Silver Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Silver Creek Observatory 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	14% 5% 2 5% 5% 3 5% 5% 6% 8% 43%	78922
	Night	14% 6% 2 5% 5% 3 4 5% 5% 7% 44%	80608
Transparency	Day	38% 7% 12% 20% 18% 4	78645
	Night	38% 7% 11% 20% 19% 5%	80404
Seeing	Day	17% 9% 21% 25% 18% 10%	14179
	Night	16% 7% 21% 32% 21% 4	24363

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	16% 4 2 3 3 2 3 3 4 7% 54%	2836
	11th to 20th	Day	14% 6% 2 4 4 2 4 4 4 5% 51%	2840
	21st to end	Day	24% 5% 1 4 4 3 3 3 4 5% 45%	3124
February	1st to 10th	Day	15% 6% 2 5% 5% 3 3 4 6% 8% 43%	1729
	11th to 20th	Day	18% 7% 2 5% 4 2 3 4 5% 6% 43%	1848
	21st to end	Day	18% 6% 3 4 5% 3 5% 4 4 5% 42%	1570
March	1st to 10th	Day	15% 4 2 4 4 2 3 4 4 6% 50%	2030
	11th to 20th	Day	18% 5% 3 6% 5% 3 4 6% 5% 6% 39%	1980
	21st to end	Day	17% 7% 2 5% 4 3 5% 5% 5% 7% 41%	2178
April	1st to 10th	Day	11% 4 2 4 4 2 5% 5% 6% 8% 49%	1980
	11th to 20th	Day	16% 4 2 4 4 2 4 5% 5% 7% 46%	2132
	21st to end	Day	13% 5% 3 4 5% 3 5% 5% 5% 7% 45%	2340
May	1st to 10th	Day	10% 5% 3 4 5% 4 5% 5% 7% 9% 43%	2340
	11th to 20th	Day	15% 6% 2 5% 6% 4 5% 6% 6% 8% 37%	2301
	21st to end	Day	13% 5% 2 5% 5% 3 5% 6% 7% 9% 39%	2531
June	1st to 10th	Day	11% 6% 3 6% 6% 3 7% 7% 7% 10% 36%	2340
	11th to 20th	Day	8% 5% 2 5% 6% 4 6% 7% 9% 10% 38%	2340
	21st to end	Day	7% 4 2 5% 6% 5% 7% 7% 8% 11% 38%	2340
July	1st to 10th	Day	9% 5% 3 6% 7% 4 8% 7% 8% 10% 32%	2340
	11th to 20th	Day	9% 6% 3 6% 7% 4 7% 7% 9% 11% 29%	2340
	21st to end	Day	9% 4 2 6% 6% 5% 8% 8% 8% 11% 33%	2547
August	1st to 10th	Day	12% 6% 3 7% 7% 5% 8% 7% 8% 10% 27%	2327
	11th to 20th	Day	13% 5% 3 7% 7% 5% 7% 7% 7% 10% 30%	2303
	21st to end	Day	11% 5% 3 7% 6% 4 6% 7% 7% 10% 35%	2427
September	1st to 10th	Day	12% 5% 3 5% 6% 4 5% 5% 6% 8% 42%	1980
	11th to 20th	Day	15% 7% 2 5% 5% 4 4 4 6% 7% 40%	1980
	21st to end	Day	19% 5% 2 5% 4 3 5% 4 5% 7% 41%	1980
October	1st to 10th	Day	16% 5% 2 4 4 2 2 3 4 6% 53%	1906
	11th to 20th	Day	14% 4 2 3 4 2 3 3 4 5% 57%	1800
	21st to end	Day	15% 4 2 4 4 2 2 3 3 4 57%	1980
November	1st to 10th	Day	12% 6% 1 3 3 2 3 3 4 6% 58%	1826
	11th to 20th	Day	13% 5% 2 4 4 2 3 3 4 7% 54%	1710
	21st to end	Day	15% 3 1 3 4 2 4 4 5% 7% 52%	1710
December	1st to 10th	Day	17% 9% 3 5% 4 3 5% 4 5% 5% 41%	1710
	11th to 20th	Day	14% 5% 1 4 3 1 3 4 5% 7% 52%	2153
	21st to end	Day	19% 6% 2 4 4 3 4 4 5% 6% 43%	3124
January	1st to 10th	Night	15% 5% 2 4 5% 2 3 4 4 6% 50%	4109
	11th to 20th	Night	13% 6% 2 4 4 3 4 4 5% 5% 49%	4120
	21st to end	Night	23% 7% 2 5% 4 2 3 4 4 5% 42%	4532
February	1st to 10th	Night	14% 5% 2 4 5% 3 4 5% 5% 7% 45%	2447
	11th to 20th	Night	19% 6% 3 4 4 2 4 4 5% 5% 45%	2218
	21st to end	Night	16% 6% 3 5% 5% 3 5% 4 6% 7% 41%	1884
March	1st to 10th	Night	13% 5% 2 5% 5% 2 4 4 6% 6% 48%	2046
