Red Oak observing site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Red Oak observing site 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	13% 7% 3 5% 5% 3 4 4 5% 7% 44%	78623
	Night	12% 7% 3 5% 4 3 4 4 4 7% 48%	80926
Transparency	Day	40% 6% 11% 24% 16% 3	78346
	Night	37% 5% 10% 24% 19% 4	80723
Seeing	Day	15% 8% 26% 28% 18% 6%	14540
	Night	15% 9% 31% 31% 13% 1	24582

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	15% 11% 3 4 5% 3 3 3 3 5% 43%	2847
	11th to 20th	Day	11% 10% 5% 6% 6% 2 4 4 4 6% 43%	2850
	21st to end	Day	21% 12% 3 6% 3 2 3 2 4 4 40%	3135
February	1st to 10th	Day	15% 11% 3 6% 6% 3 4 4 4 4 39%	1710
	11th to 20th	Day	13% 9% 4 7% 5% 2 4 3 5% 5% 43%	1664
	21st to end	Day	17% 9% 3 6% 5% 2 4 4 5% 6% 40%	1673
March	1st to 10th	Day	13% 8% 3 6% 4 2 3 4 5% 6% 45%	2035
	11th to 20th	Day	22% 9% 4 5% 4 2 4 4 4 4 38%	1980
	21st to end	Day	20% 10% 4 7% 5% 3 4 4 5% 6% 32%	2178
April	1st to 10th	Day	11% 7% 3 6% 5% 3 3 5% 5% 8% 44%	2096
	11th to 20th	Day	17% 8% 3 5% 5% 3 5% 4 5% 7% 39%	2134
	21st to end	Day	21% 7% 3 5% 5% 3 5% 4 5% 5% 37%	2179
May	1st to 10th	Day	20% 7% 3 6% 5% 2 4 4 5% 6% 38%	2340
	11th to 20th	Day	15% 6% 3 6% 6% 4 5% 5% 5% 8% 40%	2302
	21st to end	Day	12% 6% 3 6% 7% 4 7% 5% 7% 9% 35%	2531
June	1st to 10th	Day	7% 4 2 5% 5% 3 5% 6% 6% 9% 47%	2474
	11th to 20th	Day	8% 4 2 5% 4 3 6% 5% 6% 10% 47%	2520
	21st to end	Day	6% 2 1 3 4 2 4 5% 6% 10% 57%	2389
July	1st to 10th	Day	10% 4 3 6% 5% 4 6% 5% 8% 10% 40%	2340
	11th to 20th	Day	4 3 2 4 5% 3 5% 6% 7% 9% 53%	2340
	21st to end	Day	9% 5% 2 5% 5% 3 6% 6% 7% 10% 43%	2546
August	1st to 10th	Day	8% 4 2 5% 5% 3 6% 5% 8% 10% 44%	2328
	11th to 20th	Day	8% 5% 2 5% 6% 4 6% 5% 7% 9% 44%	2286
	21st to end	Day	7% 4 2 5% 4 3 4 5% 5% 8% 52%	2376
September	1st to 10th	Day	13% 5% 2 5% 4 2 4 4 4 6% 52%	2160
	11th to 20th	Day	11% 6% 2 5% 4 3 4 4 6% 7% 48%	2037
	21st to end	Day	8% 4 2 4 5% 3 4 5% 5% 7% 54%	1943
October	1st to 10th	Day	11% 4 2 4 4 3 4 4 4 7% 53%	1800
	11th to 20th	Day	14% 5% 2 5% 3 2 3 3 4 6% 54%	1800
	21st to end	Day	19% 7% 2 4 3 2 3 3 3 5% 48%	1980
November	1st to 10th	Day	11% 5% 2 5% 3 1 3 3 4 6% 57%	1858
	11th to 20th	Day	14% 7% 2 4 3 2 3 3 5% 6% 52%	1792
	21st to end	Day	15% 9% 3 4 4 2 2 3 3 7% 49%	1520
December	1st to 10th	Day	13% 8% 3 6% 6% 3 3 4 4 6% 45%	1520
	11th to 20th	Day	13% 11% 4 6% 5% 3 3 2 3 6% 43%	1918
	21st to end	Day	15% 18% 5% 8% 6% 2 4 4 4 5% 28%	3042
January	1st to 10th	Night	11% 9% 4 9% 5% 3 3 3 4 5% 44%	4108
	11th to 20th	Night	11% 6% 3 6% 8% 3 5% 5% 4 5% 44%	4120
	21st to end	Night	22% 11% 4 6% 3 2 2 2 3 4 40%	4532
February	1st to 10th	Night	15% 10% 4 5% 4 2 3 4 5% 5% 43%	2470
	11th to 20th	Night	14% 8% 4 6% 3 2 3 4 3 6% 45%	2403
	21st to end	Night	15% 8% 3 5% 4 3 4 4 4 5% 45%	1794
