8% 10% 41%	2520
	21st to end	Day	10% 6% 4 6% 6% 4 7% 6% 6% 8% 37%	2609
August	1st to 10th	Day	10% 6% 3 5% 6% 4 6% 7% 7% 8% 37%	2327
	11th to 20th	Day	12% 7% 3 6% 6% 4 5% 6% 6% 9% 36%	2231
	21st to end	Day	13% 5% 2 5% 6% 4 6% 5% 6% 10% 38%	2376
September	1st to 10th	Day	16% 6% 2 5% 5% 3 4 5% 5% 6% 43%	2160
	11th to 20th	Day	14% 5% 2 4 4 3 4 4 4 7% 49%	2160
	21st to end	Day	18% 8% 2 5% 4 3 4 4 4 7% 41%	1903
October	1st to 10th	Day	18% 7% 2 5% 4 3 5% 4 5% 6% 40%	1800
	11th to 20th	Day	18% 7% 3 5% 5% 3 5% 5% 4 7% 38%	1800
	21st to end	Day	20% 7% 3 5% 5% 3 5% 5% 5% 6% 35%	1980
November	1st to 10th	Day	13% 7% 2 5% 5% 3 4 4 4 7% 46%	1684
	11th to 20th	Day	19% 6% 3 5% 4 4 5% 4 6% 6% 38%	1638
	21st to end	Day	18% 6% 2 6% 6% 3 6% 6% 5% 6% 36%	1520
December	1st to 10th	Day	19% 10% 5% 7% 8% 3 5% 5% 4 6% 28%	1520
	11th to 20th	Day	22% 10% 2 6% 6% 3 3 4 5% 7% 33%	1906
	21st to end	Day	21% 12% 4 7% 7% 4 5% 5% 5% 5% 23%	2772
January	1st to 10th	Night	15% 10% 4 6% 6% 4 5% 5% 4 6% 35%	2649
	11th to 20th	Night	18% 10% 4 7% 6% 4 5% 4 5% 6% 32%	2432
	21st to end	Night	13% 9% 4 7% 7% 3 5% 5% 6% 6% 35%	2574
February	1st to 10th	Night	17% 10% 3 7% 7% 3 5% 4 6% 6% 32%	2340
	11th to 20th	Night	16% 9% 4 7% 6% 3 5% 5% 5% 7% 33%	2238
	21st to end	Night	18% 9% 3 7% 7% 3 5% 5% 4 5% 34%	1776
March	1st to 10th	Night	15% 7% 2 6% 5% 3 4 4 6% 6% 41%	2047
	11th to 20th	Night	18% 9% 2 5% 5% 2 5% 3 5% 6% 40%	1979
	21st to end	Night	17% 7% 4 5% 6% 3 5% 5% 5% 6% 37%	2120
April	1st to 10th	Night	17% 9% 4 7% 5% 3 5% 5% 5% 7% 34%	1800
	11th to 20th	Night	15% 5% 3 7% 6% 3 5% 5% 5% 8% 39%	1775
	21st to end	Night	19% 6% 3 5% 5% 3 4 5% 5% 6% 42%	1800
May	1st to 10th	Night	19% 9% 3 6% 5% 3 3 5% 4 7% 37%	1602
	11th to 20th	Night	17% 5% 3 5% 6% 3 5% 4 6% 6% 40%	1415
	21st to end	Night	12% 6% 3 6% 6% 3 5% 5% 5% 8% 41%	1550
June	1st to 10th	Night	14% 5% 3 5% 4 3 4 4 6% 8% 44%	1440
	11th to 20th	Night	12% 6% 2 6% 6% 3 5% 6% 6% 9% 40%	1440
	21st to end	Night	10% 5% 2 4 5% 4 4 7% 7% 10% 42%	1440
July	1st to 10th	Night	11% 5% 3 5% 6% 3 6% 5% 5% 9% 42%	1440
	11th to 20th	Night	8% 4 3 5% 4 4 6% 5% 7% 10% 43%	1440
	21st to end	Night	10% 5% 2 4 5% 3 5% 6% 6% 10% 42%	1705
August	1st to 10th	Night	11% 5% 2 6% 5% 4 4 5% 8% 9% 41%	1611
	11th to 20th	Night	12% 7% 3 6% 5% 4 5% 5% 6% 9% 38%	1651
	21st to end	Night	12% 5% 3 5% 5% 3 5% 6% 7% 8% 42%	1980
September	1st to 10th	Night	15% 5% 2 5% 6% 3 4 4 5% 7% 44%	1800
