Escondido Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Escondido Ranch clear sky chart from 2005-11-06 to 2024-03-18.

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	10% 5% 2 5% 5% 3 4 5% 5% 7% 49%	79207
	Night	10% 4 2 4 4 2 4 4 5% 8% 54%	80647
Transparency	Day	33% 7% 11% 20% 19% 9%	78933
	Night	29% 7% 13% 22% 18% 12%	80442
Seeing	Day	10% 5% 21% 34% 24% 6%	13637
	Night	12% 5% 30% 40% 12% 1	23796

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% 5% 2 4 4 2 3 3 3 4 55%	2847
	11th to 20th	Day	14% 4 2 3 3 2 2 2 4 6% 58%	2954
	21st to end	Day	18% 7% 3 6% 5% 3 4 5% 5% 7% 38%	3487
February	1st to 10th	Day	16% 7% 3 6% 5% 3 3 4 4 5% 45%	1900
	11th to 20th	Day	15% 6% 3 4 4 2 3 3 4 6% 50%	1849
	21st to end	Day	14% 6% 2 3 4 2 3 4 4 6% 52%	1570
March	1st to 10th	Day	15% 6% 3 5% 5% 2 4 4 6% 7% 43%	2041
	11th to 20th	Day	13% 5% 3 6% 5% 3 5% 4 5% 7% 45%	2057
	21st to end	Day	9% 4 2 5% 4 3 4 4 5% 8% 53%	2178
April	1st to 10th	Day	10% 5% 3 5% 4 2 4 5% 5% 8% 49%	1980
	11th to 20th	Day	13% 6% 2 6% 5% 3 4 4 5% 6% 46%	1960
	21st to end	Day	10% 5% 2 5% 5% 3 4 5% 4 6% 51%	2200
May	1st to 10th	Day	9% 5% 3 6% 5% 3 5% 5% 6% 8% 46%	2340
	11th to 20th	Day	9% 5% 2 5% 6% 4 5% 5% 6% 7% 45%	2302
	21st to end	Day	6% 5% 2 6% 6% 5% 6% 6% 8% 9% 42%	2531
June	1st to 10th	Day	4 2 1 3 5% 3 5% 6% 6% 10% 56%	2340
	11th to 20th	Day	3 3 1 3 5% 4 4 5% 6% 9% 55%	2340
	21st to end	Day	7% 4 2 5% 7% 4 6% 6% 6% 11% 43%	2340
July	1st to 10th	Day	8% 5% 3 6% 7% 4 6% 6% 7% 8% 39%	2340
	11th to 20th	Day	4 4 2 4 5% 4 5% 5% 6% 8% 55%	2340
	21st to end	Day	3 2 1 3 5% 3 5% 5% 6% 10% 56%	2544
August	1st to 10th	Day	1 2 1 3 4 3 4 5% 5% 9% 65%	2149
	11th to 20th	Day	3 3 2 3 5% 3 4 5% 6% 10% 56%	2123
	21st to end	Day	6% 4 2 5% 5% 4 5% 6% 7% 9% 45%	2287
September	1st to 10th	Day	10% 6% 3 6% 6% 5% 6% 6% 5% 8% 40%	1980
	11th to 20th	Day	10% 5% 2 5% 7% 4 6% 6% 8% 8% 40%	1980
	21st to end	Day	8% 5% 2 4 4 2 6% 5% 6% 9% 48%	1980
October	1st to 10th	Day	7% 3 2 4 4 2 5% 5% 6% 7% 55%	1980
	11th to 20th	Day	11% 4 2 4 3 3 4 4 5% 6% 54%	1931
	21st to end	Day	9% 3 2 4 3 2 4 4 3 5% 62%	1980
November	1st to 10th	Day	12% 6% 3 6% 4 3 3 5% 5% 6% 48%	1858
	11th to 20th	Day	13% 6% 3 5% 4 2 3 4 4 6% 50%	1803
	21st to end	Day	15% 7% 2 6% 4 3 4 4 4 5% 46%	1710
December	1st to 10th	Day	17% 6% 3 5% 3 3 3 3 4 7% 46%	1710
	11th to 20th	Day	18% 7% 3 5% 4 2 3 4 4 6% 43%	2161
	21st to end	Day	13% 5% 2 5% 4 3 4 4 3 6% 50%	3135
January	1st to 10th	Night	16% 6% 2 4 3 2 3 3 4 6% 53%	4108
	11th to 20th	Night	13% 4 2 3 2 1 2 2 3 6% 61%	4044
	21st to end	Night	21% 6% 3 6% 4 2 3 4 5% 7% 38%	4180
February	1st to 10th	Night	13% 5% 2 4 5% 2 4 4 5% 7% 48%	2280
	11th to 20th	Night	16% 6% 2 4 3 2 3 3 3 7% 51%	2218
	21st to end	Night	12% 5% 1 4 3 2 4 4 5% 6% 52%	1884
March	1st to 10th	Night	13% 5% 2 4 5% 3 4 5% 4 8% 47%	2138
