San Marcos Baptist Academy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the San Marcos Baptist Academy clear sky chart from 2005-11-06 to 2024-02-15.

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 4 4 5% 7% 45%	78810
	Night	15% 5% 2 4 4 2 3 3 4 7% 51%	80325
Transparency	Day	37% 7% 10% 19% 19% 9%	78535
	Night	34% 6% 11% 19% 19% 11%	80120
Seeing	Day	14% 7% 20% 29% 24% 7%	13782
	Night	16% 6% 24% 35% 17% 1	23878

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% 8% 2 4 3 2 3 3 4 6% 50%	2847
	11th to 20th	Day	19% 4 2 3 3 1 2 2 4 5% 55%	2850
	21st to end	Day	20% 7% 2 4 4 2 3 4 4 8% 42%	3341
February	1st to 10th	Day	22% 6% 2 5% 4 2 4 3 5% 4 44%	1900
	11th to 20th	Day	21% 7% 2 4 3 2 3 4 4 6% 44%	1789
	21st to end	Day	20% 6% 3 4 3 2 3 3 3 6% 47%	1480
March	1st to 10th	Day	21% 7% 3 5% 4 3 4 3 5% 6% 40%	1964
	11th to 20th	Day	18% 6% 2 4 5% 3 4 4 4 5% 45%	1980
	21st to end	Day	17% 6% 3 4 4 2 3 4 4 5% 47%	2178
April	1st to 10th	Day	16% 8% 3 5% 5% 3 4 4 4 6% 42%	1980
	11th to 20th	Day	21% 5% 3 6% 4 3 4 4 3 6% 42%	1956
	21st to end	Day	16% 7% 2 5% 5% 3 4 4 4 7% 45%	2277
May	1st to 10th	Day	17% 5% 3 6% 6% 2 4 5% 6% 6% 39%	2340
	11th to 20th	Day	15% 7% 3 7% 6% 3 6% 5% 5% 7% 38%	2302
	21st to end	Day	16% 6% 3 6% 6% 3 7% 5% 7% 8% 33%	2531
June	1st to 10th	Day	7% 4 1 5% 4 3 6% 6% 7% 9% 47%	2340
	11th to 20th	Day	8% 5% 3 5% 6% 3 6% 6% 6% 9% 45%	2340
	21st to end	Day	8% 5% 3 7% 7% 5% 6% 7% 7% 10% 34%	2340
July	1st to 10th	Day	11% 6% 3 6% 7% 5% 7% 6% 5% 9% 37%	2340
	11th to 20th	Day	4 3 2 4 5% 4 6% 7% 7% 11% 47%	2340
	21st to end	Day	5% 3 2 3 5% 4 5% 6% 7% 11% 47%	2546
August	1st to 10th	Day	2 2 1 3 4 2 4 4 5% 11% 60%	2328
	11th to 20th	Day	5% 4 1 4 4 4 6% 6% 6% 9% 51%	2129
	21st to end	Day	6% 3 2 4 6% 4 6% 7% 8% 12% 41%	2268
September	1st to 10th	Day	9% 6% 3 7% 6% 4 5% 5% 5% 7% 43%	1980
	11th to 20th	Day	12% 6% 3 6% 6% 4 5% 5% 6% 8% 39%	1980
	21st to end	Day	9% 4 2 4 5% 3 6% 6% 6% 8% 48%	1980
October	1st to 10th	Day	7% 4 2 5% 5% 3 5% 5% 6% 7% 52%	1980
	11th to 20th	Day	13% 5% 2 4 4 4 4 4 4 7% 49%	1854
	21st to end	Day	12% 4 2 4 3 2 3 4 4 5% 57%	1980
November	1st to 10th	Day	15% 7% 3 5% 4 2 3 5% 5% 6% 45%	1858
	11th to 20th	Day	14% 5% 2 5% 4 3 4 4 4 5% 50%	1796
	21st to end	Day	19% 7% 3 5% 5% 3 3 3 4 4 44%	1710
December	1st to 10th	Day	16% 7% 3 4 4 2 3 4 5% 6% 46%	1710
	11th to 20th	Day	17% 7% 3 5% 5% 3 4 4 4 4 43%	2161
	21st to end	Day	18% 6% 2 3 3 2 2 3 3 5% 53%	3135
January	1st to 10th	Night	21% 6% 1 2 2 1 2 2 3 6% 52%	4108
	11th to 20th	Night	15% 3 1 3 2 1 2 2 3 3 65%	4120
	21st to end	Night	23% 6% 3 5% 4 2 2 3 3 7% 42%	4340
February	1st to 10th	Night	20% 7% 3 4 4 2 3 3 4 6% 45%	2280
	11th to 20th	Night	22% 6% 2 3 3 2 3 3 2 6% 48%	2152
	21st to end	Night	24% 6% 2 3 3 2 3 3 4 6% 44%	1776
