Lake Sylvia Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Sylvia Recreation Area clear sky chart from 2005-11-06 to 2024-01-22.

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% 6% 2 5% 5% 3 5% 5% 5% 7% 44%	74462
	Night	12% 5% 2 4 4 2 4 4 5% 7% 51%	75475
Transparency	Day	38% 6% 11% 22% 19% 5%	74185
	Night	33% 5% 10% 23% 22% 6%	75272
Seeing	Day	16% 10% 24% 26% 19% 5%	14227
	Night	15% 10% 25% 30% 18% 2	24174

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	17% 7% 3 4 4 2 3 3 3 6% 47%	1707
	11th to 20th	Day	15% 6% 3 6% 4 3 4 4 4 4 45%	1710
	21st to end	Day	15% 7% 3 5% 4 2 3 3 3 6% 51%	1791
February	1st to 10th	Day	21% 7% 2 5% 5% 3 4 3 4 3 44%	1620
	11th to 20th	Day	17% 7% 4 6% 6% 2 4 4 4 4 41%	1670
	21st to end	Day	22% 8% 3 6% 5% 3 4 3 4 5% 37%	1555
March	1st to 10th	Day	18% 7% 2 4 4 3 4 3 3 6% 45%	1980
	11th to 20th	Day	19% 7% 3 6% 4 3 3 4 3 4 42%	1980
	21st to end	Day	18% 7% 3 6% 6% 3 4 4 5% 7% 39%	2178
April	1st to 10th	Day	13% 7% 3 5% 5% 3 4 5% 5% 6% 45%	2138
	11th to 20th	Day	16% 5% 2 5% 5% 2 4 3 5% 6% 46%	2134
	21st to end	Day	16% 6% 3 6% 5% 2 6% 5% 5% 5% 42%	2160
May	1st to 10th	Day	17% 6% 3 5% 5% 3 5% 4 5% 7% 40%	2164
	11th to 20th	Day	13% 5% 2 6% 6% 3 5% 5% 6% 8% 41%	2302
	21st to end	Day	10% 5% 3 6% 7% 4 7% 6% 7% 8% 37%	2531
June	1st to 10th	Day	8% 6% 3 5% 5% 4 6% 6% 6% 9% 41%	2340
	11th to 20th	Day	4 4 2 4 6% 4 6% 7% 7% 11% 43%	2340
	21st to end	Day	5% 3 2 5% 6% 4 6% 5% 7% 9% 48%	2340
July	1st to 10th	Day	6% 5% 3 7% 8% 4 7% 8% 8% 11% 34%	2340
	11th to 20th	Day	6% 4 2 5% 6% 4 7% 7% 6% 10% 44%	2340
	21st to end	Day	8% 4 2 5% 6% 3 7% 6% 9% 11% 40%	2546
August	1st to 10th	Day	7% 5% 2 5% 7% 5% 7% 7% 8% 10% 38%	2328
	11th to 20th	Day	11% 5% 2 6% 5% 3 6% 5% 7% 8% 41%	2161
	21st to end	Day	9% 4 2 5% 6% 4 7% 6% 6% 8% 43%	2376
September	1st to 10th	Day	12% 5% 3 5% 5% 3 5% 5% 5% 7% 46%	2160
	11th to 20th	Day	15% 4 1 5% 5% 3 5% 5% 5% 6% 45%	2134
	21st to end	Day	11% 4 2 4 4 3 4 4 4 5% 55%	1890
October	1st to 10th	Day	8% 5% 2 5% 4 3 3 4 4 5% 57%	1800
	11th to 20th	Day	15% 5% 1 3 4 2 2 3 4 5% 55%	1800
	21st to end	Day	17% 5% 2 3 5% 2 3 3 3 6% 51%	1980
November	1st to 10th	Day	11% 5% 2 3 3 2 4 4 3 6% 58%	1858
	11th to 20th	Day	10% 4 3 5% 4 2 3 3 5% 7% 55%	1888
	21st to end	Day	17% 8% 3 5% 3 3 3 2 3 4 48%	1639
December	1st to 10th	Day	17% 7% 3 4 4 3 3 3 4 6% 47%	1520
	11th to 20th	Day	12% 8% 4 7% 5% 4 4 4 4 4 44%	1927
	21st to end	Day	13% 8% 3 6% 6% 4 5% 5% 5% 6% 39%	3135
January	1st to 10th	Night	16% 6% 2 4 5% 2 3 3 4 5% 50%	2458
	11th to 20th	Night	17% 6% 3 4 3 2 3 3 4 5% 49%	2470
	21st to end	Night	16% 5% 2 4 3 2 3 3 3 5% 53%	2600
February	1st to 10th	Night	19% 7% 3 6% 4 2 3 3 4 5% 42%	2340
	11th to 20th	Night	16% 7% 3 6% 5% 2 3 3 4 5% 45%	2176
	21st to end	Night	20% 7% 2 4 3 3 3 3 4 5% 45%	1717