	11th to 20th	Night	16% 6% 3 6% 5% 3 4 5% 4 8% 41%	1980
	21st to end	Night	18% 5% 2 5% 6% 2 5% 4 5% 7% 41%	2178
April	1st to 10th	Night	11% 6% 2 4 3 2 5% 5% 5% 7% 50%	1980
	11th to 20th	Night	13% 5% 2 4 4 3 3 3 6% 8% 48%	1791
	21st to end	Night	13% 4 2 5% 4 2 4 3 5% 6% 51%	1620
May	1st to 10th	Night	12% 5% 2 5% 6% 4 4 4 5% 8% 44%	1620
	11th to 20th	Night	14% 7% 3 7% 7% 4 5% 5% 6% 7% 36%	1592
	21st to end	Night	14% 5% 2 6% 5% 3 4 4 5% 10% 41%	1744
June	1st to 10th	Night	9% 5% 2 6% 5% 4 7% 7% 9% 11% 35%	1620
	11th to 20th	Night	9% 5% 3 6% 6% 3 5% 6% 6% 9% 42%	1620
	21st to end	Night	7% 3 2 6% 6% 4 6% 7% 8% 12% 38%	1620
July	1st to 10th	Night	8% 5% 4 7% 7% 4 5% 7% 8% 9% 34%	1620
	11th to 20th	Night	9% 5% 3 6% 7% 5% 6% 7% 10% 10% 34%	1620
	21st to end	Night	6% 5% 2 6% 7% 4 8% 7% 9% 13% 34%	1771
August	1st to 10th	Night	13% 7% 3 7% 5% 4 5% 7% 7% 10% 33%	1611
	11th to 20th	Night	12% 8% 2 6% 6% 4 5% 7% 6% 10% 34%	1598
	21st to end	Night	10% 6% 3 7% 7% 4 5% 6% 7% 11% 35%	1906
September	1st to 10th	Night	11% 5% 3 6% 6% 4 5% 5% 6% 7% 43%	1980
	11th to 20th	Night	16% 7% 2 6% 5% 3 6% 5% 5% 7% 38%	1980
	21st to end	Night	18% 6% 3 5% 5% 2 5% 3 5% 6% 42%	1980
October	1st to 10th	Night	18% 4 2 4 4 2 4 4 4 5% 50%	2052
	11th to 20th	Night	15% 5% 2 4 3 2 5% 4 4 5% 51%	2160
	21st to end	Night	14% 4 2 3 3 2 3 3 4 4 57%	2376
November	1st to 10th	Night	13% 5% 2 5% 4 2 4 3 3 4 55%	2249
	11th to 20th	Night	13% 5% 2 3 3 2 3 4 3 7% 53%	2470
	21st to end	Night	14% 4 2 4 3 2 4 4 6% 6% 50%	2470
December	1st to 10th	Night	18% 7% 3 5% 4 3 3 4 5% 5% 43%	2470
	11th to 20th	Night	15% 6% 2 4 3 3 4 4 4 5% 50%	3042
	21st to end	Night	20% 6% 2 5% 4 3 5% 4 5% 6% 40%	4532

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	32% 3 6% 25% 27% 7%	2837
	11th to 20th	Day	35% 4 6% 17% 31% 6%	2840
	21st to end	Day	41% 4 6% 19% 26% 5%	3124
February	1st to 10th	Day	39% 5% 11% 21% 19% 5%	1729
	11th to 20th	Day	41% 5% 9% 20% 19% 6%	1858
	21st to end	Day	44% 5% 9% 16% 18% 8%	1570
March	1st to 10th	Day	35% 4 8% 21% 24% 8%	2030
	11th to 20th	Day	44% 6% 10% 16% 17% 6%	1980
	21st to end	Day	43% 6% 12% 21% 16% 3	2178
April	1st to 10th	Day	31% 6% 12% 23% 23% 6%	1980
	11th to 20th	Day	36% 5% 10% 20% 22% 7%	2132
	21st to end	Day	37% 7% 12% 25% 16% 4	2340
May	1st to 10th	Day	36% 9% 16% 22% 15% 3	2340
	11th to 20th	Day	43% 10% 15% 19% 11% 2	2305
	21st to end	Day	38% 9% 16% 25% 11% 1	2531
June	1st to 10th	Day	40% 11% 17% 22% 10% 1	2340
	11th to 20th	Day	37% 11% 17% 19% 13% 2	2340
	21st to end	Day	37% 13% 16% 18% 14% 2	2340
July	1st to 10th	Day	43% 13% 16% 15% 11% 3	2275
	11th to 20th	Day	42% 13% 19% 15% 10% 1	2271
	21st to end	Day	39% 14% 19% 18% 8% 2	2405
August	1st to 10th	Day	47% 13% 16% 17% 6%	2314
	11th to 20th	Day	46% 12% 17% 16% 7% 1	2303
	21st to end	Day	41% 10% 17% 22% 8% 3	2427