	11th to 20th	Night	11% 5% 2 5% 4 2 3 4 4 8% 52%	1800
	21st to end	Night	18% 5% 2 5% 3 3 4 4 5% 6% 44%	2053
October	1st to 10th	Night	19% 7% 2 5% 4 3 3 3 5% 7% 41%	2160
	11th to 20th	Night	17% 6% 3 4 5% 3 4 4 4 7% 43%	2160
	21st to end	Night	21% 7% 2 5% 5% 3 4 4 5% 7% 38%	2376
November	1st to 10th	Night	11% 7% 3 5% 5% 2 4 4 4 6% 50%	2393
	11th to 20th	Night	17% 9% 3 5% 5% 3 3 4 5% 7% 40%	2540
	21st to end	Night	16% 8% 3 5% 6% 3 4 4 5% 7% 38%	2660
December	1st to 10th	Night	18% 10% 4 7% 5% 3 5% 5% 5% 7% 31%	2660
	11th to 20th	Night	19% 10% 3 6% 5% 3 5% 4 5% 6% 34%	3288
	21st to end	Night	20% 11% 4 8% 6% 4 5% 5% 5% 7% 26%	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	48% 6% 14% 21% 9% 1	1518
	11th to 20th	Day	59% 7% 11% 15% 7% 1	1566
	21st to end	Day	56% 6% 11% 18% 8% 1	1782
February	1st to 10th	Day	55% 6% 13% 16% 9% 1	1620
	11th to 20th	Day	53% 7% 10% 22% 8% 1	1616
	21st to end	Day	55% 5% 10% 19% 9% 2	1480
March	1st to 10th	Day	46% 6% 11% 24% 11% 2	1898
	11th to 20th	Day	49% 6% 11% 19% 11% 4	1980
	21st to end	Day	51% 4 9% 18% 15% 3	2235
April	1st to 10th	Day	48% 7% 11% 19% 12% 4	2160
	11th to 20th	Day	44% 6% 11% 20% 15% 3	2134
	21st to end	Day	45% 7% 10% 20% 13% 4	2160
May	1st to 10th	Day	48% 7% 10% 18% 13% 3	2370
	11th to 20th	Day	51% 7% 10% 17% 12% 3	2482
	21st to end	Day	42% 9% 14% 21% 12% 2	2725
June	1st to 10th	Day	44% 8% 12% 21% 13% 2	2520
	11th to 20th	Day	43% 8% 14% 20% 12% 2	2520
	21st to end	Day	36% 9% 15% 27% 13% 1	2520
July	1st to 10th	Day	40% 11% 12% 22% 13% 1	2450
	11th to 20th	Day	35% 9% 14% 26% 14% 2	2445
	21st to end	Day	41% 9% 13% 20% 15% 1	2463
August	1st to 10th	Day	40% 10% 16% 22% 13%	2314
	11th to 20th	Day	42% 9% 15% 21% 12% 1	2231
	21st to end	Day	40% 7% 13% 22% 15% 3	2376
September	1st to 10th	Day	41% 7% 12% 21% 16% 3	2160
	11th to 20th	Day	34% 6% 11% 25% 21% 3	2160
	21st to end	Day	44% 6% 10% 19% 18% 2	1903
October	1st to 10th	Day	43% 7% 13% 22% 14% 1	1800
	11th to 20th	Day	43% 7% 12% 24% 14%	1800
	21st to end	Day	47% 7% 12% 22% 11% 2	1980
November	1st to 10th	Day	39% 5% 14% 24% 16% 3	1684
	11th to 20th	Day	45% 7% 12% 22% 13% 2	1638
	21st to end	Day	47% 6% 13% 26% 8% 1	1520
December	1st to 10th	Day	56% 7% 14% 16% 7% 1	1520
	11th to 20th	Day	50% 6% 17% 21% 5%	1906
	21st to end	Day	60% 7% 15% 13% 5%	2772
January	1st to 10th	Night	48% 6% 12% 22% 10% 2	2649
	11th to 20th	Night	52% 7% 15% 17% 7% 2	2432
	21st to end	Night	48% 6% 13% 20% 11% 2	2574
