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 2026-10-29.

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	9% 5% 2 5% 4 4 4 4 5% 8% 49%	149141
	Night	11% 5% 2 5% 3 3 3 3 5% 8% 53%	143361
Transparency	Day	32% 6% 12% 24% 17% 9%	152973
	Night	29% 6% 14% 24% 17% 11%	147597
Seeing	Day	9% 5% 21% 34% 24% 7%	17169
	Night	11% 5% 30% 40% 12% 1	27066

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% 7% 2 5% 4 2 3 2 3 5% 52%	5289
	11th to 20th	Day	14% 5% 2 5% 3 3 3 2 4 5% 53%	5526
	21st to end	Day	21% 8% 3 5% 3 3 4 3 4 6% 40%	6468
February	1st to 10th	Day	15% 7% 3 6% 4 3 3 3 4 5% 46%	2100
	11th to 20th	Day	14% 7% 3 5% 4 3 3 3 4 5% 49%	2049
	21st to end	Day	14% 6% 2 4 3 3 3 3 4 6% 53%	1730
March	1st to 10th	Day	10% 5% 2 6% 4 3 4 3 6% 7% 50%	4947
	11th to 20th	Day	15% 6% 2 5% 3 3 3 2 3 4 54%	5090
	21st to end	Day	11% 6% 2 5% 3 4 3 3 5% 7% 52%	5583
April	1st to 10th	Day	9% 6% 3 5% 3 3 4 4 5% 8% 49%	2310
	11th to 20th	Day	12% 7% 2 7% 4 4 4 3 5% 6% 44%	2291
	21st to end	Day	10% 6% 3 6% 5% 4 4 4 5% 7% 47%	2567
May	1st to 10th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 8% 37%	7617
	11th to 20th	Day	7% 4 2 6% 4 4 4 4 6% 8% 51%	7627
	21st to end	Day	7% 6% 2 7% 5% 5% 5% 4 7% 9% 42%	8392
June	1st to 10th	Day	4 2 1 5% 4 4 4 5% 7% 10% 54%	2730
	11th to 20th	Day	4 3 1 4 4 5% 5% 4 7% 9% 53%	2730
	21st to end	Day	6% 4 1 5% 6% 5% 6% 5% 7% 10% 45%	2730
July	1st to 10th	Day	6% 5% 2 6% 5% 4 5% 4 6% 10% 46%	7680
	11th to 20th	Day	6% 7% 3 7% 5% 5% 6% 4 7% 11% 39%	7680
	21st to end	Day	4 3 1 4 4 4 4 4 6% 9% 55%	8322
August	1st to 10th	Day	1 1 1 2 2 2 3 4 5% 9% 69%	5545
	11th to 20th	Day	1 2 1 3 3 3 4 5% 7% 12% 60%	5483
	21st to end	Day	3 2 1 4 3 5% 5% 4 7% 11% 55%	5845
September	1st to 10th	Day	9% 6% 2 6% 5% 6% 6% 4 6% 8% 42%	2310
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 4 8% 8% 41%	2310
	21st to end	Day	7% 5% 2 5% 4 4 6% 4 6% 9% 49%	2310
October	1st to 10th	Day	6% 4 2 4 4 3 4 4 5% 6% 57%	2310
	11th to 20th	Day	10% 4 1 5% 3 4 4 3 5% 6% 55%	2252
	21st to end	Day	9% 3 2 4 3 3 3 3 4 5% 61%	2280
November	1st to 10th	Day	11% 6% 2 6% 4 4 3 4 5% 6% 50%	2058
	11th to 20th	Day	12% 6% 2 5% 3 3 3 3 4 6% 52%	1992
	21st to end	Day	15% 7% 2 7% 4 4 4 4 4 5% 45%	1890
December	1st to 10th	Day	31% 10% 3 5% 3 3 2 2 3 5% 34%	3030
	11th to 20th	Day	15% 7% 3 7% 4 4 4 3 5% 5% 44%	3481
	21st to end	Day	10% 5% 2 5% 3 3 4 3 4 6% 55%	4587
January	1st to 10th	Night	16% 7% 2 4 2 2 3 2 3 5% 53%	7634
	11th to 20th	Night	13% 5% 2 5% 3 3 2 2 4 6% 55%	7520
	21st to end	Night	23% 6% 2 6% 3 3 3 3 5% 6% 40%	7746
February	1st to 10th	Night	12% 5% 2 4 4 3 3 3 5% 7% 51%	2520
	11th to 20th	Night	16% 6% 2 5% 2 2 3 2 4 7% 50%	2458
	21st to end	Night	12% 6% 1 4 3 3 4 3 5% 5% 53%	2076
March	1st to 10th	Night	11% 6% 2 5% 4 4 4 3 5% 7% 49%	5130
