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 2024-11-01.

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	12% 7% 2 6% 4 4 4 3 5% 7% 45%	100832
	Night	12% 7% 2 6% 4 3 3 3 5% 7% 49%	98186
Transparency	Day	38% 6% 12% 25% 16% 3	100644
	Night	36% 5% 11% 26% 19% 4	98045
Seeing	Day	14% 8% 26% 28% 18% 5%	15536
	Night	15% 9% 31% 31% 13% 1	25335

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 5% 4 4 3 2 4 5% 43%	2847
	11th to 20th	Day	10% 10% 4 7% 6% 3 4 3 4 6% 43%	2850
	21st to end	Day	21% 12% 3 7% 3 2 2 2 4 4 39%	3135
February	1st to 10th	Day	15% 12% 3 7% 5% 3 4 4 4 4 39%	1710
	11th to 20th	Day	13% 10% 3 8% 4 3 3 3 5% 5% 43%	1664
	21st to end	Day	16% 9% 2 7% 5% 3 3 3 5% 6% 39%	1673
March	1st to 10th	Day	15% 8% 2 6% 3 3 3 3 4 5% 48%	3436
	11th to 20th	Day	14% 7% 2 4 3 3 3 3 4 6% 50%	3480
	21st to end	Day	17% 11% 4 7% 5% 4 4 3 5% 6% 34%	3814
April	1st to 10th	Day	11% 8% 2 6% 4 5% 3 4 5% 8% 44%	2213
	11th to 20th	Day	16% 9% 2 6% 4 4 4 3 5% 6% 40%	2254
	21st to end	Day	21% 8% 3 6% 4 4 4 4 5% 5% 37%	2301
May	1st to 10th	Day	20% 8% 2 7% 4 3 4 4 5% 6% 35%	4082
	11th to 20th	Day	14% 6% 3 7% 4 5% 5% 4 5% 8% 40%	4082
	21st to end	Day	14% 6% 2 6% 6% 5% 5% 4 6% 8% 38%	4477
June	1st to 10th	Day	7% 5% 2 6% 4 4 6% 4 6% 9% 46%	2612
	11th to 20th	Day	8% 4 2 5% 4 4 6% 3 6% 9% 48%	2660
	21st to end	Day	6% 2 1 4 3 4 4 4 6% 10% 56%	2521
July	1st to 10th	Day	11% 5% 3 6% 4 5% 5% 4 7% 9% 42%	4120
	11th to 20th	Day	5% 4 1 5% 4 4 5% 5% 6% 9% 50%	4120
	21st to end	Day	7% 4 1 5% 4 5% 6% 5% 8% 11% 44%	4465
August	1st to 10th	Day	5% 3 1 4 3 3 4 3 6% 9% 57%	4104
	11th to 20th	Day	8% 5% 2 7% 4 5% 6% 4 7% 8% 44%	4012
	21st to end	Day	6% 3 2 4 3 4 4 4 5% 8% 57%	4180
September	1st to 10th	Day	12% 5% 2 5% 4 3 3 3 4 5% 54%	2280
	11th to 20th	Day	10% 7% 2 6% 4 5% 4 3 6% 7% 47%	2150
	21st to end	Day	8% 5% 2 5% 4 4 4 4 5% 7% 53%	2050
October	1st to 10th	Day	11% 4 2 4 3 4 3 3 5% 6% 55%	1900
	11th to 20th	Day	14% 5% 2 5% 2 2 3 2 4 6% 55%	1900
	21st to end	Day	18% 7% 2 4 3 3 3 2 4 5% 49%	2090
November	1st to 10th	Day	11% 5% 2 6% 2 2 3 2 4 6% 57%	1858
	11th to 20th	Day	14% 7% 2 4 3 3 3 2 5% 5% 51%	1792
	21st to end	Day	15% 9% 2 4 4 2 3 2 3 7% 49%	1520
December	1st to 10th	Day	13% 8% 3 7% 4 4 3 4 5% 6% 45%	1520
	11th to 20th	Day	12% 12% 3 7% 5% 4 3 2 4 6% 43%	1918
	21st to end	Day	15% 18% 5% 9% 4 4 4 3 5% 5% 28%	3042
January	1st to 10th	Night	11% 10% 4 10% 4 3 3 2 4 5% 44%	4108
	11th to 20th	Night	10% 7% 3 7% 6% 5% 5% 3 4 5% 44%	4120
	21st to end	Night	22% 12% 4 6% 3 2 2 2 4 4 40%	4532
February	1st to 10th	Night	15% 11% 3 6% 4 3 3 3 5% 5% 42%	2470
	11th to 20th	Night	14% 9% 3 6% 3 3 3 3 4 6% 45%	2403
	21st to end	Night	14% 8% 3 6% 4 4 3 3 4 5% 45%	1794
March	1st to 10th	Night	15% 8% 2 6% 4 3 3 3 4 5% 47%	3419
	11th to 20th	Night	12% 6% 2 4 4 4 3 3 4 5% 52%	3480
	21st to end	Night	13% 7% 3 7% 5% 4 4 4 5% 6% 41%	3817
April	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 5% 7% 52%	1967
	11th to 20th	Night	13% 8% 2 6% 3 3 3 3 5% 7% 47%	1875
	21st to end	Night	17% 8% 3 6% 3 4 4 3 5% 5% 41%	1876
