Escure Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Escure Ranch clear sky chart from 2005-11-06 to 2025-06-10.

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	8% 7% 3 6% 4 4 4 4 5% 6% 48%	122964
	Night	11% 8% 3 7% 4 4 4 4 5% 6% 43%	123964
Transparency	Day	36% 6% 11% 22% 17% 8%	122732
	Night	41% 6% 11% 21% 15% 6%	123839
Seeing	Day	12% 8% 22% 27% 22% 10%	14960
	Night	15% 6% 21% 35% 21% 3	24466

By Month

Percentage Cloud Cover NW (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% 17% 9% 15% 7% 5% 5% 4 5% 4 13%	3639
	11th to 20th	Day	14% 10% 4 10% 6% 5% 5% 4 6% 6% 30%	3616
	21st to end	Day	17% 13% 4 9% 4 4 4 3 4 4 34%	4004
February	1st to 10th	Day	16% 13% 5% 9% 5% 5% 6% 4 5% 6% 27%	1650
	11th to 20th	Day	14% 15% 4 10% 6% 5% 5% 4 5% 5% 29%	1865
	21st to end	Day	11% 14% 4 8% 6% 5% 4 4 4 6% 33%	1650
March	1st to 10th	Day	6% 8% 3 6% 6% 6% 8% 5% 8% 9% 36%	4518
	11th to 20th	Day	8% 8% 3 8% 4 5% 5% 4 6% 7% 44%	4670
	21st to end	Day	11% 10% 4 10% 6% 5% 6% 4 7% 9% 27%	5969
April	1st to 10th	Day	9% 9% 3 8% 6% 5% 7% 5% 7% 9% 32%	2400
	11th to 20th	Day	7% 7% 3 7% 6% 5% 5% 4 6% 7% 43%	2402
	21st to end	Day	9% 6% 2 7% 5% 4 5% 4 6% 8% 44%	2600
May	1st to 10th	Day	7% 5% 2 5% 3 3 4 4 6% 8% 55%	6222
	11th to 20th	Day	8% 6% 2 7% 5% 5% 5% 4 6% 6% 46%	6277
	21st to end	Day	6% 5% 2 6% 4 5% 5% 4 5% 7% 50%	6903
June	1st to 10th	Day	11% 6% 2 6% 4 4 4 3 5% 7% 46%	2789
	11th to 20th	Day	8% 6% 2 5% 4 3 4 4 6% 8% 50%	2660
	21st to end	Day	5% 3 2 4 3 3 3 3 5% 7% 63%	2660
July	1st to 10th	Day	1 1 1 2 2 1 2 2 3 4 82%	4420
	11th to 20th	Day	1 1 2 2 2 2 2 3 3 82%	4420
	21st to end	Day	1 1 1 2 2 2 2 2 3 5% 79%	4790
August	1st to 10th	Day	3 2 1 3 2 3 2 2 3 5% 74%	4401
	11th to 20th	Day	2 2 1 3 2 2 3 2 5% 7% 71%	4157
	21st to end	Day	3 3 1 3 2 3 3 4 5% 6% 67%	4180
September	1st to 10th	Day	3 2 1 3 2 2 2 3 4 6% 72%	2280
	11th to 20th	Day	5% 4 1 5% 4 4 4 3 7% 7% 55%	2192
	21st to end	Day	5% 4 2 6% 4 4 5% 4 5% 8% 54%	2090
October	1st to 10th	Day	5% 4 2 4 3 3 3 3 4 8% 61%	3318
	11th to 20th	Day	6% 5% 2 5% 5% 5% 5% 4 7% 8% 47%	3016
	21st to end	Day	11% 7% 3 6% 4 4 5% 4 6% 7% 44%	3101
November	1st to 10th	Day	15% 8% 3 7% 5% 5% 4 5% 6% 8% 34%	1764
	11th to 20th	Day	17% 12% 5% 8% 6% 5% 4 4 5% 6% 28%	1699