	11th to 20th	Night	15% 5% 2 5% 3 2 3 2 4 5% 54%	5090
	21st to end	Night	11% 5% 1 4 3 2 3 3 5% 6% 57%	5588
April	1st to 10th	Night	8% 5% 2 5% 4 3 4 4 6% 8% 51%	2310
	11th to 20th	Night	11% 5% 2 5% 3 5% 3 4 6% 7% 50%	2272
	21st to end	Night	10% 7% 2 5% 5% 4 4 4 5% 8% 47%	2048
May	1st to 10th	Night	16% 7% 2 6% 4 4 4 4 6% 8% 39%	5266
	11th to 20th	Night	7% 4 1 4 3 3 4 3 6% 10% 53%	5265
	21st to end	Night	8% 6% 2 6% 4 4 4 4 8% 11% 44%	5793
June	1st to 10th	Night	3 3 1 4 3 2 4 4 5% 9% 64%	1890
	11th to 20th	Night	3 2 1 2 2 2 3 3 5% 9% 65%	1890
	21st to end	Night	4 4 1 3 3 4 4 3 6% 9% 58%	1890
July	1st to 10th	Night	5% 4 2 5% 4 4 4 4 6% 11% 52%	5308
	11th to 20th	Night	5% 5% 2 6% 5% 4 5% 4 7% 11% 46%	5307
	21st to end	Night	4 3 1 4 3 3 4 4 5% 8% 61%	5770
August	1st to 10th	Night	1 1 1 1 1 2 2 4 9% 78%	4621
	11th to 20th	Night	1 2 1 3 3 3 4 4 6% 11% 63%	4583
	21st to end	Night	1 2 1 3 2 3 3 3 5% 11% 67%	5290
September	1st to 10th	Night	7% 5% 2 5% 5% 4 4 4 6% 10% 48%	2310
	11th to 20th	Night	8% 5% 2 4 4 4 5% 4 7% 9% 49%	2310
	21st to end	Night	7% 4 2 5% 2 4 4 3 6% 9% 56%	2310
October	1st to 10th	Night	5% 3 1 3 3 2 4 2 5% 7% 64%	2310
	11th to 20th	Night	9% 4 2 3 3 2 3 2 5% 7% 61%	2346
	21st to end	Night	8% 4 1 3 2 2 3 2 3 5% 65%	2737
November	1st to 10th	Night	9% 6% 2 4 3 3 3 2 4 6% 57%	2460
	11th to 20th	Night	11% 4 1 4 3 3 3 3 4 7% 57%	2624
	21st to end	Night	15% 5% 2 5% 4 3 3 3 4 5% 50%	2730
December	1st to 10th	Night	36% 8% 2 5% 3 2 2 2 3 3 34%	4380
	11th to 20th	Night	12% 6% 2 5% 3 4 4 3 4 6% 50%	4946
	21st to end	Night	9% 5% 2 5% 3 3 3 3 4 6% 58%	6633

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 8% 18% 23% 11%	5290
	11th to 20th	Day	35% 2 4 15% 28% 16%	5526
	21st to end	Day	46% 4 6% 16% 19% 9%	6468
February	1st to 10th	Day	41% 5% 7% 11% 19% 17%	2100
	11th to 20th	Day	38% 5% 8% 18% 19% 13%	2059
	21st to end	Day	33% 5% 8% 19% 21% 14%	1730
March	1st to 10th	Day	32% 6% 8% 20% 13% 21%	4947
	11th to 20th	Day	35% 5% 5% 9% 18% 29%	5090
	21st to end	Day	32% 5% 9% 22% 20% 13%	5585
April	1st to 10th	Day	33% 5% 11% 18% 18% 14%	2310
	11th to 20th	Day	39% 6% 10% 17% 14% 14%	2291
	21st to end	Day	36% 7% 10% 19% 17% 12%	2567
May	1st to 10th	Day	42% 7% 12% 21% 14% 4	7655
	11th to 20th	Day	28% 7% 13% 23% 21% 8%	7631
	21st to end	Day	35% 7% 11% 32% 14% 1	8405
June	1st to 10th	Day	23% 8% 15% 30% 21% 4	2730
	11th to 20th	Day	25% 7% 12% 26% 25% 4	2730
	21st to end	Day	31% 9% 17% 26% 15% 2	2730
July	1st to 10th	Day	32% 7% 21% 34% 5% 1	7616
	11th to 20th	Day	38% 8% 21% 24% 9% 1	7611
	21st to end	Day	24% 6% 16% 36% 17% 1	8140
August	1st to 10th	Day	13% 6% 15% 43% 22% 2	5532
	11th to 20th	Day	16% 6% 24% 43% 9% 1	5519
	21st to end	Day	22% 7% 16% 34% 19% 1	5844
September	1st to 10th	Day	40% 9% 14% 18% 14% 5%	2310