March	1st to 10th	Night	14% 7% 2 5% 4 2 3 3 4 6% 48%	2041
	11th to 20th	Night	18% 8% 3 5% 5% 3 4 4 4 5% 42%	1980
	21st to end	Night	17% 8% 3 5% 5% 3 4 4 5% 7% 38%	2178
April	1st to 10th	Night	11% 5% 3 4 4 3 3 3 5% 7% 53%	1864
	11th to 20th	Night	13% 7% 2 5% 4 3 3 4 5% 7% 47%	1775
	21st to end	Night	17% 7% 3 5% 4 3 5% 4 5% 6% 41%	1778
May	1st to 10th	Night	14% 6% 2 5% 5% 2 4 4 5% 8% 44%	1620
	11th to 20th	Night	14% 6% 2 4 4 3 3 4 5% 7% 48%	1593
	21st to end	Night	9% 6% 4 6% 5% 3 4 5% 7% 10% 41%	1745
June	1st to 10th	Night	6% 3 2 4 4 3 4 5% 7% 10% 53%	1476
	11th to 20th	Night	5% 2 1 4 3 4 4 4 7% 10% 54%	1440
	21st to end	Night	3 2 2 3 3 2 4 3 6% 11% 61%	1561
July	1st to 10th	Night	7% 3 1 3 3 3 5% 6% 7% 12% 50%	1620
	11th to 20th	Night	4 2 2 3 4 2 5% 4 6% 9% 59%	1620
	21st to end	Night	6% 4 2 4 5% 2 4 6% 7% 10% 50%	1772
August	1st to 10th	Night	6% 4 2 3 5% 3 4 5% 7% 9% 53%	1611
	11th to 20th	Night	6% 3 1 3 4 3 3 4 5% 10% 57%	1613
	21st to end	Night	4 4 2 4 5% 3 4 4 5% 8% 57%	1980
September	1st to 10th	Night	10% 4 2 4 3 2 4 3 4 8% 56%	1800
	11th to 20th	Night	10% 5% 2 5% 5% 2 4 3 5% 8% 51%	1919
	21st to end	Night	8% 4 2 4 4 2 3 4 5% 7% 58%	1998
October	1st to 10th	Night	8% 4 2 4 2 2 3 3 4 7% 61%	2160
	11th to 20th	Night	15% 5% 1 3 3 2 3 4 4 6% 55%	2160
	21st to end	Night	16% 6% 3 4 3 2 2 3 3 5% 52%	2376
November	1st to 10th	Night	12% 4 2 3 3 1 2 3 3 5% 62%	2220
	11th to 20th	Night	12% 5% 3 4 4 2 3 4 3 5% 54%	2381
	21st to end	Night	16% 7% 2 4 4 2 3 3 3 5% 51%	2660
December	1st to 10th	Night	13% 8% 3 5% 5% 2 4 4 5% 7% 44%	2660
	11th to 20th	Night	15% 8% 4 6% 5% 3 3 3 4 5% 44%	3279
	21st to end	Night	16% 16% 5% 7% 5% 2 4 4 4 5% 32%	4619

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	45% 2 7% 25% 18% 1	2848
	11th to 20th	Day	43% 3 11% 27% 12% 4	2850
	21st to end	Day	49% 3 9% 19% 17% 3	3135
February	1st to 10th	Day	48% 4 11% 23% 12% 2	1710
	11th to 20th	Day	44% 4 10% 22% 16% 4	1673
	21st to end	Day	47% 3 6% 22% 15% 8%	1673
March	1st to 10th	Day	41% 4 9% 22% 19% 5%	2035
	11th to 20th	Day	51% 5% 8% 19% 14% 3	1980
	21st to end	Day	54% 5% 11% 20% 9% 1	2178
April	1st to 10th	Day	39% 5% 11% 25% 18% 1	2096
	11th to 20th	Day	45% 5% 13% 20% 15% 2	2134
	21st to end	Day	50% 5% 9% 24% 11% 1	2179
May	1st to 10th	Day	47% 5% 12% 22% 13% 1	2340
	11th to 20th	Day	41% 8% 13% 24% 13% 1	2306
	21st to end	Day	44% 10% 14% 22% 10%	2531
June	1st to 10th	Day	32% 8% 15% 28% 15% 1	2474
	11th to 20th	Day	32% 7% 14% 29% 16% 2	2520
	21st to end	Day	23% 7% 16% 31% 19% 4	2389
July	1st to 10th	Day	35% 9% 16% 25% 14% 2	2276
	11th to 20th	Day	25% 10% 13% 29% 20% 3	2271
	21st to end	Day	34% 8% 15% 31% 12% 1	2405
August	1st to 10th	Day	34% 9% 15% 25% 15% 1	2314
	11th to 20th	Day	35% 8% 10% 29% 16% 1	2286
	21st to end	Day	30% 6% 11% 26% 20% 7%	2376