	21st to end	Day	13% 14% 5% 12% 7% 5% 5% 4 6% 5% 24%	1600
December	1st to 10th	Day	12% 10% 4 11% 6% 6% 7% 4 6% 7% 27%	2327
	11th to 20th	Day	19% 16% 6% 14% 7% 6% 5% 3 4 4 15%	2711
	21st to end	Day	19% 14% 6% 12% 5% 5% 5% 4 6% 6% 18%	4004
January	1st to 10th	Night	23% 16% 7% 12% 6% 5% 5% 3 5% 4 14%	6306
	11th to 20th	Night	13% 9% 4 9% 4 5% 5% 4 6% 6% 35%	6282
	21st to end	Night	14% 12% 4 9% 4 4 4 3 5% 6% 35%	6952
February	1st to 10th	Night	16% 15% 4 8% 5% 5% 4 4 5% 6% 28%	2749
	11th to 20th	Night	13% 11% 3 9% 5% 4 4 4 5% 7% 34%	2421
	21st to end	Night	12% 11% 4 8% 6% 5% 4 4 5% 7% 34%	1980
March	1st to 10th	Night	7% 7% 3 7% 4 5% 6% 5% 7% 8% 42%	5376
	11th to 20th	Night	9% 10% 4 7% 4 4 4 3 5% 6% 45%	5324
	21st to end	Night	9% 9% 4 9% 7% 7% 7% 5% 9% 9% 25%	5006
April	1st to 10th	Night	11% 10% 3 7% 6% 5% 4 5% 6% 9% 35%	2000
	11th to 20th	Night	8% 8% 3 7% 5% 5% 3 5% 6% 5% 46%	1948
	21st to end	Night	9% 6% 3 7% 5% 5% 5% 5% 6% 8% 43%	1800
May	1st to 10th	Night	6% 5% 2 5% 3 4 5% 3 5% 6% 55%	3738
	11th to 20th	Night	9% 7% 3 7% 5% 4 5% 4 5% 7% 43%	3616
	21st to end	Night	7% 5% 2 5% 4 4 4 3 6% 8% 52%	3972
June	1st to 10th	Night	9% 6% 3 5% 5% 4 4 3 5% 7% 50%	1595
	11th to 20th	Night	10% 5% 2 5% 6% 4 5% 4 6% 5% 50%	1520
	21st to end	Night	6% 4 2 4 4 4 4 3 6% 7% 57%	1520
July	1st to 10th	Night	1 1 1 2 1 1 2 2 3 4 82%	2540
	11th to 20th	Night	2 1 1 1 1 2 2 3 4 82%	2540
	21st to end	Night	2 2 1 2 1 1 2 2 2 4 80%	2762
August	1st to 10th	Night	4 2 1 3 1 2 2 3 4 6% 71%	2529
	11th to 20th	Night	2 2 1 4 3 3 4 4 4 5% 66%	2675
	21st to end	Night	2 2 1 3 3 3 3 3 4 6% 70%	3494
September	1st to 10th	Night	3 2 1 2 3 2 4 3 3 6% 70%	1900
	11th to 20th	Night	5% 4 1 5% 5% 4 4 4 5% 7% 57%	1987
	21st to end	Night	7% 4 2 5% 3 3 4 4 5% 9% 54%	2090
October	1st to 10th	Night	6% 3 1 4 3 3 3 3 5% 6% 64%	3659
	11th to 20th	Night	9% 4 2 5% 4 4 4 4 6% 8% 51%	3917
	21st to end	Night	11% 6% 2 6% 4 4 4 4 5% 7% 47%	4457
November	1st to 10th	Night	16% 9% 3 8% 5% 4 4 4 6% 7% 34%	2535
	11th to 20th	Night	16% 9% 3 9% 5% 5% 5% 4 5% 6% 32%	2700
	21st to end	Night	15% 10% 4 8% 6% 5% 5% 5% 6% 5% 31%	2800
December	1st to 10th	Night	8% 8% 3 8% 6% 6% 6% 5% 8% 7% 35%	4814
	11th to 20th	Night	20% 16% 7% 13% 7% 5% 5% 4 5% 6% 13%	5508
	21st to end	Night	19% 14% 5% 13% 6% 5% 4 3 5% 5% 21%	6952

