Waffelow Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waffelow Creek Observatory clear sky chart from 2005-11-06 to 2024-07-02.

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% 7% 2 6% 4 4 4 4 5% 7% 42%	89685
	Night	14% 6% 2 5% 3 3 4 3 5% 7% 47%	89528
Transparency	Day	41% 6% 9% 19% 18% 6%	89457
	Night	37% 5% 10% 19% 20% 8%	89361
Seeing	Day	15% 8% 23% 26% 21% 6%	14564
	Night	16% 8% 25% 31% 17% 2	24440

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% 11% 2 5% 3 3 3 3 4 4 43%	2847
	11th to 20th	Day	21% 6% 2 4 2 2 2 2 4 5% 49%	2850
	21st to end	Day	25% 8% 2 5% 3 2 2 2 3 5% 43%	3135
February	1st to 10th	Day	22% 9% 3 6% 4 4 3 3 3 6% 37%	1710
	11th to 20th	Day	20% 9% 3 6% 4 4 4 3 3 4 40%	1852
	21st to end	Day	22% 7% 3 7% 4 3 4 2 4 3 41%	1727
March	1st to 10th	Day	21% 14% 3 7% 4 4 4 2 4 5% 32%	3436
	11th to 20th	Day	21% 8% 3 6% 3 4 4 4 6% 7% 34%	3480
	21st to end	Day	18% 9% 3 7% 4 4 4 3 4 5% 39%	3814
April	1st to 10th	Day	14% 6% 3 8% 5% 4 4 3 5% 6% 42%	2128
	11th to 20th	Day	16% 7% 2 7% 5% 4 4 3 6% 7% 39%	2254
	21st to end	Day	12% 6% 3 7% 5% 5% 4 3 5% 7% 44%	2280
May	1st to 10th	Day	20% 8% 3 8% 5% 5% 5% 4 6% 7% 31%	3819
	11th to 20th	Day	15% 6% 2 6% 5% 4 4 3 4 6% 44%	4082
	21st to end	Day	12% 6% 3 7% 6% 5% 6% 5% 8% 9% 33%	4477
June	1st to 10th	Day	8% 5% 2 6% 6% 5% 6% 5% 7% 10% 39%	2470
	11th to 20th	Day	5% 4 2 5% 5% 5% 6% 5% 8% 11% 43%	2470
	21st to end	Day	6% 6% 2 7% 6% 5% 6% 5% 8% 10% 39%	2470
July	1st to 10th	Day	8% 6% 2 7% 6% 6% 7% 5% 8% 10% 34%	2354
	11th to 20th	Day	7% 4 2 6% 5% 5% 6% 5% 9% 11% 40%	2340
	21st to end	Day	6% 4 2 7% 7% 5% 5% 6% 7% 11% 39%	2546
August	1st to 10th	Day	4 3 1 5% 4 5% 6% 5% 7% 10% 49%	2328
	11th to 20th	Day	6% 5% 2 7% 5% 6% 6% 4 7% 11% 42%	2194
	21st to end	Day	9% 4 2 7% 6% 6% 7% 5% 8% 10% 36%	2376
September	1st to 10th	Day	7% 6% 2 6% 6% 5% 4 6% 6% 8% 44%	2093
	11th to 20th	Day	13% 5% 2 7% 5% 5% 4 3 6% 8% 40%	1980
	21st to end	Day	8% 5% 2 5% 4 4 4 5% 5% 6% 52%	1980
October	1st to 10th	Day	8% 3 1 4 3 3 4 4 6% 6% 59%	1810
	11th to 20th	Day	13% 6% 1 4 3 3 3 3 4 6% 53%	1800
	21st to end	Day	16% 5% 2 5% 3 2 2 2 3 5% 54%	1980
November	1st to 10th	Day	11% 6% 3 5% 4 4 4 4 5% 7% 49%	1858
	11th to 20th	Day	12% 5% 2 5% 4 3 3 3 4 5% 52%	1900
	21st to end	Day	18% 7% 2 6% 4 3 3 3 4 5% 45%	1839
December	1st to 10th	Day	17% 8% 3 5% 4 4 3 2 4 6% 44%	1710
	11th to 20th	Day	17% 8% 2 7% 4 4 4 3 4 5% 42%	2161
	21st to end	Day	16% 10% 3 8% 3 4 3 3 3 4 42%	3135
January	1st to 10th	Night	15% 7% 2 6% 3 3 3 2 4 5% 50%	4108
	11th to 20th	Night	20% 7% 2 5% 2 2 2 2 3 3 52%	4120
	21st to end	Night	24% 11% 2 5% 3 2 2 2 3 4 41%	4532
February	1st to 10th	Night	17% 8% 3 6% 3 3 4 3 5% 6% 43%	2470
	11th to 20th	Night	22% 9% 2 5% 4 3 2 2 3 4 45%	2227
	21st to end	Night	21% 8% 2 5% 3 3 4 2 4 5% 44%	1727