March	1st to 10th	Night	20% 5% 2 4 4 2 4 3 4 7% 43%	1994
	11th to 20th	Night	18% 8% 3 5% 4 2 3 4 4 5% 43%	1980
	21st to end	Night	17% 6% 2 4 2 2 4 3 4 7% 49%	2178
April	1st to 10th	Night	15% 6% 2 4 5% 2 3 4 5% 7% 46%	1980
	11th to 20th	Night	20% 6% 2 4 4 3 4 3 4 6% 44%	1953
	21st to end	Night	18% 6% 3 4 4 2 3 3 4 5% 48%	1677
May	1st to 10th	Night	15% 7% 3 4 4 3 4 5% 5% 6% 44%	1620
	11th to 20th	Night	14% 7% 2 5% 4 3 4 4 5% 8% 45%	1593
	21st to end	Night	14% 5% 3 4 4 3 4 4 7% 10% 43%	1745
June	1st to 10th	Night	6% 4 1 3 3 2 4 4 5% 8% 60%	1620
	11th to 20th	Night	5% 3 2 3 4 2 3 4 5% 10% 57%	1620
	21st to end	Night	8% 4 2 4 4 3 4 5% 7% 9% 49%	1620
July	1st to 10th	Night	9% 4 2 4 3 3 4 5% 7% 11% 46%	1620
	11th to 20th	Night	3 2 1 3 3 2 4 5% 6% 11% 60%	1620
	21st to end	Night	5% 2 1 2 4 2 4 5% 6% 11% 57%	1772
August	1st to 10th	Night	2 1 1 2 2 2 2 4 5% 9% 70%	1611
	11th to 20th	Night	5% 4 2 4 4 3 5% 5% 7% 10% 52%	1767
	21st to end	Night	7% 3 1 4 5% 4 5% 5% 7% 11% 49%	2088
September	1st to 10th	Night	8% 5% 2 5% 5% 3 4 4 5% 9% 49%	1980
	11th to 20th	Night	10% 5% 3 5% 5% 3 4 5% 6% 8% 45%	1980
	21st to end	Night	9% 5% 2 4 4 3 4 4 6% 8% 52%	1980
October	1st to 10th	Night	7% 3 2 3 4 2 4 3 4 8% 60%	1980
	11th to 20th	Night	14% 6% 2 4 4 2 3 3 5% 5% 52%	2088
	21st to end	Night	16% 4 1 3 3 2 2 2 3 4 59%	2376
November	1st to 10th	Night	14% 6% 2 5% 3 1 3 3 3 6% 53%	2220
	11th to 20th	Night	12% 5% 2 4 4 2 4 4 4 6% 53%	2379
	21st to end	Night	20% 6% 2 4 3 2 4 3 4 6% 46%	2470
December	1st to 10th	Night	17% 6% 2 4 3 2 3 4 5% 5% 50%	2470
	11th to 20th	Night	19% 8% 3 4 4 2 3 3 3 5% 46%	3036
	21st to end	Night	21% 5% 2 3 2 2 2 2 3 5% 53%	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	36% 4 6% 14% 25% 14%	2848
	11th to 20th	Day	33% 3 7% 15% 26% 17%	2850
	21st to end	Day	41% 4 6% 11% 28% 10%	3341
February	1st to 10th	Day	44% 4 6% 12% 20% 15%	1900
	11th to 20th	Day	42% 4 8% 16% 17% 12%	1799
	21st to end	Day	41% 4 8% 15% 17% 15%	1480
March	1st to 10th	Day	46% 5% 10% 12% 18% 10%	1964
	11th to 20th	Day	41% 5% 7% 12% 19% 14%	1980
	21st to end	Day	39% 5% 8% 17% 19% 12%	2178
April	1st to 10th	Day	44% 5% 8% 17% 16% 11%	1980
	11th to 20th	Day	43% 5% 8% 15% 18% 11%	1956
	21st to end	Day	41% 5% 6% 19% 19% 10%	2277
May	1st to 10th	Day	45% 7% 8% 15% 18% 7%	2340
	11th to 20th	Day	44% 9% 9% 18% 17% 4	2306
	21st to end	Day	46% 8% 13% 17% 15% 1	2531
June	1st to 10th	Day	29% 9% 14% 26% 19% 3	2340
	11th to 20th	Day	35% 7% 12% 25% 17% 4	2340
	21st to end	Day	41% 10% 11% 22% 12% 3	2340
July	1st to 10th	Day	42% 11% 12% 24% 10% 2	2276
	11th to 20th	Day	26% 10% 19% 25% 17% 2	2271
	21st to end	Day	26% 9% 20% 32% 13% 1	2405
August	1st to 10th	Day	20% 7% 17% 35% 19% 1	2314
	11th to 20th	Day	28% 10% 17% 29% 13% 4	2129
	21st to end	Day	32% 11% 17% 24% 12% 3	2268