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	72% 9% 11% 8% 1	3639
	11th to 20th	Day	52% 9% 16% 18% 5% 1	3640
	21st to end	Day	55% 5% 13% 19% 8%	4004
February	1st to 10th	Day	57% 9% 15% 12% 6% 1	1650
	11th to 20th	Day	56% 8% 13% 17% 6%	1874
	21st to end	Day	52% 8% 11% 19% 9% 1	1650
March	1st to 10th	Day	41% 6% 11% 24% 16% 1	4518
	11th to 20th	Day	39% 5% 12% 31% 12%	4670
	21st to end	Day	51% 9% 15% 18% 7%	5969
April	1st to 10th	Day	46% 8% 16% 21% 9% 1	2400
	11th to 20th	Day	39% 6% 14% 23% 14% 3	2402
	21st to end	Day	37% 7% 13% 26% 15% 2	2600
May	1st to 10th	Day	27% 4 8% 27% 29% 4	6222
	11th to 20th	Day	35% 6% 11% 28% 17% 3	6280
	21st to end	Day	31% 6% 14% 31% 16% 3	6904
June	1st to 10th	Day	38% 6% 8% 23% 20% 4	2789
	11th to 20th	Day	31% 5% 14% 27% 19% 5%	2660
	21st to end	Day	22% 5% 9% 29% 28% 8%	2660
July	1st to 10th	Day	9% 2 4 15% 27% 42%	4351
	11th to 20th	Day	9% 2 4 10% 27% 47%	4345
	21st to end	Day	10% 2 5% 17% 35% 30%	4639
August	1st to 10th	Day	15% 3 4 15% 37% 27%	4384
	11th to 20th	Day	14% 4 7% 36% 30% 9%	4199
	21st to end	Day	18% 4 10% 28% 31% 9%	4179
September	1st to 10th	Day	15% 4 8% 30% 29% 14%	2280
	11th to 20th	Day	27% 5% 13% 24% 23% 8%	2192
	21st to end	Day	28% 6% 16% 29% 16% 4	2090
October	1st to 10th	Day	24% 3 11% 35% 24% 3	3318
	11th to 20th	Day	34% 6% 18% 28% 14% 1	3016
	21st to end	Day	39% 7% 12% 29% 12% 2	3101
November	1st to 10th	Day	46% 8% 16% 22% 6% 1	1764
	11th to 20th	Day	57% 7% 15% 16% 3 1	1699
	21st to end	Day	58% 11% 15% 11% 4 1	1600
December	1st to 10th	Day	53% 9% 21% 14% 3	2327
	11th to 20th	Day	72% 8% 9% 10% 1	2713
	21st to end	Day	65% 8% 15% 10% 2	4004
January	1st to 10th	Night	71% 8% 10% 9% 1	6306
	11th to 20th	Night	48% 7% 19% 18% 8%	6320
	21st to end	Night	50% 6% 13% 21% 9%	6952
February	1st to 10th	Night	57% 6% 15% 15% 6% 1	2749
	11th to 20th	Night	50% 7% 16% 18% 8% 1	2423
	21st to end	Night	49% 7% 14% 19% 9% 1	1980
March	1st to 10th	Night	37% 6% 9% 27% 20% 1	5376
	11th to 20th	Night	41% 5% 8% 30% 16%	5325
	21st to end	Night	50% 9% 13% 23% 5% 1	5006
April	1st to 10th	Night	44% 8% 12% 24% 12% 1	2000
	11th to 20th	Night	39% 7% 9% 25% 17% 4	1948
	21st to end	Night	38% 7% 12% 20% 19% 4	1800
May	1st to 10th	Night	28% 5% 7% 24% 30% 5%	3735
	11th to 20th	Night	38% 7% 8% 25% 20% 3	3616
	21st to end	Night	29% 7% 14% 32% 17% 2	3972
June	1st to 10th	Night	34% 5% 8% 24% 23% 6%	1595
	11th to 20th	Night	34% 6% 7% 27% 21% 5%	1520
	21st to end	Night	26% 4 9% 23% 27% 11%	1520
July	1st to 10th	Night	9% 2 4 13% 25% 48%	2500
	11th to 20th	Night	8% 2 4 9% 19% 58%	2492
	21st to end	Night	10% 2 2 13% 30% 42%	2674
August	1st to 10th	Night	15% 2 5% 9% 37% 31%	2521
	11th to 20th	Night	19% 4 5% 24% 34% 14%	2699
	21st to end	Night	17% 3 7% 28% 29% 17%	3494
September	1st to 10th	Night	16% 4 6% 24% 30% 20%	1900
	11th to 20th	Night	26% 5% 9% 23% 25% 11%	1987
	21st to end	Night	27% 5% 10% 30% 20% 8%	2090
October	1st to 10th	Night	22% 4 9% 31% 32% 2	3659
	11th to 20th	Night	32% 5% 15% 23% 24% 2	3917
	21st to end	Night	37% 5% 9% 33% 15% 2	4457
November	1st to 10th	Night	49% 7% 14% 23% 6% 1	2535
	11th to 20th	Night	53% 7% 16% 17% 6% 1	2700
	21st to end	Night	52% 9% 17% 17% 6%	2800
December	1st to 10th	Night	43% 11% 21% 21% 4	4814
	11th to 20th	Night	71% 8% 12% 7% 1	5505
	21st to end	Night	64% 7% 12% 13% 4	6952