March	1st to 10th	Night	24% 10% 2 6% 3 3 3 3 5% 5% 35%	3419
	11th to 20th	Night	19% 8% 3 7% 4 4 4 3 5% 7% 36%	3480
	21st to end	Night	15% 6% 2 7% 5% 4 3 4 5% 6% 43%	3817
April	1st to 10th	Night	13% 5% 2 6% 5% 3 4 4 6% 7% 46%	2050
	11th to 20th	Night	14% 6% 1 6% 4 4 5% 3 5% 6% 44%	1875
	21st to end	Night	13% 6% 2 5% 3 3 3 3 4 7% 50%	1900
May	1st to 10th	Night	15% 9% 3 7% 5% 4 4 3 6% 8% 36%	3072
	11th to 20th	Night	15% 7% 3 6% 4 4 3 3 4 6% 45%	2823
	21st to end	Night	11% 6% 2 6% 5% 4 5% 4 7% 9% 41%	3090
June	1st to 10th	Night	5% 4 2 5% 3 3 4 5% 6% 10% 52%	1710
	11th to 20th	Night	3 2 1 4 3 3 4 4 6% 10% 60%	1710
	21st to end	Night	6% 4 1 5% 4 4 3 4 8% 10% 49%	1710
July	1st to 10th	Night	5% 5% 1 5% 5% 5% 6% 5% 7% 12% 43%	1634
	11th to 20th	Night	3 3 1 3 3 4 4 4 7% 11% 57%	1620
	21st to end	Night	5% 3 1 3 4 4 4 5% 7% 14% 49%	1772
August	1st to 10th	Night	3 1 1 3 3 3 4 4 6% 12% 61%	1611
	11th to 20th	Night	3 4 2 5% 3 4 6% 5% 8% 11% 49%	1706
	21st to end	Night	8% 4 1 6% 4 5% 6% 6% 8% 9% 45%	1980
September	1st to 10th	Night	6% 5% 2 6% 4 4 4 3 6% 10% 51%	1862
	11th to 20th	Night	11% 5% 2 5% 4 4 4 3 4 8% 50%	1980
	21st to end	Night	8% 3 2 4 3 4 3 3 5% 7% 58%	1980
October	1st to 10th	Night	5% 3 2 4 3 3 3 3 5% 6% 62%	2131
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 4 5% 58%	2160
	21st to end	Night	14% 5% 2 4 3 2 3 2 4 4 59%	2376
November	1st to 10th	Night	11% 5% 1 4 3 3 4 3 5% 7% 55%	2220
	11th to 20th	Night	11% 6% 2 5% 4 3 3 3 4 7% 53%	2280
	21st to end	Night	16% 8% 3 6% 3 3 3 3 5% 5% 46%	2338
December	1st to 10th	Night	17% 8% 2 5% 3 4 4 3 5% 6% 45%	2470
	11th to 20th	Night	16% 9% 3 5% 4 4 3 2 4 4 46%	3036
	21st to end	Night	16% 8% 2 5% 3 4 3 3 4 4 48%	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	45% 4 4 18% 25% 5%	2848
	11th to 20th	Day	39% 3 4 23% 26% 5%	2850
	21st to end	Day	47% 2 3 18% 20% 10%	3135
February	1st to 10th	Day	51% 4 4 14% 17% 10%	1710
	11th to 20th	Day	50% 4 4 15% 19% 8%	1862
	21st to end	Day	49% 3 6% 13% 18% 12%	1727
March	1st to 10th	Day	56% 5% 6% 12% 17% 5%	3436
	11th to 20th	Day	47% 6% 6% 19% 16% 5%	3480
	21st to end	Day	48% 5% 7% 16% 22% 3	3814
April	1st to 10th	Day	44% 5% 7% 19% 17% 8%	2128
	11th to 20th	Day	43% 5% 9% 16% 17% 8%	2254
	21st to end	Day	40% 5% 8% 18% 24% 5%	2280
May	1st to 10th	Day	50% 8% 10% 18% 10% 3	3854
	11th to 20th	Day	41% 6% 9% 19% 24% 2	4086
	21st to end	Day	44% 10% 12% 21% 11% 1	4489
June	1st to 10th	Day	38% 8% 14% 24% 15% 1	2470
	11th to 20th	Day	32% 9% 14% 26% 16% 3	2470
	21st to end	Day	37% 9% 13% 26% 13% 2	2470
July	1st to 10th	Day	41% 12% 17% 23% 8% 1	2290
	11th to 20th	Day	35% 8% 18% 25% 14%	2271
	21st to end	Day	35% 10% 19% 26% 10%	2405
August	1st to 10th	Day	27% 9% 18% 31% 14% 1	2314
	11th to 20th	Day	33% 8% 19% 26% 12% 2	2194
	21st to end	Day	40% 10% 15% 22% 11% 2	2376