September	1st to 10th	Day	34% 5% 12% 26% 16% 7%	2160
	11th to 20th	Day	35% 6% 9% 23% 25% 2	2037
	21st to end	Day	29% 8% 9% 26% 23% 5%	1943
October	1st to 10th	Day	31% 4 11% 26% 23% 5%	1800
	11th to 20th	Day	33% 4 8% 26% 23% 7%	1800
	21st to end	Day	41% 3 8% 24% 19% 6%	1980
November	1st to 10th	Day	29% 4 10% 29% 22% 6%	1858
	11th to 20th	Day	36% 4 8% 22% 24% 7%	1792
	21st to end	Day	38% 5% 8% 23% 24% 2	1520
December	1st to 10th	Day	41% 4 7% 31% 15% 1	1520
	11th to 20th	Day	45% 3 8% 19% 23% 3	1915
	21st to end	Day	58% 5% 8% 17% 11% 1	3042
January	1st to 10th	Night	45% 3 9% 26% 16% 2	4108
	11th to 20th	Night	42% 4 11% 26% 15% 2	4120
	21st to end	Night	50% 3 10% 19% 16% 2	4532
February	1st to 10th	Night	43% 4 11% 23% 15% 3	2470
	11th to 20th	Night	42% 3 9% 24% 18% 4	2404
	21st to end	Night	42% 3 9% 21% 19% 6%	1794
March	1st to 10th	Night	39% 3 9% 20% 21% 7%	2041
	11th to 20th	Night	46% 5% 9% 18% 19% 3	1980
	21st to end	Night	46% 6% 10% 23% 13% 2	2178
April	1st to 10th	Night	32% 4 13% 24% 21% 5%	1864
	11th to 20th	Night	37% 5% 10% 23% 20% 5%	1775
	21st to end	Night	43% 6% 11% 22% 18% 1	1778
May	1st to 10th	Night	38% 7% 14% 23% 17% 2	1620
	11th to 20th	Night	36% 7% 14% 25% 16% 2	1594
	21st to end	Night	37% 9% 15% 27% 11% 1	1746
June	1st to 10th	Night	25% 7% 17% 31% 17% 3	1476
	11th to 20th	Night	25% 7% 15% 30% 21% 3	1440
	21st to end	Night	19% 5% 16% 34% 21% 5%	1561
July	1st to 10th	Night	23% 8% 17% 30% 19% 3	1575
	11th to 20th	Night	21% 5% 13% 31% 27% 3	1566
	21st to end	Night	26% 7% 13% 35% 18% 1	1673
August	1st to 10th	Night	26% 7% 16% 33% 16% 1	1601
	11th to 20th	Night	23% 6% 12% 29% 26% 2	1613
	21st to end	Night	24% 7% 13% 24% 24% 7%	1980
September	1st to 10th	Night	29% 5% 10% 27% 20% 8%	1800
	11th to 20th	Night	32% 5% 9% 22% 26% 5%	1919
	21st to end	Night	26% 5% 9% 25% 30% 4	1998
October	1st to 10th	Night	25% 4 10% 26% 27% 7%	2160
	11th to 20th	Night	33% 4 6% 25% 26% 7%	2160
	21st to end	Night	37% 4 7% 23% 23% 7%	2376
November	1st to 10th	Night	28% 3 9% 26% 26% 8%	2220
	11th to 20th	Night	34% 3 6% 25% 26% 6%	2381
	21st to end	Night	38% 4 8% 23% 24% 4	2660
December	1st to 10th	Night	41% 4 10% 24% 19% 2	2660
	11th to 20th	Night	45% 3 7% 22% 21% 2	3281
	21st to end	Night	55% 5% 9% 18% 10% 3	4619

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	19% 16% 36% 23% 5%	270
	11th to 20th	Day	26% 17% 39% 16% 2	270
	21st to end	Day	19% 12% 47% 16% 5%	297
February	1st to 10th	Day	22% 17% 40% 17% 3	270
	11th to 20th	Day	21% 20% 42% 14% 4	270
	21st to end	Day	28% 20% 36% 14% 3	225
March	1st to 10th	Day	22% 15% 37% 22% 4	255
	11th to 20th	Day	30% 14% 32% 22% 3	240
	21st to end	Day	27% 19% 41% 10% 4	264
April	1st to 10th	Day	15% 19% 38% 24% 4 1	356
	11th to 20th	Day	20% 16% 37% 20% 7%	412
	21st to end	Day	25% 12% 32% 23% 6% 1	439