March	1st to 10th	Night	17% 5% 3 5% 5% 2 3 4 4 5% 46%	1980
	11th to 20th	Night	20% 7% 3 5% 5% 2 3 3 4 5% 45%	1980
	21st to end	Night	14% 7% 3 5% 5% 3 4 4 5% 6% 43%	2178
April	1st to 10th	Night	12% 4 2 5% 5% 3 3 3 5% 6% 52%	1820
	11th to 20th	Night	12% 4 2 5% 4 2 4 4 6% 6% 51%	1775
	21st to end	Night	13% 5% 2 5% 4 3 4 4 5% 7% 49%	1800
May	1st to 10th	Night	12% 4 2 4 5% 2 5% 5% 5% 8% 49%	1792
	11th to 20th	Night	11% 7% 2 4 5% 3 5% 4 6% 8% 46%	1593
	21st to end	Night	9% 6% 3 5% 5% 3 4 4 6% 9% 46%	1745
June	1st to 10th	Night	5% 4 2 2 3 3 4 5% 8% 10% 55%	1620
	11th to 20th	Night	4 3 2 3 3 2 4 4 6% 10% 59%	1620
	21st to end	Night	4 2 2 3 3 2 3 5% 5% 9% 61%	1620
July	1st to 10th	Night	4 4 2 5% 4 4 6% 5% 7% 12% 47%	1620
	11th to 20th	Night	3 2 1 4 4 2 4 6% 7% 11% 55%	1620
	21st to end	Night	4 2 1 4 4 3 5% 6% 8% 11% 53%	1772
August	1st to 10th	Night	5% 3 2 4 5% 3 4 5% 7% 11% 50%	1611
	11th to 20th	Night	7% 4 2 4 4 2 4 5% 6% 11% 52%	1737
	21st to end	Night	6% 4 2 4 4 3 4 5% 7% 9% 52%	1980
September	1st to 10th	Night	7% 4 2 4 3 2 4 4 4 7% 58%	1800
	11th to 20th	Night	10% 5% 2 4 4 2 4 4 5% 7% 53%	1822
	21st to end	Night	10% 3 1 3 3 2 3 3 5% 7% 60%	2052
October	1st to 10th	Night	7% 4 1 3 4 2 3 3 5% 7% 60%	2160
	11th to 20th	Night	11% 3 2 4 3 2 3 3 4 5% 60%	2160
	21st to end	Night	18% 5% 2 3 3 2 3 2 2 3 56%	2376
November	1st to 10th	Night	11% 4 2 3 3 2 3 3 4 6% 59%	2220
	11th to 20th	Night	10% 4 2 3 5% 2 3 4 5% 6% 56%	2286
	21st to end	Night	14% 5% 2 4 5% 2 4 3 4 6% 51%	2536
December	1st to 10th	Night	17% 6% 2 5% 4 3 3 4 4 5% 47%	2660
	11th to 20th	Night	15% 5% 3 6% 5% 3 3 3 4 4 49%	3247
	21st to end	Night	14% 7% 3 5% 5% 3 4 4 4 6% 45%	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	42% 4 7% 23% 19% 6%	1708
	11th to 20th	Day	43% 4 8% 22% 20% 3	1710
	21st to end	Day	38% 3 6% 25% 22% 6%	1791
February	1st to 10th	Day	46% 4 9% 21% 16% 4	1620
	11th to 20th	Day	46% 4 7% 20% 18% 5%	1679
	21st to end	Day	51% 4 6% 14% 16% 9%	1555
March	1st to 10th	Day	43% 4 7% 17% 19% 10%	1980
	11th to 20th	Day	47% 5% 8% 19% 17% 4	1980
	21st to end	Day	46% 5% 10% 23% 14% 2	2178
April	1st to 10th	Day	39% 6% 10% 21% 20% 4	2138
	11th to 20th	Day	40% 5% 9% 21% 18% 7%	2134
	21st to end	Day	43% 6% 9% 19% 20% 3	2160
May	1st to 10th	Day	44% 6% 10% 18% 19% 3	2164
	11th to 20th	Day	40% 6% 13% 23% 15% 1	2306
	21st to end	Day	42% 8% 13% 23% 13% 1	2531
June	1st to 10th	Day	36% 9% 13% 24% 15% 2	2340
	11th to 20th	Day	31% 9% 15% 26% 18% 2	2340
	21st to end	Day	30% 7% 13% 26% 20% 4	2340
July	1st to 10th	Day	37% 10% 17% 22% 12% 1	2276
	11th to 20th	Day	32% 9% 14% 26% 15% 3	2271
	21st to end	Day	33% 9% 19% 26% 12% 1	2405
August	1st to 10th	Day	36% 9% 18% 27% 10% 1	2314
	11th to 20th	Day	37% 9% 12% 23% 17% 2	2161
	21st to end	Day	35% 7% 14% 25% 14% 5%	2376