May	1st to 10th	Night	13% 8% 2 5% 4 3 4 3 5% 8% 44%	2823
	11th to 20th	Night	14% 7% 3 6% 4 4 4 3 5% 8% 42%	2823
	21st to end	Night	10% 6% 3 6% 4 4 3 4 6% 9% 45%	3090
June	1st to 10th	Night	6% 4 2 4 4 4 4 4 7% 9% 52%	1558
	11th to 20th	Night	5% 3 1 4 3 4 4 3 7% 10% 55%	1520
	21st to end	Night	4 3 1 3 3 3 3 2 7% 10% 60%	1648
July	1st to 10th	Night	10% 4 2 5% 3 4 4 4 6% 9% 49%	2850
	11th to 20th	Night	3 2 1 4 3 4 4 3 5% 9% 60%	2850
	21st to end	Night	6% 4 2 4 4 3 3 4 6% 11% 53%	3098
August	1st to 10th	Night	3 3 1 3 3 3 4 4 6% 8% 63%	2836
	11th to 20th	Night	9% 4 1 5% 4 4 4 4 6% 8% 51%	2824
	21st to end	Night	3 3 2 4 3 3 3 3 5% 8% 62%	3476
September	1st to 10th	Night	9% 4 2 4 3 3 4 3 4 7% 56%	1900
	11th to 20th	Night	10% 5% 2 7% 4 3 4 2 5% 8% 52%	2026
	21st to end	Night	8% 4 2 5% 4 3 4 3 5% 6% 57%	2109
October	1st to 10th	Night	8% 4 1 4 2 2 3 2 4 7% 62%	2280
	11th to 20th	Night	14% 5% 1 4 3 2 3 3 4 5% 57%	2280
	21st to end	Night	16% 6% 2 4 3 3 2 2 4 5% 52%	2508
November	1st to 10th	Night	12% 5% 2 4 2 2 3 2 3 5% 62%	2227
	11th to 20th	Night	12% 6% 2 5% 4 2 3 3 4 5% 54%	2381
	21st to end	Night	15% 8% 2 4 3 2 3 2 4 5% 51%	2660
December	1st to 10th	Night	13% 9% 3 5% 4 3 4 3 5% 6% 44%	2660
	11th to 20th	Night	15% 8% 4 7% 4 4 3 2 4 5% 43%	3279
	21st to end	Night	16% 16% 5% 8% 4 3 4 3 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	39% 4 7% 23% 20% 7%	3436
	11th to 20th	Day	35% 5% 11% 27% 16% 6%	3480
	21st to end	Day	50% 6% 13% 22% 8% 1	3814
April	1st to 10th	Day	40% 5% 11% 24% 18% 2	2213
	11th to 20th	Day	44% 5% 13% 19% 17% 2	2254
	21st to end	Day	49% 5% 9% 24% 12% 1	2301
May	1st to 10th	Day	48% 7% 10% 20% 13% 1	4120
	11th to 20th	Day	40% 9% 13% 25% 13%	4086
	21st to end	Day	42% 8% 14% 23% 13% 1	4489
June	1st to 10th	Day	32% 9% 15% 28% 15% 1	2612
	11th to 20th	Day	31% 6% 14% 30% 16% 2	2660
	21st to end	Day	23% 7% 16% 31% 18% 4	2521
July	1st to 10th	Day	36% 8% 16% 23% 15% 3	4056
	11th to 20th	Day	28% 8% 11% 35% 17% 2	4051
	21st to end	Day	29% 9% 23% 28% 10%	4325
August	1st to 10th	Day	25% 6% 17% 28% 24% 1	4090
	11th to 20th	Day	36% 7% 15% 27% 15% 1	4051
	21st to end	Day	26% 6% 11% 39% 15% 4	4179
September	1st to 10th	Day	33% 5% 11% 26% 16% 9%	2280
	11th to 20th	Day	35% 6% 10% 23% 24% 2	2150
	21st to end	Day	30% 8% 9% 26% 23% 4	2050
October	1st to 10th	Day	29% 3 11% 25% 26% 6%	1900
	11th to 20th	Day	32% 3 7% 26% 25% 7%	1900
	21st to end	Day	39% 3 8% 24% 20% 6%	2090
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	40% 5% 10% 19% 20% 7%	3419
	11th to 20th	Night	35% 5% 9% 26% 22% 3	3480
	21st to end	Night	42% 7% 13% 27% 10% 1	3817
April	1st to 10th	Night	33% 4 13% 23% 22% 6%	1967
	11th to 20th	Night	37% 5% 9% 22% 21% 6%	1875
	21st to end	Night	43% 6% 11% 22% 17% 1	1876
May	1st to 10th	Night	39% 7% 12% 22% 16% 4	2850
	11th to 20th	Night	40% 8% 12% 27% 13% 1	2824
	21st to end	Night	35% 9% 13% 30% 12%	3099
June	1st to 10th	Night	26% 7% 17% 30% 17% 4	1558
	11th to 20th	Night	24% 7% 15% 31% 22% 3	1520
	21st to end	Night	20% 5% 16% 33% 21% 5%	1648
