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 2025-07-06.

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% 4 4 4 4 5% 7% 49%	120226
	Night	11% 5% 2 4 3 3 3 3 5% 7% 53%	118828
Transparency	Day	32% 6% 11% 22% 18% 11%	124100
	Night	29% 6% 13% 22% 18% 12%	123085
Seeing	Day	10% 5% 22% 34% 23% 6%	15430
	Night	12% 5% 30% 40% 12% 1	25416

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% 6% 2 5% 3 3 3 2 4 5% 50%	4077
	11th to 20th	Day	16% 4 2 4 3 3 3 3 5% 7% 52%	4240
	21st to end	Day	22% 7% 3 6% 4 3 4 4 5% 6% 37%	4994
February	1st to 10th	Day	15% 7% 3 6% 5% 3 3 3 5% 5% 46%	2000
	11th to 20th	Day	15% 7% 3 5% 4 3 3 2 4 5% 49%	1949
	21st to end	Day	14% 6% 2 4 3 3 3 4 4 6% 51%	1650
March	1st to 10th	Day	10% 5% 2 6% 4 3 4 3 6% 7% 50%	4840
	11th to 20th	Day	15% 6% 2 5% 3 3 3 2 3 4 54%	4980
	21st to end	Day	11% 6% 2 5% 3 4 3 3 5% 7% 51%	5462
April	1st to 10th	Day	9% 6% 3 5% 3 3 4 4 5% 8% 50%	2200
	11th to 20th	Day	12% 7% 2 7% 4 4 4 3 5% 6% 45%	2181
	21st to end	Day	10% 6% 3 6% 4 4 4 4 4 6% 48%	2445
May	1st to 10th	Day	12% 6% 3 8% 6% 5% 5% 4 6% 8% 37%	5862
	11th to 20th	Day	7% 4 2 5% 4 4 4 3 5% 7% 56%	5862
	21st to end	Day	5% 5% 2 6% 5% 5% 5% 4 7% 9% 47%	6434
June	1st to 10th	Day	3 2 1 4 4 4 4 5% 7% 9% 56%	2600
	11th to 20th	Day	3 3 1 4 4 5% 5% 4 7% 9% 55%	2600
	21st to end	Day	6% 4 1 5% 6% 6% 6% 5% 7% 10% 43%	2600
July	1st to 10th	Day	6% 5% 2 6% 5% 4 5% 4 7% 8% 49%	4186
	11th to 20th	Day	5% 6% 3 7% 6% 6% 5% 4 7% 10% 41%	4120
	21st to end	Day	6% 5% 2 6% 6% 5% 5% 5% 7% 10% 44%	4450
August	1st to 10th	Day	1 1 2 3 2 3 3 4 8% 73%	3785
	11th to 20th	Day	2 2 1 3 3 3 5% 5% 8% 11% 56%	3726
	21st to end	Day	4 3 2 5% 4 6% 6% 5% 8% 12% 44%	4021
September	1st to 10th	Day	10% 6% 3 7% 5% 6% 7% 4 6% 7% 40%	2090
	11th to 20th	Day	10% 5% 2 7% 5% 5% 6% 4 8% 8% 40%	2090
	21st to end	Day	7% 5% 2 5% 4 4 6% 4 6% 9% 50%	2090
October	1st to 10th	Day	6% 4 2 4 4 4 4 4 6% 6% 56%	2090
	11th to 20th	Day	10% 4 1 5% 3 4 4 3 5% 6% 54%	2038
	21st to end	Day	9% 3 2 4 3 3 3 3 3 5% 62%	2090
November	1st to 10th	Day	11% 6% 2 6% 4 4 3 4 5% 6% 48%	1958
	11th to 20th	Day	13% 6% 2 5% 3 3 3 3 4 6% 51%	1897
	21st to end	Day	15% 7% 2 6% 4 3 4 4 4 5% 46%	1800
December	1st to 10th	Day	31% 11% 3 5% 3 3 2 2 3 5% 33%	2940
	11th to 20th	Day	14% 7% 3 7% 4 4 4 3 5% 5% 44%	3391
	21st to end	Day	10% 5% 2 5% 3 3 4 3 4 6% 55%	4488
January	1st to 10th	Night	20% 6% 2 5% 2 2 3 2 4 5% 50%	5888
	11th to 20th	Night	14% 4 1 4 3 3 3 3 5% 7% 54%	5782
	21st to end	Night	27% 6% 2 6% 3 3 3 2 5% 6% 37%	5984
February	1st to 10th	Night	12% 5% 2 4 4 4 3 3 5% 7% 50%	2400
	11th to 20th	Night	16% 6% 2 5% 3 3 3 2 4 6% 49%	2338
	21st to end	Night	12% 7% 1 4 3 3 4 3 5% 5% 51%	1980
March	1st to 10th	Night	11% 6% 2 5% 4 4 4 3 5% 7% 49%	5017