September	1st to 10th	Day	39% 8% 9% 20% 15% 8%	1980
	11th to 20th	Day	41% 8% 13% 17% 16% 5%	1980
	21st to end	Day	32% 9% 11% 20% 17% 11%	1980
October	1st to 10th	Day	29% 7% 12% 20% 22% 10%	1980
	11th to 20th	Day	34% 5% 11% 14% 19% 16%	1854
	21st to end	Day	29% 5% 7% 15% 24% 20%	1980
November	1st to 10th	Day	38% 7% 9% 17% 18% 10%	1858
	11th to 20th	Day	36% 5% 9% 17% 20% 13%	1796
	21st to end	Day	44% 4 6% 14% 18% 13%	1710
December	1st to 10th	Day	39% 5% 10% 17% 20% 8%	1710
	11th to 20th	Day	42% 7% 6% 10% 21% 14%	2159
	21st to end	Day	36% 3 6% 15% 26% 14%	3135
January	1st to 10th	Night	35% 4 6% 14% 21% 19%	4108
	11th to 20th	Night	27% 3 5% 16% 30% 19%	4120
	21st to end	Night	44% 5% 5% 11% 24% 11%	4340
February	1st to 10th	Night	41% 4 8% 12% 19% 17%	2280
	11th to 20th	Night	40% 4 7% 15% 19% 15%	2152
	21st to end	Night	43% 4 6% 15% 17% 16%	1776
March	1st to 10th	Night	42% 6% 9% 15% 18% 11%	1994
	11th to 20th	Night	44% 5% 9% 11% 18% 15%	1980
	21st to end	Night	38% 6% 10% 15% 18% 13%	2178
April	1st to 10th	Night	38% 6% 9% 18% 16% 13%	1980
	11th to 20th	Night	42% 5% 8% 14% 16% 15%	1953
	21st to end	Night	40% 5% 9% 20% 17% 10%	1677
May	1st to 10th	Night	40% 7% 9% 17% 17% 9%	1620
	11th to 20th	Night	37% 8% 11% 24% 16% 4	1594
	21st to end	Night	36% 8% 16% 26% 14% 1	1746
June	1st to 10th	Night	23% 6% 17% 28% 24% 3	1620
	11th to 20th	Night	22% 6% 17% 32% 18% 4	1620
	21st to end	Night	29% 10% 18% 26% 14% 3	1620
July	1st to 10th	Night	31% 11% 19% 28% 9% 1	1575
	11th to 20th	Night	17% 11% 24% 31% 17% 1	1566
	21st to end	Night	19% 9% 27% 35% 9% 1	1673
August	1st to 10th	Night	12% 7% 26% 37% 17% 1	1601
	11th to 20th	Night	24% 13% 21% 29% 11% 2	1767
	21st to end	Night	27% 12% 21% 27% 11% 3	2088
September	1st to 10th	Night	32% 8% 17% 22% 15% 6%	1980
	11th to 20th	Night	36% 8% 15% 22% 13% 5%	1980
	21st to end	Night	29% 8% 15% 20% 17% 11%	1980
October	1st to 10th	Night	24% 5% 13% 24% 21% 12%	1980
	11th to 20th	Night	34% 4 10% 16% 19% 18%	2088
	21st to end	Night	30% 4 7% 16% 22% 22%	2376
November	1st to 10th	Night	34% 6% 9% 18% 20% 13%	2220
	11th to 20th	Night	33% 6% 9% 17% 20% 15%	2379
	21st to end	Night	41% 4 8% 15% 18% 14%	2470
December	1st to 10th	Night	37% 5% 8% 19% 19% 11%	2470
	11th to 20th	Night	42% 5% 6% 10% 19% 19%	3037
	21st to end	Night	36% 4 4 14% 29% 13%	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	22% 14% 34% 25% 4 1	270
	11th to 20th	Day	27% 14% 25% 25% 8% 2	270
	21st to end	Day	19% 13% 36% 25% 6%	297
February	1st to 10th	Day	34% 11% 28% 20% 8%	270
	11th to 20th	Day	25% 17% 33% 20% 5%	252
	21st to end	Day	25% 20% 37% 17% 1	198
March	1st to 10th	Day	25% 15% 37% 18% 5%	240
	11th to 20th	Day	19% 17% 41% 18% 5% 1	240
	21st to end	Day	22% 13% 34% 25% 6%	264
April	1st to 10th	Day	22% 12% 40% 22% 5%	240
	11th to 20th	Day	21% 18% 31% 20% 11%	234