February	1st to 10th	Night	51% 7% 13% 21% 7% 1	2340
	11th to 20th	Night	51% 6% 12% 20% 11% 1	2240
	21st to end	Night	52% 6% 9% 18% 13% 2	1776
March	1st to 10th	Night	42% 6% 12% 25% 13% 2	2057
	11th to 20th	Night	45% 6% 10% 22% 14% 2	1980
	21st to end	Night	48% 6% 10% 18% 15% 3	2120
April	1st to 10th	Night	50% 6% 10% 19% 13% 2	1800
	11th to 20th	Night	42% 6% 12% 21% 17% 2	1775
	21st to end	Night	42% 6% 12% 22% 15% 3	1800
May	1st to 10th	Night	48% 7% 9% 20% 11% 4	1602
	11th to 20th	Night	44% 8% 12% 16% 18% 2	1416
	21st to end	Night	41% 9% 15% 18% 14% 3	1551
June	1st to 10th	Night	38% 8% 11% 23% 18% 1	1440
	11th to 20th	Night	39% 9% 14% 20% 15% 2	1440
	21st to end	Night	34% 9% 14% 27% 14% 1	1440
July	1st to 10th	Night	39% 10% 15% 20% 13% 4	1400
	11th to 20th	Night	34% 9% 15% 25% 16% 2	1392
	21st to end	Night	33% 11% 17% 22% 15% 2	1610
August	1st to 10th	Night	35% 11% 17% 22% 15% 1	1600
	11th to 20th	Night	41% 10% 14% 18% 17% 1	1651
	21st to end	Night	36% 10% 13% 21% 17% 3	1980
September	1st to 10th	Night	39% 6% 12% 23% 16% 3	1800
	11th to 20th	Night	31% 6% 11% 29% 20% 3	1800
	21st to end	Night	40% 5% 10% 23% 20% 2	2053
October	1st to 10th	Night	42% 6% 13% 23% 15% 1	2160
	11th to 20th	Night	40% 7% 13% 26% 13% 2	2160
	21st to end	Night	45% 7% 11% 23% 13% 1	2376
November	1st to 10th	Night	35% 6% 13% 25% 18% 3	2393
	11th to 20th	Night	44% 5% 11% 23% 14% 3	2540
	21st to end	Night	44% 6% 15% 23% 9% 2	2660
December	1st to 10th	Night	51% 8% 14% 18% 9%	2660
	11th to 20th	Night	51% 6% 13% 19% 10% 1	3288
	21st to end	Night	54% 8% 16% 17% 4	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	33% 24% 26% 14% 2 1	180
	11th to 20th	Day	30% 26% 30% 13% 1	214
	21st to end	Day	25% 34% 26% 10% 4	264
February	1st to 10th	Day	32% 29% 29% 8% 1	240
	11th to 20th	Day	31% 28% 38% 3	274
	21st to end	Day	34% 23% 27% 15% 2	346
March	1st to 10th	Day	30% 21% 29% 17% 3	420
	11th to 20th	Day	27% 26% 28% 14% 3 1	420
	21st to end	Day	29% 25% 24% 15% 4 2	462
April	1st to 10th	Day	23% 26% 29% 15% 5% 1	420
	11th to 20th	Day	22% 27% 24% 16% 7% 4	412
	21st to end	Day	26% 18% 34% 13% 7% 1	420
May	1st to 10th	Day	27% 22% 27% 13% 8% 2	423
	11th to 20th	Day	23% 19% 29% 19% 8% 2	447
	21st to end	Day	20% 10% 26% 20% 19% 5%	485
June	1st to 10th	Day	17% 12% 30% 26% 12% 3	450
	11th to 20th	Day	16% 15% 29% 24% 13% 3	450
	21st to end	Day	12% 13% 33% 27% 13% 2	450
July	1st to 10th	Day	11% 6% 26% 31% 20% 7%	445
	11th to 20th	Day	5% 6% 28% 33% 23% 5%	444