September	1st to 10th	Day	35% 8% 13% 20% 15% 8%	2093
	11th to 20th	Day	41% 7% 12% 16% 18% 7%	1980
	21st to end	Day	31% 5% 10% 20% 22% 11%	1980
October	1st to 10th	Day	26% 6% 10% 21% 24% 14%	1810
	11th to 20th	Day	33% 5% 5% 17% 25% 15%	1800
	21st to end	Day	35% 4 4 16% 28% 14%	1980
November	1st to 10th	Day	36% 4 7% 18% 25% 10%	1858
	11th to 20th	Day	35% 4 6% 18% 26% 11%	1900
	21st to end	Day	43% 4 6% 17% 23% 7%	1839
December	1st to 10th	Day	42% 3 10% 17% 19% 8%	1710
	11th to 20th	Day	45% 3 6% 14% 23% 8%	2159
	21st to end	Day	47% 4 4 13% 25% 7%	3135
January	1st to 10th	Night	38% 3 5% 19% 28% 8%	4108
	11th to 20th	Night	39% 3 4 18% 26% 10%	4120
	21st to end	Night	49% 2 5% 16% 19% 10%	4532
February	1st to 10th	Night	43% 4 6% 15% 19% 13%	2470
	11th to 20th	Night	46% 3 5% 16% 21% 10%	2227
	21st to end	Night	45% 4 7% 13% 18% 14%	1727
March	1st to 10th	Night	51% 4 6% 15% 17% 7%	3419
	11th to 20th	Night	49% 7% 8% 14% 18% 6%	3480
	21st to end	Night	41% 6% 9% 14% 24% 5%	3817
April	1st to 10th	Night	38% 6% 9% 19% 17% 12%	2050
	11th to 20th	Night	40% 5% 10% 19% 16% 12%	1875
	21st to end	Night	36% 4 9% 19% 25% 7%	1900
May	1st to 10th	Night	45% 7% 11% 20% 14% 4	3102
	11th to 20th	Night	40% 6% 10% 19% 22% 3	2824
	21st to end	Night	37% 10% 16% 23% 13% 1	3099
June	1st to 10th	Night	27% 8% 16% 30% 18% 1	1710
	11th to 20th	Night	19% 7% 17% 34% 19% 5%	1710
	21st to end	Night	28% 7% 16% 28% 19% 2	1710
July	1st to 10th	Night	30% 10% 23% 27% 9% 1	1589
	11th to 20th	Night	20% 9% 29% 26% 16% 1	1566
	21st to end	Night	22% 11% 26% 29% 11% 1	1673
August	1st to 10th	Night	16% 7% 25% 36% 15% 2	1601
	11th to 20th	Night	25% 9% 21% 28% 14% 3	1706
	21st to end	Night	33% 10% 16% 25% 13% 3	1980
September	1st to 10th	Night	30% 7% 16% 22% 17% 9%	1862
	11th to 20th	Night	34% 8% 12% 20% 17% 8%	1980
	21st to end	Night	26% 5% 10% 22% 24% 12%	1980
October	1st to 10th	Night	23% 4 9% 25% 22% 16%	2131
	11th to 20th	Night	30% 3 6% 17% 28% 16%	2160
	21st to end	Night	31% 4 6% 16% 26% 18%	2376
November	1st to 10th	Night	30% 4 9% 19% 25% 12%	2220
	11th to 20th	Night	33% 4 9% 17% 24% 13%	2280
	21st to end	Night	41% 3 6% 17% 22% 10%	2338
December	1st to 10th	Night	42% 4 9% 18% 19% 9%	2470
	11th to 20th	Night	43% 3 5% 13% 22% 13%	3037
	21st to end	Night	41% 4 5% 14% 29% 7%	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	27% 18% 37% 14% 4	270
	11th to 20th	Day	33% 13% 33% 17% 3 1	270
	21st to end	Day	29% 21% 33% 14% 2	297
February	1st to 10th	Day	28% 20% 32% 17% 3	270
	11th to 20th	Day	39% 17% 31% 12%	270
	21st to end	Day	31% 27% 36% 5% 1	225
March	1st to 10th	Day	31% 17% 32% 17% 2	270
	11th to 20th	Day	23% 27% 33% 14% 2	270
	21st to end	Day	24% 18% 38% 17% 4	297
April	1st to 10th	Day	24% 16% 40% 17% 3	308
	11th to 20th	Day	25% 18% 26% 21% 8% 1	452
	21st to end	Day	17% 16% 35% 22% 8% 2	460