	11th to 20th	Night	12% 6% 3 5% 5% 3 4 3 5% 7% 48%	2068
	21st to end	Night	9% 5% 1 4 3 2 3 4 5% 7% 57%	2178
April	1st to 10th	Night	7% 5% 2 4 4 2 5% 5% 6% 9% 51%	1980
	11th to 20th	Night	10% 5% 2 4 3 3 4 4 5% 8% 50%	1945
	21st to end	Night	8% 5% 2 4 5% 2 5% 4 4 8% 51%	1756
May	1st to 10th	Night	6% 4 1 4 4 3 3 5% 8% 11% 52%	1620
	11th to 20th	Night	8% 4 2 4 4 2 5% 4 6% 10% 50%	1593
	21st to end	Night	5% 3 1 4 5% 3 4 6% 8% 10% 52%	1745
June	1st to 10th	Night	2 2 1 3 3 2 3 4 4 9% 68%	1620
	11th to 20th	Night	2 2 1 2 2 2 3 4 5% 9% 67%	1620
	21st to end	Night	4 4 2 3 4 3 5% 4 6% 10% 55%	1620
July	1st to 10th	Night	7% 4 2 3 4 3 4 5% 6% 9% 51%	1620
	11th to 20th	Night	2 1 1 1 3 2 3 3 5% 10% 69%	1620
	21st to end	Night	3 1 2 3 1 4 4 5% 11% 66%	1772
August	1st to 10th	Night	1 1 1 1 1 2 3 5% 8% 76%	1786
	11th to 20th	Night	3 2 1 3 3 2 4 4 5% 10% 64%	1778
	21st to end	Night	3 3 1 4 4 3 4 4 5% 9% 57%	2066
September	1st to 10th	Night	7% 5% 2 5% 5% 3 4 4 6% 9% 49%	1980
	11th to 20th	Night	9% 5% 2 4 4 3 5% 5% 7% 9% 48%	1980
	21st to end	Night	7% 4 2 4 3 3 3 3 5% 8% 57%	1980
October	1st to 10th	Night	5% 3 1 3 2 2 4 3 5% 7% 65%	1980
	11th to 20th	Night	10% 4 2 3 3 2 3 3 4 7% 59%	2010
	21st to end	Night	10% 4 1 3 3 1 3 3 3 5% 65%	2376
November	1st to 10th	Night	9% 5% 2 4 4 3 3 3 4 6% 56%	2220
	11th to 20th	Night	12% 4 2 4 3 2 3 3 4 7% 55%	2374
	21st to end	Night	15% 5% 2 4 5% 2 3 4 5% 6% 50%	2470
December	1st to 10th	Night	17% 5% 2 4 3 2 3 3 4 6% 52%	2470
	11th to 20th	Night	17% 6% 3 4 3 2 3 4 4 6% 47%	3036
	21st to end	Night	12% 5% 2 5% 4 2 4 4 5% 7% 49%	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	34% 5% 5% 12% 27% 17%	2848
	11th to 20th	Day	29% 4 5% 20% 26% 17%	2954
	21st to end	Day	44% 5% 6% 15% 21% 9%	3487
February	1st to 10th	Day	42% 5% 6% 11% 19% 16%	1900
	11th to 20th	Day	36% 5% 8% 18% 19% 14%	1859
	21st to end	Day	33% 5% 9% 19% 21% 13%	1570
March	1st to 10th	Day	39% 7% 10% 19% 15% 10%	2041
	11th to 20th	Day	39% 6% 9% 14% 17% 15%	2057
	21st to end	Day	31% 6% 13% 16% 20% 14%	2178
April	1st to 10th	Day	33% 6% 12% 19% 19% 11%	1980
	11th to 20th	Day	38% 5% 9% 17% 15% 14%	1960
	21st to end	Day	33% 6% 8% 19% 19% 14%	2200
May	1st to 10th	Day	34% 8% 10% 20% 17% 10%	2340
	11th to 20th	Day	35% 9% 10% 19% 22% 5%	2306
	21st to end	Day	33% 10% 12% 23% 19% 2	2531
June	1st to 10th	Day	21% 8% 15% 29% 23% 5%	2340
	11th to 20th	Day	23% 8% 12% 28% 25% 4	2340
	21st to end	Day	33% 9% 16% 25% 14% 2	2340
July	1st to 10th	Day	38% 10% 15% 23% 12% 2	2276
	11th to 20th	Day	26% 7% 17% 27% 20% 3	2271
	21st to end	Day	21% 9% 20% 35% 14% 1	2403
August	1st to 10th	Day	18% 7% 16% 36% 21% 2	2136
	11th to 20th	Day	22% 9% 18% 33% 16% 2	2123
	21st to end	Day	32% 9% 18% 25% 13% 3	2287
September	1st to 10th	Day	42% 10% 14% 17% 13% 5%	1980