	21st to end	Day	12% 9% 28% 31% 16% 4	488
August	1st to 10th	Day	13% 8% 22% 28% 21% 7%	446
	11th to 20th	Day	13% 7% 24% 29% 19% 8%	439
	21st to end	Day	13% 8% 23% 30% 15% 11%	495
September	1st to 10th	Day	18% 10% 20% 23% 19% 11%	450
	11th to 20th	Day	15% 6% 24% 26% 20% 9%	450
	21st to end	Day	23% 14% 23% 20% 16% 4	450
October	1st to 10th	Day	22% 10% 24% 23% 17% 5%	450
	11th to 20th	Day	21% 15% 29% 23% 11% 1	450
	21st to end	Day	22% 17% 32% 19% 9%	495
November	1st to 10th	Day	21% 15% 27% 22% 12% 2	371
	11th to 20th	Day	27% 19% 28% 17% 9%	298
	21st to end	Day	23% 25% 35% 13% 3 1	180
December	1st to 10th	Day	29% 28% 29% 9% 4 1	180
	11th to 20th	Day	33% 22% 31% 11% 3	180
	21st to end	Day	26% 28% 26% 17% 3	198
January	1st to 10th	Night	20% 21% 40% 17% 3	760
	11th to 20th	Night	23% 18% 34% 21% 3	728
	21st to end	Night	17% 22% 38% 22% 2	792
February	1st to 10th	Night	25% 18% 34% 23% 1	720
	11th to 20th	Night	24% 22% 39% 15% 1	703
	21st to end	Night	26% 21% 34% 16% 2	592
March	1st to 10th	Night	23% 20% 33% 22% 3	720
	11th to 20th	Night	26% 17% 33% 20% 4	720
	21st to end	Night	23% 16% 35% 19% 6% 1	792
April	1st to 10th	Night	23% 20% 32% 21% 5%	720
	11th to 20th	Night	20% 15% 33% 23% 7%	711
	21st to end	Night	21% 15% 30% 28% 5%	720
May	1st to 10th	Night	23% 11% 30% 24% 11%	522
	11th to 20th	Night	18% 8% 34% 32% 7%	354
	21st to end	Night	16% 8% 23% 37% 15% 1	389
June	1st to 10th	Night	15% 5% 25% 37% 18%	360
	11th to 20th	Night	14% 6% 26% 40% 13%	360
	21st to end	Night	12% 3 25% 48% 12% 1	360
July	1st to 10th	Night	14% 1 24% 37% 21% 3	350
	11th to 20th	Night	9% 3 18% 46% 24% 1	348
	21st to end	Night	10% 4 22% 41% 22% 1	525
August	1st to 10th	Night	12% 2 15% 43% 25% 2	537
	11th to 20th	Night	12% 4 15% 36% 29% 3	587
	21st to end	Night	11% 5% 19% 34% 28% 2	792
September	1st to 10th	Night	15% 4 23% 36% 20% 2	720
	11th to 20th	Night	13% 5% 22% 31% 25% 4	720
	21st to end	Night	19% 7% 23% 32% 18% 2	720
October	1st to 10th	Night	21% 9% 23% 27% 19% 2	720
	11th to 20th	Night	18% 11% 29% 31% 10%	720
	21st to end	Night	24% 13% 29% 27% 7%	792
November	1st to 10th	Night	15% 13% 31% 30% 10% 1	740
	11th to 20th	Night	21% 18% 30% 23% 7% 1	760
	21st to end	Night	20% 18% 33% 24% 6%	760
December	1st to 10th	Night	26% 17% 33% 19% 5%	760
	11th to 20th	Night	22% 17% 34% 24% 3	760
	21st to end	Night	23% 17% 34% 24% 2	836

Page generated at 2024-01-09 16:24:27. Version ac07

Copyright 2024 Attilla Danko