May	1st to 10th	Day	20% 12% 33% 26% 8% 1	603
	11th to 20th	Day	16% 9% 32% 27% 13% 3	625
	21st to end	Day	13% 6% 28% 26% 18% 8%	679
June	1st to 10th	Day	7% 3 18% 34% 27% 10%	630
	11th to 20th	Day	8% 2 19% 37% 26% 8%	630
	21st to end	Day	5% 3 26% 37% 24% 5%	630
July	1st to 10th	Day	11% 1 13% 31% 30% 14%	621
	11th to 20th	Day	4 2 14% 35% 34% 11%	618
	21st to end	Day	9% 2 10% 31% 33% 14%	684
August	1st to 10th	Day	9% 2 12% 41% 29% 7%	626
	11th to 20th	Day	9% 2 13% 36% 32% 9%	600
	21st to end	Day	11% 1 9% 28% 37% 14%	495
September	1st to 10th	Day	11% 1 10% 35% 32% 10%	450
	11th to 20th	Day	6% 3 12% 37% 30% 12%	327
	21st to end	Day	10% 6% 17% 36% 22% 8%	270
October	1st to 10th	Day	13% 6% 26% 32% 18% 6%	270
	11th to 20th	Day	16% 11% 38% 28% 7% 1	270
	21st to end	Day	29% 10% 30% 25% 4 2	297
November	1st to 10th	Day	15% 9% 38% 24% 11% 2	270
	11th to 20th	Day	16% 17% 36% 22% 8% 2	270
	21st to end	Day	24% 13% 34% 21% 7%	270
December	1st to 10th	Day	17% 12% 43% 16% 10% 1	270
	11th to 20th	Day	21% 12% 41% 17% 7% 1	270
	21st to end	Day	18% 22% 38% 20% 3	297
January	1st to 10th	Night	17% 15% 38% 24% 5%	950
	11th to 20th	Night	18% 15% 41% 21% 4 1	950
	21st to end	Night	18% 14% 40% 24% 3	1045
February	1st to 10th	Night	21% 13% 42% 21% 3	950
	11th to 20th	Night	19% 16% 42% 22% 2	929
	21st to end	Night	22% 19% 36% 21% 2	538
March	1st to 10th	Night	18% 12% 41% 25% 4	557
	11th to 20th	Night	22% 13% 37% 24% 4	540
	21st to end	Night	22% 12% 40% 21% 4 1	594
April	1st to 10th	Night	13% 13% 38% 31% 4	540
	11th to 20th	Night	17% 11% 34% 31% 7%	533
	21st to end	Night	20% 10% 40% 22% 7% 1	540
May	1st to 10th	Night	14% 6% 37% 34% 8%	540
	11th to 20th	Night	16% 4 28% 35% 16% 2	531
	21st to end	Night	11% 4 29% 35% 20% 1	584
June	1st to 10th	Night	7% 2 16% 42% 30% 1	540
	11th to 20th	Night	6% 2 24% 43% 25% 1	540
	21st to end	Night	3 3 22% 51% 21% 1	540
July	1st to 10th	Night	6% 1 13% 39% 37% 5%	525
	11th to 20th	Night	3 2 11% 45% 35% 4	522
	21st to end	Night	7% 2 9% 44% 35% 4	591
August	1st to 10th	Night	6% 1 12% 46% 33% 2	537
	11th to 20th	Night	5% 2 12% 48% 29% 4	534
	21st to end	Night	4 1 13% 40% 38% 5%	594
September	1st to 10th	Night	11% 1 12% 44% 30% 2	540
	11th to 20th	Night	11% 2 13% 43% 29% 3	540
	21st to end	Night	10% 3 19% 43% 21% 4	558
October	1st to 10th	Night	10% 3 27% 37% 20% 3	720
	11th to 20th	Night	17% 6% 38% 30% 8% 1	720
	21st to end	Night	20% 10% 31% 29% 10% 1	792
November	1st to 10th	Night	14% 7% 41% 27% 10% 1	740
	11th to 20th	Night	14% 13% 38% 27% 7%	833
	21st to end	Night	21% 11% 36% 24% 7%	950
December	1st to 10th	Night	18% 13% 39% 25% 5%	950
	11th to 20th	Night	22% 12% 34% 28% 4	950
	21st to end	Night	20% 14% 39% 24% 3	1045

Page generated at 2024-03-03 05:28:56. Version ac07

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