	11th to 20th	Night	15% 6% 2 5% 3 2 3 2 4 5% 54%	4980
	21st to end	Night	12% 5% 1 4 3 2 3 3 5% 6% 56%	5467
April	1st to 10th	Night	7% 5% 2 4 4 3 4 4 6% 9% 52%	2200
	11th to 20th	Night	10% 5% 2 5% 3 5% 3 4 6% 7% 51%	2163
	21st to end	Night	9% 7% 2 5% 5% 4 4 4 5% 8% 48%	1950
May	1st to 10th	Night	13% 7% 2 6% 4 4 4 4 6% 8% 42%	4053
	11th to 20th	Night	7% 4 1 4 3 3 3 3 6% 9% 58%	4053
	21st to end	Night	7% 6% 2 6% 4 4 4 4 7% 11% 46%	4443
June	1st to 10th	Night	2 2 1 3 3 2 4 3 5% 9% 66%	1800
	11th to 20th	Night	3 2 1 2 2 2 3 3 5% 9% 66%	1800
	21st to end	Night	4 5% 1 3 3 4 4 3 6% 9% 57%	1800
July	1st to 10th	Night	5% 3 1 3 3 4 4 4 6% 11% 56%	2895
	11th to 20th	Night	4 4 2 6% 5% 4 5% 4 7% 11% 50%	2850
	21st to end	Night	5% 3 1 5% 3 4 5% 4 7% 11% 53%	3098
August	1st to 10th	Night	1 1 1 1 1 2 2 3 6% 82%	3151
	11th to 20th	Night	1 1 1 3 3 3 4 4 7% 12% 61%	3113
	21st to end	Night	2 2 1 4 2 3 4 3 6% 11% 62%	3638
September	1st to 10th	Night	7% 5% 2 6% 5% 4 4 4 6% 9% 48%	2090
	11th to 20th	Night	8% 5% 2 5% 4 4 5% 4 7% 8% 48%	2090
	21st to end	Night	7% 4 2 5% 2 3 3 2 5% 8% 58%	2090
October	1st to 10th	Night	5% 3 1 3 2 3 4 2 5% 7% 65%	2090
	11th to 20th	Night	10% 4 2 4 3 2 2 2 5% 7% 59%	2122
	21st to end	Night	9% 4 1 3 2 2 3 2 3 5% 66%	2508
November	1st to 10th	Night	9% 6% 2 4 4 3 3 2 4 7% 55%	2340
	11th to 20th	Night	11% 4 1 4 3 3 3 3 4 7% 56%	2499
	21st to end	Night	15% 5% 2 4 4 3 3 3 5% 5% 51%	2600
December	1st to 10th	Night	36% 8% 2 5% 3 2 2 2 3 3 34%	4250
	11th to 20th	Night	12% 6% 2 5% 3 4 4 3 4 6% 50%	4816
	21st to end	Night	9% 5% 2 5% 3 3 3 3 4 6% 58%	6490

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	37% 4 6% 16% 24% 12%	4078
	11th to 20th	Day	34% 3 5% 20% 25% 14%	4240
	21st to end	Day	48% 4 5% 14% 18% 11%	4994
February	1st to 10th	Day	42% 5% 7% 11% 19% 17%	2000
	11th to 20th	Day	38% 5% 8% 17% 19% 13%	1959
	21st to end	Day	34% 5% 8% 19% 20% 14%	1650
March	1st to 10th	Day	32% 6% 8% 20% 12% 21%	4840
	11th to 20th	Day	35% 5% 5% 9% 18% 29%	4980
	21st to end	Day	32% 5% 9% 22% 19% 13%	5464
April	1st to 10th	Day	32% 5% 11% 18% 19% 15%	2200
	11th to 20th	Day	38% 5% 10% 17% 15% 15%	2181
	21st to end	Day	35% 7% 8% 19% 18% 13%	2445
May	1st to 10th	Day	41% 8% 11% 19% 15% 5%	5900
	11th to 20th	Day	25% 7% 12% 23% 22% 11%	5866
	21st to end	Day	30% 8% 10% 35% 16% 1	6447
June	1st to 10th	Day	21% 8% 15% 31% 22% 4	2600
	11th to 20th	Day	24% 7% 12% 27% 26% 4	2600
	21st to end	Day	32% 9% 18% 26% 13% 2	2600
July	1st to 10th	Day	30% 8% 16% 37% 8% 1	4122
	11th to 20th	Day	38% 7% 17% 23% 13% 2	4051
	21st to end	Day	32% 9% 20% 28% 9% 1	4310
August	1st to 10th	Day	12% 5% 13% 42% 26% 2	3772
	11th to 20th	Day	19% 8% 25% 37% 10% 1	3762
	21st to end	Day	29% 10% 18% 26% 16% 2	4020
September	1st to 10th	Day	42% 10% 14% 17% 13% 5%	2090