September	1st to 10th	Day	36% 7% 11% 20% 19% 6%	2160
	11th to 20th	Day	36% 7% 11% 18% 22% 5%	2134
	21st to end	Day	31% 5% 8% 21% 27% 8%	1890
October	1st to 10th	Day	29% 5% 9% 23% 27% 7%	1800
	11th to 20th	Day	32% 4 5% 20% 29% 11%	1800
	21st to end	Day	36% 3 7% 22% 22% 9%	1980
November	1st to 10th	Day	29% 4 8% 27% 23% 8%	1858
	11th to 20th	Day	29% 4 8% 23% 28% 9%	1888
	21st to end	Day	43% 2 6% 18% 25% 6%	1639
December	1st to 10th	Day	40% 4 9% 24% 17% 6%	1520
	11th to 20th	Day	43% 4 6% 19% 22% 5%	1924
	21st to end	Day	44% 5% 10% 18% 17% 6%	3135
January	1st to 10th	Night	37% 3 8% 20% 27% 5%	2458
	11th to 20th	Night	39% 4 9% 21% 21% 5%	2470
	21st to end	Night	35% 3 7% 24% 26% 6%	2600
February	1st to 10th	Night	45% 4 8% 20% 18% 6%	2340
	11th to 20th	Night	42% 3 7% 21% 20% 6%	2177
	21st to end	Night	42% 3 7% 17% 21% 9%	1717
March	1st to 10th	Night	40% 3 10% 15% 21% 12%	1980
	11th to 20th	Night	45% 4 7% 21% 17% 7%	1980
	21st to end	Night	43% 4 9% 21% 20% 4	2178
April	1st to 10th	Night	33% 5% 11% 24% 20% 8%	1820
	11th to 20th	Night	32% 5% 9% 24% 21% 9%	1775
	21st to end	Night	35% 4 11% 25% 21% 3	1800
May	1st to 10th	Night	34% 7% 13% 23% 19% 6%	1792
	11th to 20th	Night	36% 6% 14% 25% 17% 2	1594
	21st to end	Night	34% 7% 16% 26% 16% 1	1746
June	1st to 10th	Night	23% 8% 16% 31% 20% 2	1620
	11th to 20th	Night	21% 6% 13% 33% 24% 2	1620
	21st to end	Night	20% 7% 13% 29% 24% 7%	1620
July	1st to 10th	Night	27% 8% 22% 25% 17% 1	1575
	11th to 20th	Night	20% 9% 19% 28% 19% 5%	1566
	21st to end	Night	22% 10% 17% 33% 18% 1	1673
August	1st to 10th	Night	25% 9% 19% 32% 14% 1	1601
	11th to 20th	Night	26% 8% 15% 29% 20% 2	1737
	21st to end	Night	26% 8% 19% 25% 19% 3	1980
September	1st to 10th	Night	27% 7% 11% 26% 23% 8%	1800
	11th to 20th	Night	31% 6% 11% 20% 26% 7%	1822
	21st to end	Night	24% 4 9% 23% 30% 9%	2052
October	1st to 10th	Night	25% 4 12% 23% 25% 11%	2160
	11th to 20th	Night	28% 4 7% 18% 32% 12%	2160
	21st to end	Night	36% 3 5% 21% 25% 10%	2376
November	1st to 10th	Night	28% 4 7% 24% 26% 11%	2220
	11th to 20th	Night	30% 3 7% 23% 27% 10%	2286
	21st to end	Night	36% 4 7% 19% 28% 6%	2536
December	1st to 10th	Night	40% 4 9% 19% 21% 7%	2660
	11th to 20th	Night	40% 3 6% 20% 25% 7%	3249
	21st to end	Night	40% 5% 9% 23% 20% 4	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% 32% 17% 4 1	270
	11th to 20th	Day	26% 24% 33% 14% 2	270
	21st to end	Day	23% 25% 34% 12% 6%	267
February	1st to 10th	Day	29% 18% 36% 12% 5%	240
	11th to 20th	Day	30% 29% 28% 11% 1	240
	21st to end	Day	39% 23% 29% 8% 2 1	198
March	1st to 10th	Day	26% 20% 36% 13% 5%	240
	11th to 20th	Day	35% 17% 34% 13% 1	240
	21st to end	Day	28% 25% 33% 10% 3	264
April	1st to 10th	Day	20% 19% 37% 16% 7% 1	398
	11th to 20th	Day	26% 14% 34% 19% 6% 1	412
	21st to end	Day	20% 16% 37% 18% 8% 1	420