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	28% 6% 29% 21% 13% 5%	200
	11th to 20th	Day	28% 5% 17% 27% 19% 5%	200
	21st to end	Day	27% 5% 20% 28% 16% 4	220
February	1st to 10th	Day	22% 7% 30% 26% 12% 3	250
	11th to 20th	Day	24% 12% 23% 23% 15% 3	451
	21st to end	Day	19% 12% 26% 26% 15% 3	414
March	1st to 10th	Day	17% 12% 31% 20% 17% 4	500
	11th to 20th	Day	13% 11% 23% 25% 20% 8%	500
	21st to end	Day	15% 13% 28% 26% 14% 3	550
April	1st to 10th	Day	15% 13% 25% 25% 16% 6%	500
	11th to 20th	Day	11% 14% 33% 23% 16% 5%	492
	21st to end	Day	10% 10% 27% 27% 19% 7%	500
May	1st to 10th	Day	7% 10% 22% 32% 22% 6%	503
	11th to 20th	Day	16% 5% 23% 26% 16% 14%	528
	21st to end	Day	9% 6% 23% 25% 23% 15%	573
June	1st to 10th	Day	12% 6% 22% 22% 25% 13%	527
	11th to 20th	Day	10% 10% 29% 29% 14% 8%	490
	21st to end	Day	4 5% 20% 29% 29% 12%	490
July	1st to 10th	Day	3 2 20% 31% 38% 7%	486
	11th to 20th	Day	1 3 18% 36% 31% 11%	484
	21st to end	Day	1 3 16% 31% 31% 17%	531
August	1st to 10th	Day	3 4 15% 29% 32% 17%	487
	11th to 20th	Day	3 1 14% 28% 34% 19%	477
	21st to end	Day	5% 6% 20% 25% 26% 18%	539
September	1st to 10th	Day	5% 3 19% 28% 27% 18%	490
	11th to 20th	Day	7% 6% 20% 25% 27% 14%	490
	21st to end	Day	6% 9% 23% 24% 30% 9%	490
October	1st to 10th	Day	10% 8% 19% 27% 25% 10%	490
	11th to 20th	Day	12% 9% 17% 27% 23% 12%	409
	21st to end	Day	17% 8% 22% 32% 13% 7%	330
November	1st to 10th	Day	20% 9% 23% 30% 14% 4	300
	11th to 20th	Day	22% 13% 19% 24% 13% 9%	249
	21st to end	Day	19% 8% 25% 25% 20% 5%	200
December	1st to 10th	Day	21% 7% 21% 23% 18% 12%	200
	11th to 20th	Day	26% 12% 22% 22% 17% 3	200
	21st to end	Day	28% 5% 26% 25% 12% 3	220
January	1st to 10th	Night	29% 8% 21% 28% 13% 2	800
	11th to 20th	Night	23% 6% 18% 33% 17% 4	800
	21st to end	Night	20% 4 18% 35% 21% 2	880
February	1st to 10th	Night	24% 7% 24% 32% 13% 2	800
	11th to 20th	Night	19% 8% 21% 34% 17% 1	784
	21st to end	Night	18% 10% 22% 33% 15% 1	660
March	1st to 10th	Night	17% 6% 25% 34% 16% 3	800
	11th to 20th	Night	16% 8% 23% 31% 20% 2	800
	21st to end	Night	16% 7% 29% 35% 12% 1	880
April	1st to 10th	Night	15% 7% 23% 36% 18% 2	800
	11th to 20th	Night	12% 8% 31% 33% 15% 2	760
	21st to end	Night	10% 7% 28% 33% 21% 1	600
May	1st to 10th	Night	9% 7% 25% 34% 24% 2	446
	11th to 20th	Night	10% 6% 18% 34% 28% 5%	394
	21st to end	Night	7% 5% 21% 36% 28% 3	433
June	1st to 10th	Night	10% 5% 22% 39% 22% 3	399
	11th to 20th	Night	14% 6% 27% 35% 17% 2	380
	21st to end	Night	7% 3 18% 41% 28% 3	380
July	1st to 10th	Night	4 2 16% 45% 31% 2	370
	11th to 20th	Night	3 3 16% 47% 30% 1	368
	21st to end	Night	1 2 13% 47% 34% 3	416
August	1st to 10th	Night	4 1 15% 38% 37% 5%	378
	11th to 20th	Night	3 2 12% 36% 39% 8%	476
	21st to end	Night	4 3 18% 38% 33% 5%	832
September	1st to 10th	Night	4 2 15% 44% 29% 6%	760
	11th to 20th	Night	6% 3 17% 34% 32% 8%	760
	21st to end	Night	9% 4 19% 33% 29% 5%	760
October	1st to 10th	Night	13% 3 18% 38% 26% 2	760
	11th to 20th	Night	13% 6% 18% 33% 26% 3	760
	21st to end	Night	16% 5% 23% 35% 16% 5%	836
November	1st to 10th	Night	21% 5% 20% 37% 15% 1	780
	11th to 20th	Night	20% 9% 21% 33% 15% 2	800
	21st to end	Night	21% 5% 18% 34% 19% 3	800
December	1st to 10th	Night	18% 6% 18% 37% 19% 3	950
	11th to 20th	Night	26% 6% 20% 34% 13% 1	984
	21st to end	Night	30% 7% 21% 30% 11% 1	880

Page generated at 2025-06-07 07:28:14. Version ac07

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