May	1st to 10th	Day	16% 12% 39% 25% 7% 1	491
	11th to 20th	Day	16% 7% 28% 30% 17% 1	675
	21st to end	Day	12% 10% 28% 31% 16% 4	734
June	1st to 10th	Day	9% 3 19% 35% 27% 9%	680
	11th to 20th	Day	6% 1 20% 43% 25% 5%	680
	21st to end	Day	8% 2 14% 35% 30% 11%	680
July	1st to 10th	Day	9% 1 11% 33% 36% 10%	627
	11th to 20th	Day	4 1 8% 31% 43% 13%	618
	21st to end	Day	5% 1 8% 35% 39% 12%	684
August	1st to 10th	Day	4 1 7% 28% 48% 13%	626
	11th to 20th	Day	6% 4 30% 45% 14%	508
	21st to end	Day	12% 2 9% 19% 37% 21%	495
September	1st to 10th	Day	8% 7% 26% 42% 17%	383
	11th to 20th	Day	8% 1 15% 32% 32% 12%	270
	21st to end	Day	10% 3 10% 36% 31% 10%	270
October	1st to 10th	Day	8% 3 24% 38% 20% 7%	270
	11th to 20th	Day	12% 8% 33% 29% 13% 5%	270
	21st to end	Day	26% 10% 30% 19% 12% 3	297
November	1st to 10th	Day	16% 5% 30% 32% 15% 1	270
	11th to 20th	Day	17% 13% 33% 28% 8% 1	270
	21st to end	Day	24% 14% 37% 18% 5% 2	270
December	1st to 10th	Day	20% 13% 37% 19% 7% 4	270
	11th to 20th	Day	26% 14% 33% 20% 6%	270
	21st to end	Day	24% 18% 37% 15% 4 1	297
January	1st to 10th	Night	23% 13% 31% 27% 5%	950
	11th to 20th	Night	26% 14% 29% 24% 7%	950
	21st to end	Night	25% 13% 33% 26% 4	1045
February	1st to 10th	Night	23% 14% 34% 26% 3	950
	11th to 20th	Night	28% 15% 31% 22% 4	752
	21st to end	Night	27% 17% 34% 20% 2	471
March	1st to 10th	Night	24% 12% 35% 24% 5%	570
	11th to 20th	Night	19% 15% 33% 28% 5%	570
	21st to end	Night	17% 12% 41% 23% 6%	627
April	1st to 10th	Night	17% 14% 39% 23% 7%	570
	11th to 20th	Night	20% 12% 34% 22% 11%	563
	21st to end	Night	16% 10% 38% 25% 10%	570
May	1st to 10th	Night	11% 11% 41% 28% 9%	570
	11th to 20th	Night	15% 6% 32% 31% 14% 1	561
	21st to end	Night	9% 5% 28% 35% 20% 3	617
June	1st to 10th	Night	7% 2 13% 42% 31% 5%	570
	11th to 20th	Night	3 2 17% 50% 25% 3	570
	21st to end	Night	7% 1 12% 43% 30% 6%	570
July	1st to 10th	Night	7% 11% 40% 35% 7%	530
	11th to 20th	Night	3 1 11% 37% 42% 6%	522
	21st to end	Night	5% 1 6% 41% 39% 7%	591
August	1st to 10th	Night	3 6% 45% 39% 6%	537
	11th to 20th	Night	5% 1 8% 41% 38% 7%	534
	21st to end	Night	9% 2 7% 31% 43% 8%	594
September	1st to 10th	Night	9% 1 6% 34% 44% 7%	540
	11th to 20th	Night	13% 2 10% 26% 43% 6%	540
	21st to end	Night	7% 2 11% 33% 39% 7%	540
October	1st to 10th	Night	7% 2 15% 39% 32% 5%	691
	11th to 20th	Night	14% 5% 22% 37% 19% 3	720
	21st to end	Night	17% 6% 27% 30% 18% 3	792
November	1st to 10th	Night	13% 7% 24% 36% 19% 1	740
	11th to 20th	Night	15% 10% 26% 38% 11%	760
	21st to end	Night	20% 11% 28% 28% 13% 1	818
December	1st to 10th	Night	23% 12% 27% 28% 9%	950
	11th to 20th	Night	26% 10% 31% 27% 6%	950
	21st to end	Night	24% 12% 30% 27% 7%	1045

Page generated at 2024-06-29 06:12:35. Version ac07

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