	11th to 20th	Day	39% 11% 13% 18% 16% 3	1980
	21st to end	Day	32% 8% 13% 22% 15% 10%	1980
October	1st to 10th	Day	26% 8% 11% 20% 28% 6%	1980
	11th to 20th	Day	30% 6% 10% 21% 18% 14%	1931
	21st to end	Day	26% 4 7% 15% 28% 20%	1980
November	1st to 10th	Day	35% 5% 8% 19% 22% 10%	1858
	11th to 20th	Day	36% 5% 9% 18% 19% 13%	1803
	21st to end	Day	40% 5% 7% 18% 17% 13%	1710
December	1st to 10th	Day	40% 5% 8% 20% 19% 8%	1710
	11th to 20th	Day	41% 7% 8% 11% 17% 16%	2159
	21st to end	Day	35% 6% 8% 17% 24% 10%	3135
January	1st to 10th	Night	31% 6% 7% 13% 19% 23%	4108
	11th to 20th	Night	27% 4 5% 19% 23% 23%	4044
	21st to end	Night	45% 6% 6% 12% 20% 11%	4180
February	1st to 10th	Night	35% 6% 8% 15% 16% 19%	2280
	11th to 20th	Night	34% 5% 9% 17% 18% 17%	2218
	21st to end	Night	33% 5% 10% 19% 20% 14%	1884
March	1st to 10th	Night	34% 8% 13% 18% 15% 12%	2138
	11th to 20th	Night	38% 6% 12% 14% 14% 16%	2068
	21st to end	Night	26% 7% 15% 20% 17% 14%	2178
April	1st to 10th	Night	27% 8% 14% 21% 18% 12%	1980
	11th to 20th	Night	30% 8% 14% 18% 15% 15%	1945
	21st to end	Night	32% 7% 13% 18% 19% 12%	1756
May	1st to 10th	Night	26% 8% 16% 22% 16% 12%	1620
	11th to 20th	Night	27% 9% 13% 29% 18% 5%	1594
	21st to end	Night	23% 11% 18% 31% 16% 1	1746
June	1st to 10th	Night	15% 7% 20% 33% 23% 3	1620
	11th to 20th	Night	15% 6% 14% 36% 25% 4	1620
	21st to end	Night	25% 9% 20% 28% 16% 3	1620
July	1st to 10th	Night	26% 11% 24% 29% 10% 1	1575
	11th to 20th	Night	12% 8% 26% 34% 19% 1	1566
	21st to end	Night	12% 8% 28% 40% 11% 1	1673
August	1st to 10th	Night	8% 6% 23% 47% 15% 1	1776
	11th to 20th	Night	16% 8% 25% 39% 12% 1	1778
	21st to end	Night	22% 10% 21% 33% 12% 2	2066
September	1st to 10th	Night	31% 10% 21% 18% 14% 5%	1980
	11th to 20th	Night	30% 10% 16% 25% 16% 2	1980
	21st to end	Night	25% 7% 14% 28% 18% 9%	1980
October	1st to 10th	Night	19% 6% 13% 29% 21% 11%	1980
	11th to 20th	Night	27% 5% 12% 23% 18% 15%	2010
	21st to end	Night	23% 4 8% 17% 25% 22%	2376
November	1st to 10th	Night	28% 6% 10% 21% 24% 11%	2220
	11th to 20th	Night	30% 6% 12% 18% 20% 13%	2374
	21st to end	Night	35% 5% 9% 21% 18% 12%	2470
December	1st to 10th	Night	35% 5% 10% 18% 21% 11%	2470
	11th to 20th	Night	38% 5% 6% 17% 15% 18%	3037
	21st to end	Night	34% 7% 9% 14% 21% 15%	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	18% 11% 29% 30% 10% 1	270
	11th to 20th	Day	17% 9% 29% 33% 12% 1	270
	21st to end	Day	19% 9% 36% 23% 12% 1	297
February	1st to 10th	Day	17% 10% 33% 24% 13% 2	270
	11th to 20th	Day	16% 11% 37% 26% 9%	270
	21st to end	Day	16% 11% 39% 28% 4	225
March	1st to 10th	Day	17% 9% 37% 26% 9% 1	270
	11th to 20th	Day	16% 11% 39% 26% 6% 1	261
	21st to end	Day	13% 10% 41% 30% 6%	264
April	1st to 10th	Day	18% 6% 39% 27% 10%	240