July	1st to 10th	Night	31% 7% 16% 25% 17% 5%	2805
	11th to 20th	Night	20% 5% 12% 38% 24% 2	2796
	21st to end	Night	25% 7% 19% 35% 14%	2999
August	1st to 10th	Night	19% 6% 16% 33% 24% 2	2826
	11th to 20th	Night	30% 7% 15% 29% 19% 1	2851
	21st to end	Night	20% 6% 13% 37% 20% 4	3476
September	1st to 10th	Night	28% 5% 10% 27% 21% 9%	1900
	11th to 20th	Night	32% 5% 9% 23% 26% 5%	2026
	21st to end	Night	27% 5% 9% 25% 30% 4	2109
October	1st to 10th	Night	23% 4 10% 25% 29% 9%	2280
	11th to 20th	Night	31% 4 6% 24% 27% 9%	2280
	21st to end	Night	36% 4 7% 24% 23% 7%	2508
November	1st to 10th	Night	28% 3 9% 26% 26% 8%	2227
	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	23% 14% 36% 22% 4	270
	11th to 20th	Day	27% 16% 33% 21% 3	270
	21st to end	Day	26% 18% 40% 10% 5%	297
April	1st to 10th	Day	16% 20% 37% 23% 4 1	393
	11th to 20th	Day	20% 17% 38% 18% 6%	452
	21st to end	Day	25% 12% 32% 24% 6% 1	481
May	1st to 10th	Day	19% 13% 34% 26% 8% 1	653
	11th to 20th	Day	15% 9% 31% 27% 14% 4	675
	21st to end	Day	13% 7% 29% 26% 17% 7%	734
June	1st to 10th	Day	7% 4 19% 35% 26% 9%	680
	11th to 20th	Day	7% 2 18% 38% 26% 8%	680
	21st to end	Day	5% 3 26% 37% 24% 5%	680
July	1st to 10th	Day	12% 1 14% 32% 28% 13%	671
	11th to 20th	Day	4 2 14% 36% 34% 10%	668
	21st to end	Day	9% 2 11% 31% 33% 15%	739
August	1st to 10th	Day	9% 2 13% 40% 29% 7%	676
	11th to 20th	Day	9% 2 14% 37% 31% 8%	649
	21st to end	Day	10% 1 9% 29% 37% 13%	539
September	1st to 10th	Day	10% 1 11% 36% 31% 11%	490
	11th to 20th	Day	7% 3 14% 38% 27% 11%	360
	21st to end	Day	10% 6% 19% 36% 21% 8%	300
October	1st to 10th	Day	11% 5% 24% 32% 23% 5%	300
	11th to 20th	Day	14% 11% 36% 27% 11% 1	300
	21st to end	Day	26% 10% 32% 26% 4 2	330
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	19% 11% 42% 25% 4	570
	11th to 20th	Night	21% 13% 38% 24% 4	570
	21st to end	Night	21% 13% 39% 22% 4 1	627
April	1st to 10th	Night	13% 14% 38% 30% 4	570
	11th to 20th	Night	17% 12% 35% 30% 7%	563
	21st to end	Night	20% 10% 39% 23% 7% 1	570
May	1st to 10th	Night	15% 6% 38% 34% 8%	570
	11th to 20th	Night	15% 5% 28% 34% 16% 1	561
	21st to end	Night	11% 5% 29% 35% 19% 1	617
June	1st to 10th	Night	8% 2 17% 43% 29% 1	570
	11th to 20th	Night	6% 2 24% 44% 25% 1	570
	21st to end	Night	3 3 22% 51% 21% 1	570
July	1st to 10th	Night	7% 1 13% 39% 35% 4	555
	11th to 20th	Night	3 2 11% 46% 34% 3	552
	21st to end	Night	7% 1 9% 44% 34% 4	624
August	1st to 10th	Night	6% 1 11% 46% 33% 2	567
	11th to 20th	Night	6% 2 13% 47% 28% 4	564
	21st to end	Night	4 1 13% 40% 38% 4	627
September	1st to 10th	Night	11% 1 12% 44% 31% 2	570
	11th to 20th	Night	11% 2 13% 44% 28% 3	570
	21st to end	Night	10% 4 19% 43% 20% 4	589
October	1st to 10th	Night	9% 3 26% 38% 21% 3	760
	11th to 20th	Night	16% 6% 38% 31% 8% 1	760
	21st to end	Night	19% 10% 32% 29% 9%	836
November	1st to 10th	Night	14% 7% 41% 27% 10% 1	743
	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 2024-10-29 10:20:48. Version ac07

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