	11th to 20th	Day	37% 10% 14% 21% 15% 3	2310
	21st to end	Day	30% 7% 13% 25% 14% 11%	2310
October	1st to 10th	Day	20% 4 8% 12% 25% 31%	3700
	11th to 20th	Day	26% 5% 9% 19% 16% 24%	3583
	21st to end	Day	22% 3 8% 16% 33% 18%	3618
November	1st to 10th	Day	33% 5% 8% 18% 22% 13%	2058
	11th to 20th	Day	33% 5% 9% 20% 19% 15%	1992
	21st to end	Day	42% 5% 7% 18% 16% 12%	1890
December	1st to 10th	Day	56% 3 6% 13% 16% 6%	3030
	11th to 20th	Day	40% 6% 8% 17% 15% 14%	3479
	21st to end	Day	30% 5% 6% 20% 24% 14%	4587
January	1st to 10th	Night	34% 4 8% 18% 20% 16%	7635
	11th to 20th	Night	33% 2 4 17% 22% 21%	7520
	21st to end	Night	46% 4 6% 15% 18% 11%	7746
February	1st to 10th	Night	33% 6% 8% 16% 17% 20%	2520
	11th to 20th	Night	35% 5% 9% 17% 18% 16%	2458
	21st to end	Night	32% 5% 9% 19% 21% 14%	2076
March	1st to 10th	Night	33% 7% 10% 20% 13% 17%	5130
	11th to 20th	Night	34% 5% 7% 10% 16% 27%	5090
	21st to end	Night	26% 5% 11% 24% 22% 11%	5588
April	1st to 10th	Night	28% 8% 14% 21% 16% 13%	2310
	11th to 20th	Night	30% 8% 14% 18% 14% 15%	2272
	21st to end	Night	34% 7% 14% 18% 17% 10%	2048
May	1st to 10th	Night	42% 7% 13% 20% 13% 5%	5293
	11th to 20th	Night	25% 7% 15% 22% 22% 9%	5266
	21st to end	Night	32% 8% 18% 33% 9%	5805
June	1st to 10th	Night	17% 7% 20% 33% 20% 2	1890
	11th to 20th	Night	16% 6% 14% 33% 26% 4	1890
	21st to end	Night	22% 9% 22% 28% 17% 2	1890
July	1st to 10th	Night	28% 7% 27% 34% 4	5265
	11th to 20th	Night	31% 8% 29% 26% 7%	5256
	21st to end	Night	21% 5% 21% 38% 13% 2	5641
August	1st to 10th	Night	7% 3 20% 48% 21%	4611
	11th to 20th	Night	16% 6% 32% 39% 7%	4613
	21st to end	Night	13% 8% 25% 36% 17% 1	5290
September	1st to 10th	Night	30% 10% 22% 19% 14% 5%	2310
	11th to 20th	Night	29% 9% 17% 27% 15% 3	2310
	21st to end	Night	24% 6% 14% 30% 16% 9%	2310
October	1st to 10th	Night	17% 4 8% 19% 20% 32%	3700
	11th to 20th	Night	18% 4 14% 20% 22% 22%	3741
	21st to end	Night	18% 3 10% 20% 31% 18%	4349
November	1st to 10th	Night	27% 5% 10% 21% 24% 13%	2460
	11th to 20th	Night	29% 6% 12% 19% 20% 15%	2624
	21st to end	Night	36% 5% 8% 20% 19% 12%	2730
December	1st to 10th	Night	57% 3 6% 10% 14% 9%	4380
	11th to 20th	Night	33% 5% 9% 21% 16% 17%	4947
	21st to end	Night	27% 6% 7% 19% 23% 18%	6633

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% 28% 29% 12% 2	330
	11th to 20th	Day	18% 9% 29% 32% 12% 1	330
	21st to end	Day	20% 10% 36% 22% 12% 1	363
February	1st to 10th	Day	15% 9% 31% 26% 15% 3	330
	11th to 20th	Day	16% 12% 35% 27% 10%	330
	21st to end	Day	16% 10% 35% 33% 5% 1	273
March	1st to 10th	Day	16% 10% 36% 28% 9% 1	330
	11th to 20th	Day	14% 11% 41% 26% 8% 1	330
	21st to end	Day	11% 10% 39% 33% 8%	363
April	1st to 10th	Day	14% 9% 39% 29% 8%	330
	11th to 20th	Day	13% 9% 35% 30% 11%	329