	11th to 20th	Day	14% 10% 31% 31% 14%	238
	21st to end	Day	8% 13% 45% 27% 6%	460
May	1st to 10th	Day	9% 8% 43% 31% 8%	603
	11th to 20th	Day	12% 5% 34% 37% 11% 1	625
	21st to end	Day	6% 3 30% 44% 16% 1	679
June	1st to 10th	Day	4 1 15% 44% 33% 3	630
	11th to 20th	Day	3 1 15% 52% 25% 3	630
	21st to end	Day	6% 2 11% 40% 32% 9%	630
July	1st to 10th	Day	5% 2 11% 37% 37% 8%	621
	11th to 20th	Day	4 6% 39% 44% 7%	618
	21st to end	Day	3 1 5% 40% 41% 10%	682
August	1st to 10th	Day	6% 41% 40% 13%	447
	11th to 20th	Day	4 5% 35% 41% 15%	437
	21st to end	Day	6% 1 4 27% 36% 26%	406
September	1st to 10th	Day	11% 4 24% 43% 17%	270
	11th to 20th	Day	7% 2 19% 46% 27%	270
	21st to end	Day	10% 2 7% 15% 43% 23%	270
October	1st to 10th	Day	8% 4 7% 29% 37% 15%	270
	11th to 20th	Day	14% 1 7% 34% 29% 14%	270
	21st to end	Day	13% 7% 21% 32% 21% 6%	297
November	1st to 10th	Day	16% 1 16% 35% 24% 7%	270
	11th to 20th	Day	17% 7% 15% 33% 23% 6%	270
	21st to end	Day	21% 9% 29% 26% 11% 3	270
December	1st to 10th	Day	21% 4 20% 30% 22% 4	270
	11th to 20th	Day	22% 9% 27% 26% 15% 1	270
	21st to end	Day	15% 8% 29% 31% 15% 2	297
January	1st to 10th	Night	19% 6% 27% 37% 10% 1	950
	11th to 20th	Night	20% 6% 31% 36% 7%	900
	21st to end	Night	19% 8% 31% 35% 7%	836
February	1st to 10th	Night	15% 10% 36% 32% 6%	760
	11th to 20th	Night	20% 8% 40% 29% 4	744
	21st to end	Night	15% 10% 47% 25% 3	628
March	1st to 10th	Night	16% 11% 45% 25% 3	618
	11th to 20th	Night	13% 11% 46% 27% 3	564
	21st to end	Night	10% 9% 56% 24% 2	594
April	1st to 10th	Night	9% 7% 58% 24% 3	540
	11th to 20th	Night	11% 9% 51% 26% 3	533
	21st to end	Night	9% 10% 52% 25% 4	540
May	1st to 10th	Night	7% 8% 58% 26% 2	540
	11th to 20th	Night	8% 7% 47% 33% 5%	531
	21st to end	Night	4 3 49% 39% 4	584
June	1st to 10th	Night	2 1 31% 52% 13% 1	540
	11th to 20th	Night	3 1 38% 50% 8%	540
	21st to end	Night	4 1 26% 51% 16% 1	540
July	1st to 10th	Night	6% 2 14% 58% 18%	525
	11th to 20th	Night	2 14% 66% 18%	522
	21st to end	Night	3 1 13% 66% 18% 1	591
August	1st to 10th	Night	1 15% 64% 19% 1	537
	11th to 20th	Night	3 1 13% 60% 21% 1	534
	21st to end	Night	5% 1 9% 53% 30% 2	594
September	1st to 10th	Night	9% 1 10% 49% 28% 3	540
	11th to 20th	Night	11% 1 8% 41% 36% 4	540
	21st to end	Night	11% 12% 42% 29% 5%	540
October	1st to 10th	Night	5% 1 13% 52% 27% 2	540
	11th to 20th	Night	11% 2 23% 47% 17% 1	570
	21st to end	Night	10% 5% 28% 40% 17% 1	792
November	1st to 10th	Night	9% 3 24% 44% 18% 1	740
	11th to 20th	Night	13% 3 24% 43% 16% 1	854
	21st to end	Night	16% 7% 26% 37% 13% 1	950
December	1st to 10th	Night	19% 5% 21% 42% 12% 1	950
	11th to 20th	Night	23% 5% 27% 35% 9% 1	950
	21st to end	Night	16% 7% 28% 38% 11%	1045

Page generated at 2024-03-15 13:01:46. Version ac07

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