	21st to end	Day	19% 13% 35% 25% 7%	537
May	1st to 10th	Day	16% 12% 34% 28% 10%	603
	11th to 20th	Day	18% 7% 27% 33% 14% 2	625
	21st to end	Day	17% 4 23% 36% 18% 2	679
June	1st to 10th	Day	8% 1 12% 40% 31% 7%	630
	11th to 20th	Day	8% 1 13% 45% 30% 4	630
	21st to end	Day	10% 2 12% 36% 29% 11%	630
July	1st to 10th	Day	9% 2 9% 33% 36% 12%	621
	11th to 20th	Day	3 5% 30% 50% 11%	618
	21st to end	Day	4 1 3 34% 45% 13%	684
August	1st to 10th	Day	3 5% 27% 50% 14%	626
	11th to 20th	Day	5% 1 4 31% 44% 14%	443
	21st to end	Day	5% 1 4 24% 39% 27%	387
September	1st to 10th	Day	9% 3 28% 41% 19%	270
	11th to 20th	Day	8% 1 3 24% 47% 17%	270
	21st to end	Day	9% 1 8% 26% 39% 17%	270
October	1st to 10th	Day	5% 2 16% 31% 35% 11%	270
	11th to 20th	Day	12% 4 19% 36% 23% 7%	270
	21st to end	Day	21% 10% 25% 23% 15% 6%	297
November	1st to 10th	Day	19% 7% 27% 28% 16% 4	270
	11th to 20th	Day	20% 9% 26% 29% 15% 2	270
	21st to end	Day	22% 14% 35% 17% 11% 1	270
December	1st to 10th	Day	19% 7% 33% 29% 7% 6%	270
	11th to 20th	Day	23% 17% 26% 27% 8%	270
	21st to end	Day	22% 9% 36% 24% 8%	297
January	1st to 10th	Night	21% 9% 28% 32% 9% 1	950
	11th to 20th	Night	21% 9% 30% 31% 8%	950
	21st to end	Night	23% 9% 28% 32% 8%	931
February	1st to 10th	Night	26% 11% 30% 26% 6%	760
	11th to 20th	Night	26% 11% 33% 26% 4	722
	21st to end	Night	26% 13% 38% 21% 2	592
March	1st to 10th	Night	23% 10% 35% 28% 3	554
	11th to 20th	Night	24% 9% 33% 29% 6%	540
	21st to end	Night	19% 8% 40% 29% 4 1	594
April	1st to 10th	Night	17% 8% 42% 29% 4	540
	11th to 20th	Night	20% 11% 37% 26% 5%	533
	21st to end	Night	19% 9% 39% 25% 8%	540
May	1st to 10th	Night	17% 9% 39% 29% 6%	540
	11th to 20th	Night	17% 5% 30% 37% 11%	531
	21st to end	Night	16% 3 30% 38% 13%	584
June	1st to 10th	Night	7% 2 19% 48% 24% 1	540
	11th to 20th	Night	4 2 27% 51% 15% 1	540
	21st to end	Night	6% 2 17% 44% 27% 4	540
July	1st to 10th	Night	9% 1 10% 45% 32% 3	525
	11th to 20th	Night	3 11% 48% 35% 2	522
	21st to end	Night	4 1 8% 49% 35% 3	591
August	1st to 10th	Night	2 8% 48% 38% 4	537
	11th to 20th	Night	5% 1 7% 48% 36% 4	534
	21st to end	Night	6% 1 6% 37% 45% 5%	594
September	1st to 10th	Night	8% 1 8% 38% 40% 5%	540
	11th to 20th	Night	11% 1 6% 36% 42% 3	540
	21st to end	Night	10% 1 12% 34% 39% 3	540
October	1st to 10th	Night	7% 1 11% 45% 31% 5%	540
	11th to 20th	Night	14% 4 20% 36% 23% 2	648
	21st to end	Night	16% 7% 22% 32% 20% 2	792
November	1st to 10th	Night	14% 6% 20% 37% 21% 1	740
	11th to 20th	Night	14% 6% 25% 38% 15% 2	859
	21st to end	Night	22% 10% 25% 30% 12% 1	950
December	1st to 10th	Night	20% 7% 28% 32% 11% 1	950
	11th to 20th	Night	24% 10% 26% 32% 8%	950
	21st to end	Night	23% 7% 28% 33% 8%	1045

Page generated at 2024-02-12 05:35:33. Version ac07

Copyright 2024 Attilla Danko