	11th to 20th	Day	39% 11% 13% 18% 16% 4	2090
	21st to end	Day	30% 8% 13% 22% 15% 12%	2090
October	1st to 10th	Day	20% 4 8% 12% 24% 32%	3480
	11th to 20th	Day	26% 6% 9% 18% 16% 25%	3369
	21st to end	Day	22% 3 8% 16% 33% 18%	3428
November	1st to 10th	Day	35% 5% 8% 19% 21% 11%	1958
	11th to 20th	Day	34% 5% 9% 19% 19% 14%	1897
	21st to end	Day	40% 5% 7% 18% 17% 13%	1800
December	1st to 10th	Day	56% 3 6% 13% 17% 6%	2940
	11th to 20th	Day	40% 6% 8% 17% 15% 14%	3389
	21st to end	Day	30% 5% 6% 20% 24% 15%	4488
January	1st to 10th	Night	37% 5% 6% 15% 20% 18%	5888
	11th to 20th	Night	32% 3 5% 19% 22% 19%	5782
	21st to end	Night	48% 4 6% 12% 18% 12%	5984
February	1st to 10th	Night	34% 6% 8% 15% 17% 20%	2400
	11th to 20th	Night	36% 5% 9% 17% 18% 16%	2338
	21st to end	Night	33% 5% 9% 19% 20% 14%	1980
March	1st to 10th	Night	32% 7% 10% 21% 13% 18%	5017
	11th to 20th	Night	35% 5% 7% 10% 16% 27%	4980
	21st to end	Night	26% 5% 12% 24% 22% 11%	5467
April	1st to 10th	Night	27% 8% 13% 21% 17% 14%	2200
	11th to 20th	Night	30% 8% 14% 18% 15% 16%	2163
	21st to end	Night	34% 8% 13% 18% 18% 10%	1950
May	1st to 10th	Night	37% 8% 14% 20% 15% 6%	4080
	11th to 20th	Night	21% 7% 15% 20% 25% 11%	4054
	21st to end	Night	29% 8% 17% 33% 11% 1	4452
June	1st to 10th	Night	15% 7% 20% 35% 21% 2	1800
	11th to 20th	Night	15% 6% 14% 34% 27% 4	1800
	21st to end	Night	23% 9% 23% 28% 15% 2	1800
July	1st to 10th	Night	21% 8% 25% 39% 6%	2850
	11th to 20th	Night	29% 8% 27% 25% 11%	2796
	21st to end	Night	24% 8% 28% 32% 7%	2999
August	1st to 10th	Night	6% 4 15% 49% 26% 1	3141
	11th to 20th	Night	16% 7% 32% 37% 8%	3143
	21st to end	Night	16% 10% 27% 33% 13% 1	3638
September	1st to 10th	Night	32% 10% 21% 18% 14% 5%	2090
	11th to 20th	Night	31% 10% 15% 25% 16% 3	2090
	21st to end	Night	24% 6% 13% 28% 17% 10%	2090
October	1st to 10th	Night	16% 4 8% 19% 20% 33%	3480
	11th to 20th	Night	19% 4 14% 19% 22% 23%	3517
	21st to end	Night	18% 3 11% 19% 31% 18%	4120
November	1st to 10th	Night	28% 6% 10% 21% 23% 11%	2340
	11th to 20th	Night	29% 6% 12% 18% 21% 15%	2499
	21st to end	Night	35% 5% 8% 21% 18% 13%	2600
December	1st to 10th	Night	57% 3 6% 10% 14% 9%	4250
	11th to 20th	Night	33% 5% 9% 21% 15% 17%	4817
	21st to end	Night	27% 6% 7% 19% 23% 18%	6490

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% 11% 29% 29% 10% 1	300
	11th to 20th	Day	18% 10% 30% 31% 11% 1	300
	21st to end	Day	20% 10% 36% 22% 11% 1	330
February	1st to 10th	Day	16% 9% 32% 25% 15% 3	300
	11th to 20th	Day	17% 12% 37% 25% 9%	300
	21st to end	Day	18% 10% 36% 30% 5%	249
March	1st to 10th	Day	17% 10% 37% 26% 9% 1	300
	11th to 20th	Day	15% 12% 41% 26% 6% 1	300
	21st to end	Day	12% 11% 41% 30% 6%	330
April	1st to 10th	Day	14% 9% 40% 27% 9%	300
	11th to 20th	Day	12% 10% 34% 31% 12%	299