May	1st to 10th	Day	19% 16% 32% 24% 9% 1	427
	11th to 20th	Day	15% 10% 30% 27% 16% 2	625
	21st to end	Day	11% 8% 27% 33% 16% 5%	679
June	1st to 10th	Day	10% 5% 21% 31% 27% 7%	630
	11th to 20th	Day	6% 3 20% 39% 27% 5%	630
	21st to end	Day	5% 4 23% 35% 25% 7%	630
July	1st to 10th	Day	5% 2 15% 33% 34% 10%	621
	11th to 20th	Day	5% 2 15% 34% 33% 11%	618
	21st to end	Day	7% 1 11% 35% 32% 13%	684
August	1st to 10th	Day	7% 2 14% 36% 33% 7%	626
	11th to 20th	Day	15% 1 9% 34% 33% 9%	475
	21st to end	Day	10% 2 6% 31% 36% 15%	495
September	1st to 10th	Day	12% 2 12% 27% 37% 10%	450
	11th to 20th	Day	11% 2 13% 28% 35% 11%	424
	21st to end	Day	13% 5% 18% 37% 21% 6%	270
October	1st to 10th	Day	6% 5% 29% 38% 19% 4	270
	11th to 20th	Day	17% 13% 34% 23% 11% 2	270
	21st to end	Day	28% 15% 30% 19% 7% 1	297
November	1st to 10th	Day	16% 13% 37% 18% 14% 2	270
	11th to 20th	Day	14% 18% 38% 23% 5% 1	270
	21st to end	Day	28% 16% 25% 21% 10%	270
December	1st to 10th	Day	22% 26% 26% 18% 7% 1	270
	11th to 20th	Day	24% 21% 30% 18% 6%	270
	21st to end	Day	24% 16% 43% 14% 2	297
January	1st to 10th	Night	21% 17% 30% 27% 4	950
	11th to 20th	Night	23% 17% 33% 23% 4	950
	21st to end	Night	20% 16% 36% 25% 3	1000
February	1st to 10th	Night	25% 16% 33% 22% 4	900
	11th to 20th	Night	22% 19% 38% 20% 1	781
	21st to end	Night	28% 17% 32% 20% 3	533
March	1st to 10th	Night	21% 14% 31% 29% 5%	540
	11th to 20th	Night	23% 12% 33% 28% 4 1	540
	21st to end	Night	18% 13% 35% 27% 6%	594
April	1st to 10th	Night	15% 15% 35% 27% 7%	540
	11th to 20th	Night	15% 14% 33% 26% 11%	533
	21st to end	Night	14% 11% 38% 26% 9%	540
May	1st to 10th	Night	14% 7% 28% 40% 10% 1	540
	11th to 20th	Night	12% 9% 28% 29% 21% 1	531
	21st to end	Night	10% 4 24% 33% 23% 5%	584
June	1st to 10th	Night	7% 2 13% 38% 35% 5%	540
	11th to 20th	Night	5% 1 13% 44% 34% 3	540
	21st to end	Night	4 1 14% 39% 37% 5%	540
July	1st to 10th	Night	3 1 11% 35% 42% 8%	525
	11th to 20th	Night	4 1 11% 33% 43% 8%	522
	21st to end	Night	3 1 9% 36% 41% 10%	591
August	1st to 10th	Night	6% 1 7% 39% 42% 5%	537
	11th to 20th	Night	9% 1 10% 35% 39% 6%	534
	21st to end	Night	7% 1 8% 33% 44% 7%	594
September	1st to 10th	Night	10% 1 10% 31% 45% 4	540
	11th to 20th	Night	12% 1 11% 33% 39% 4	540
	21st to end	Night	11% 2 16% 31% 36% 5%	612
October	1st to 10th	Night	9% 3 18% 36% 31% 3	720
	11th to 20th	Night	12% 8% 27% 37% 16% 1	720
	21st to end	Night	21% 9% 25% 28% 14% 2	792
November	1st to 10th	Night	11% 9% 26% 38% 14% 1	740
	11th to 20th	Night	13% 11% 32% 33% 11%	760
	21st to end	Night	16% 16% 28% 27% 11%	826
December	1st to 10th	Night	22% 12% 32% 27% 7%	950
	11th to 20th	Night	20% 14% 29% 30% 6%	950
	21st to end	Night	21% 17% 30% 27% 5%	1045

Page generated at 2024-01-19 08:28:34. Version ac07

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