September	1st to 10th	Day	39% 8% 15% 21% 14% 4	1980
	11th to 20th	Day	42% 8% 10% 19% 17% 3	1980
	21st to end	Day	43% 7% 9% 19% 17% 5%	1980
October	1st to 10th	Day	33% 5% 10% 20% 27% 5%	1906
	11th to 20th	Day	31% 5% 9% 26% 21% 8%	1800
	21st to end	Day	32% 3 7% 24% 24% 9%	1980
November	1st to 10th	Day	29% 4 9% 21% 30% 8%	1826
	11th to 20th	Day	31% 3 8% 23% 26% 8%	1710
	21st to end	Day	33% 4 9% 24% 26% 6%	1710
December	1st to 10th	Day	45% 5% 8% 21% 16% 5%	1710
	11th to 20th	Day	31% 5% 8% 22% 24% 10%	2150
	21st to end	Day	39% 6% 8% 24% 19% 4	3124
January	1st to 10th	Night	33% 6% 8% 21% 26% 6%	4109
	11th to 20th	Night	34% 5% 7% 18% 29% 7%	4120
	21st to end	Night	44% 6% 5% 17% 22% 6%	4532
February	1st to 10th	Night	37% 5% 11% 22% 20% 4	2447
	11th to 20th	Night	42% 4 8% 19% 21% 6%	2219
	21st to end	Night	42% 6% 11% 17% 19% 6%	1884
March	1st to 10th	Night	36% 6% 8% 19% 23% 9%	2046
	11th to 20th	Night	42% 6% 10% 21% 18% 4	1980
	21st to end	Night	43% 6% 9% 22% 16% 4	2178
April	1st to 10th	Night	34% 6% 11% 22% 23% 5%	1980
	11th to 20th	Night	34% 6% 10% 23% 21% 7%	1791
	21st to end	Night	34% 6% 12% 25% 19% 4	1620
May	1st to 10th	Night	39% 7% 14% 25% 14% 2	1620
	11th to 20th	Night	45% 10% 12% 19% 12% 1	1593
	21st to end	Night	39% 10% 14% 24% 11% 1	1745
June	1st to 10th	Night	38% 13% 18% 21% 10% 1	1620
	11th to 20th	Night	37% 9% 20% 22% 10% 1	1620
	21st to end	Night	34% 13% 17% 20% 12% 4	1620
July	1st to 10th	Night	41% 13% 18% 17% 9% 3	1575
	11th to 20th	Night	40% 14% 20% 17% 7% 2	1566
	21st to end	Night	36% 13% 23% 20% 7% 1	1672
August	1st to 10th	Night	43% 13% 20% 17% 7%	1600
	11th to 20th	Night	42% 12% 17% 17% 10% 1	1598
	21st to end	Night	41% 12% 16% 21% 9% 2	1906
September	1st to 10th	Night	38% 10% 14% 20% 14% 4	1980
	11th to 20th	Night	44% 10% 11% 18% 17% 1	1980
	21st to end	Night	43% 6% 11% 18% 18% 4	1980
October	1st to 10th	Night	36% 7% 9% 20% 24% 4	2052
	11th to 20th	Night	34% 6% 8% 25% 20% 7%	2160
	21st to end	Night	31% 4 6% 21% 28% 10%	2376
November	1st to 10th	Night	34% 5% 7% 20% 26% 9%	2249
	11th to 20th	Night	32% 4 8% 20% 25% 10%	2470
	21st to end	Night	33% 5% 7% 23% 26% 6%	2470
December	1st to 10th	Night	42% 5% 9% 19% 19% 5%	2470
	11th to 20th	Night	35% 4 9% 18% 27% 7%	3044
	21st to end	Night	42% 6% 10% 23% 17% 2	4532

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% 17% 32% 22% 4	270
	11th to 20th	Day	24% 18% 34% 20% 3	270
	21st to end	Day	22% 21% 36% 18% 3	297
February	1st to 10th	Day	22% 17% 36% 19% 6%	270
	11th to 20th	Day	35% 21% 29% 13% 1	270
	21st to end	Day	31% 24% 33% 10% 3	225
March	1st to 10th	Day	19% 17% 29% 25% 9% 1	435
	11th to 20th	Day	24% 17% 30% 24% 4 1	420
	21st to end	Day	24% 14% 32% 23% 7%	462
April	1st to 10th	Day	19% 14% 30% 21% 13% 2	420
	11th to 20th	Day	18% 14% 26% 24% 15% 3	412
	21st to end	Day	17% 10% 27% 24% 15% 7%	420