	21st to end	Day	9% 13% 44% 29% 5%	587
May	1st to 10th	Day	11% 9% 43% 30% 7%	753
	11th to 20th	Day	10% 7% 35% 36% 10% 1	775
	21st to end	Day	6% 4 30% 44% 15% 1	844
June	1st to 10th	Day	4 2 17% 45% 30% 3	780
	11th to 20th	Day	4 2 16% 51% 23% 4	780
	21st to end	Day	5% 2 12% 42% 30% 8%	780
July	1st to 10th	Day	5% 2 11% 37% 36% 8%	771
	11th to 20th	Day	4 1 8% 41% 39% 7%	768
	21st to end	Day	2 2 6% 40% 40% 10%	846
August	1st to 10th	Day	1 5% 37% 41% 16%	567
	11th to 20th	Day	3 5% 37% 40% 15%	557
	21st to end	Day	4 1 4 25% 37% 28%	523
September	1st to 10th	Day	10% 1 4 26% 43% 17%	360
	11th to 20th	Day	7% 2 18% 48% 26%	360
	21st to end	Day	8% 2 8% 16% 43% 24%	360
October	1st to 10th	Day	7% 4 7% 29% 36% 17%	360
	11th to 20th	Day	12% 2 7% 33% 33% 13%	360
	21st to end	Day	12% 6% 20% 32% 24% 7%	387
November	1st to 10th	Day	14% 2 20% 34% 23% 7%	330
	11th to 20th	Day	14% 6% 17% 34% 23% 6%	330
	21st to end	Day	20% 10% 27% 27% 13% 3	330
December	1st to 10th	Day	23% 6% 19% 29% 20% 3	330
	11th to 20th	Day	22% 8% 24% 26% 19% 2	330
	21st to end	Day	13% 7% 27% 31% 20% 2	363
January	1st to 10th	Night	20% 6% 27% 37% 10% 1	1050
	11th to 20th	Night	19% 6% 33% 36% 6%	994
	21st to end	Night	19% 9% 31% 35% 6%	924
February	1st to 10th	Night	14% 9% 37% 34% 5%	840
	11th to 20th	Night	20% 8% 40% 28% 4	824
	21st to end	Night	15% 10% 46% 27% 3	692
March	1st to 10th	Night	17% 11% 45% 24% 3	683
	11th to 20th	Night	12% 13% 46% 27% 3	630
	21st to end	Night	10% 10% 56% 23% 2	693
April	1st to 10th	Night	10% 9% 56% 23% 3	630
	11th to 20th	Night	11% 10% 52% 25% 3	623
	21st to end	Night	10% 11% 51% 24% 4	630
May	1st to 10th	Night	9% 10% 56% 23% 1	630
	11th to 20th	Night	8% 8% 48% 31% 5%	621
	21st to end	Night	5% 4 50% 38% 4	683
June	1st to 10th	Night	3 2 33% 49% 12%	630
	11th to 20th	Night	4 1 38% 49% 8%	630
	21st to end	Night	3 1 27% 52% 15% 1	630
July	1st to 10th	Night	7% 2 14% 59% 17%	615
	11th to 20th	Night	3 1 17% 63% 16%	612
	21st to end	Night	4 1 14% 64% 17% 1	690
August	1st to 10th	Night	1 14% 64% 19% 1	627
	11th to 20th	Night	3 1 15% 60% 20% 1	624
	21st to end	Night	4 1 9% 53% 30% 3	693
September	1st to 10th	Night	9% 1 11% 49% 27% 4	630
	11th to 20th	Night	10% 1 9% 43% 35% 3	630
	21st to end	Night	10% 13% 43% 29% 4	630
October	1st to 10th	Night	5% 2 13% 50% 29% 2	630
	11th to 20th	Night	10% 2 23% 47% 18% 1	666
	21st to end	Night	9% 4 29% 40% 17% 1	913
November	1st to 10th	Night	9% 4 25% 44% 17% 1	820
	11th to 20th	Night	12% 2 25% 43% 16% 1	944
	21st to end	Night	16% 8% 26% 37% 13% 1	1050
December	1st to 10th	Night	22% 5% 21% 40% 11% 1	1050
	11th to 20th	Night	21% 6% 26% 37% 10%	1050
	21st to end	Night	15% 6% 28% 39% 11%	1155

Page generated at 2026-10-26 03:37:53. Version ac07

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