	21st to end	Day	9% 12% 45% 28% 5%	545
May	1st to 10th	Day	10% 9% 44% 29% 8%	703
	11th to 20th	Day	10% 7% 34% 37% 10% 1	725
	21st to end	Day	6% 4 31% 44% 14% 1	789
June	1st to 10th	Day	3 1 17% 45% 30% 3	730
	11th to 20th	Day	4 2 16% 51% 23% 3	730
	21st to end	Day	5% 2 12% 41% 32% 9%	730
July	1st to 10th	Day	6% 2 11% 36% 36% 8%	697
	11th to 20th	Day	4 1 7% 39% 43% 7%	668
	21st to end	Day	3 2 6% 40% 40% 10%	736
August	1st to 10th	Day	6% 39% 40% 16%	487
	11th to 20th	Day	3 5% 36% 40% 15%	477
	21st to end	Day	5% 1 4 26% 36% 27%	445
September	1st to 10th	Day	11% 1 5% 27% 41% 16%	300
	11th to 20th	Day	8% 2 18% 44% 27%	300
	21st to end	Day	9% 2 7% 16% 42% 24%	300
October	1st to 10th	Day	7% 4 8% 29% 37% 16%	300
	11th to 20th	Day	13% 2 7% 34% 30% 14%	300
	21st to end	Day	12% 6% 21% 32% 23% 7%	330
November	1st to 10th	Day	15% 2 20% 34% 22% 6%	300
	11th to 20th	Day	15% 6% 17% 33% 22% 6%	300
	21st to end	Day	20% 10% 28% 26% 13% 3	300
December	1st to 10th	Day	22% 6% 20% 28% 21% 3	300
	11th to 20th	Day	21% 9% 25% 27% 17% 1	300
	21st to end	Day	14% 8% 28% 31% 18% 2	330
January	1st to 10th	Night	20% 6% 27% 36% 10% 1	1000
	11th to 20th	Night	19% 6% 32% 36% 6%	947
	21st to end	Night	20% 8% 31% 35% 6%	880
February	1st to 10th	Night	15% 10% 36% 33% 5%	800
	11th to 20th	Night	20% 9% 40% 28% 3	784
	21st to end	Night	16% 10% 46% 25% 3	660
March	1st to 10th	Night	16% 12% 45% 24% 3	650
	11th to 20th	Night	12% 12% 46% 27% 3	600
	21st to end	Night	10% 10% 56% 23% 2	660
April	1st to 10th	Night	9% 9% 57% 23% 3	600
	11th to 20th	Night	10% 10% 52% 26% 3	593
	21st to end	Night	10% 11% 51% 24% 4	600
May	1st to 10th	Night	8% 10% 56% 24% 2	600
	11th to 20th	Night	8% 8% 48% 32% 5%	591
	21st to end	Night	4 4 50% 38% 4	650
June	1st to 10th	Night	2 2 33% 51% 12% 1	600
	11th to 20th	Night	3 1 39% 49% 8%	600
	21st to end	Night	4 2 26% 52% 16% 1	600
July	1st to 10th	Night	7% 2 14% 59% 18% 1	570
	11th to 20th	Night	3 14% 65% 18%	552
	21st to end	Night	4 1 13% 65% 17% 1	624
August	1st to 10th	Night	1 14% 64% 19% 1	567
	11th to 20th	Night	3 1 14% 60% 20% 1	564
	21st to end	Night	4 1 9% 52% 31% 2	627
September	1st to 10th	Night	9% 1 10% 48% 28% 4	570
	11th to 20th	Night	11% 1 9% 41% 36% 3	570
	21st to end	Night	11% 12% 42% 30% 5%	570
October	1st to 10th	Night	5% 1 13% 51% 28% 2	570
	11th to 20th	Night	10% 1 23% 48% 16% 1	602
	21st to end	Night	10% 5% 28% 40% 17% 1	836
November	1st to 10th	Night	9% 4 25% 43% 17% 1	780
	11th to 20th	Night	13% 2 24% 43% 16% 1	899
	21st to end	Night	16% 7% 26% 38% 13% 1	1000
December	1st to 10th	Night	21% 5% 21% 41% 12% 1	1000
	11th to 20th	Night	22% 6% 27% 36% 9% 1	1000
	21st to end	Night	16% 7% 28% 39% 11%	1100

Page generated at 2025-07-03 00:30:17. Version ac07

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