May	1st to 10th	Day	14% 13% 28% 26% 13% 5%	423
	11th to 20th	Day	19% 6% 17% 29% 19% 10%	447
	21st to end	Day	18% 4 13% 27% 24% 15%	485
June	1st to 10th	Day	11% 5% 12% 35% 24% 12%	450
	11th to 20th	Day	10% 4 17% 26% 25% 18%	450
	21st to end	Day	9% 2 16% 33% 26% 14%	450
July	1st to 10th	Day	9% 2 10% 24% 30% 25%	445
	11th to 20th	Day	8% 2 10% 28% 29% 24%	444
	21st to end	Day	7% 2 9% 27% 30% 25%	488
August	1st to 10th	Day	16% 2 15% 22% 24% 22%	446
	11th to 20th	Day	12% 3 11% 23% 31% 20%	439
	21st to end	Day	13% 2 10% 21% 30% 25%	495
September	1st to 10th	Day	14% 3 8% 24% 32% 20%	450
	11th to 20th	Day	19% 4 12% 19% 30% 16%	450
	21st to end	Day	22% 3 16% 26% 26% 7%	450
October	1st to 10th	Day	21% 4 15% 26% 24% 11%	450
	11th to 20th	Day	15% 9% 19% 30% 20% 6%	450
	21st to end	Day	18% 8% 19% 34% 18% 4	495
November	1st to 10th	Day	21% 6% 21% 30% 17% 5%	424
	11th to 20th	Day	17% 14% 34% 25% 9% 2	270
	21st to end	Day	13% 13% 33% 29% 11% 2	270
December	1st to 10th	Day	27% 16% 29% 22% 6%	270
	11th to 20th	Day	19% 14% 29% 28% 9% 1	270
	21st to end	Day	25% 12% 35% 20% 6% 2	297
January	1st to 10th	Night	19% 12% 30% 32% 7%	760
	11th to 20th	Night	19% 9% 33% 33% 5%	760
	21st to end	Night	16% 11% 35% 33% 4	836
February	1st to 10th	Night	17% 8% 33% 38% 4	760
	11th to 20th	Night	23% 12% 36% 27% 2	743
	21st to end	Night	18% 15% 33% 30% 3	628
March	1st to 10th	Night	18% 8% 31% 38% 5%	743
	11th to 20th	Night	18% 12% 30% 31% 9% 1	720
	21st to end	Night	19% 9% 32% 31% 9%	792
April	1st to 10th	Night	16% 10% 30% 34% 10%	720
	11th to 20th	Night	16% 12% 26% 31% 15% 1	686
	21st to end	Night	16% 5% 21% 40% 17%	540
May	1st to 10th	Night	14% 5% 23% 39% 18% 1	540
	11th to 20th	Night	15% 4 17% 35% 26% 3	531
	21st to end	Night	16% 2 9% 31% 36% 7%	584
June	1st to 10th	Night	10% 3 11% 33% 37% 6%	540
	11th to 20th	Night	11% 2 9% 31% 36% 10%	540
	21st to end	Night	9% 1 6% 34% 43% 7%	540
July	1st to 10th	Night	11% 2 7% 22% 49% 9%	525
	11th to 20th	Night	12% 2 5% 23% 47% 12%	522
	21st to end	Night	6% 2 5% 26% 48% 13%	591
August	1st to 10th	Night	16% 2 4 24% 44% 9%	537
	11th to 20th	Night	13% 3 6% 26% 42% 11%	534
	21st to end	Night	12% 2 8% 23% 43% 12%	683
September	1st to 10th	Night	12% 2 8% 26% 41% 11%	720
	11th to 20th	Night	18% 3 8% 24% 39% 8%	720
	21st to end	Night	21% 2 13% 30% 30% 3	720
October	1st to 10th	Night	19% 5% 14% 27% 28% 7%	720
	11th to 20th	Night	18% 5% 22% 34% 19% 3	720
	21st to end	Night	16% 7% 18% 40% 17% 3	792
November	1st to 10th	Night	16% 6% 18% 40% 17% 3	740
	11th to 20th	Night	15% 7% 25% 39% 12% 1	760
	21st to end	Night	16% 7% 24% 36% 16% 1	760
December	1st to 10th	Night	21% 9% 25% 36% 8%	760
	11th to 20th	Night	18% 7% 29% 37% 8% 1	760
	21st to end	Night	25% 10% 24% 35% 7%	836

Page generated at 2024-03-03 06:29:00. Version ac07

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