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 2026-10-14.

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% 6% 2 6% 4 4 4 3 5% 6% 51%	153070
	Night	10% 7% 3 7% 4 4 4 4 5% 6% 45%	147411
Transparency	Day	33% 5% 10% 23% 19% 8%	152797
	Night	39% 6% 11% 21% 17% 7%	147266
Seeing	Day	12% 8% 22% 27% 22% 10%	16719
	Night	15% 6% 20% 36% 21% 3	26079

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	17% 17% 8% 14% 6% 5% 5% 4 5% 5% 15%	4723
	11th to 20th	Day	11% 8% 5% 10% 5% 6% 5% 4 6% 6% 35%	4716
	21st to end	Day	14% 12% 4 10% 5% 5% 5% 3 5% 5% 33%	5186
February	1st to 10th	Day	15% 13% 5% 9% 5% 5% 5% 4 5% 6% 27%	1733
	11th to 20th	Day	14% 14% 4 10% 6% 5% 5% 4 5% 5% 28%	1961
	21st to end	Day	12% 13% 4 8% 6% 5% 4 4 4 6% 33%	1730
March	1st to 10th	Day	6% 8% 3 6% 6% 6% 7% 5% 8% 9% 36%	4618
	11th to 20th	Day	8% 8% 3 8% 4 5% 5% 4 6% 6% 43%	4772
	21st to end	Day	11% 10% 4 10% 6% 5% 6% 4 7% 9% 28%	6101
April	1st to 10th	Day	9% 9% 3 8% 6% 5% 7% 5% 7% 8% 34%	2520
	11th to 20th	Day	8% 7% 3 7% 6% 5% 5% 5% 6% 8% 42%	2524
	21st to end	Day	9% 6% 2 6% 5% 4 5% 4 6% 8% 45%	2730
May	1st to 10th	Day	5% 4 1 5% 3 3 4 3 6% 8% 58%	8071
	11th to 20th	Day	7% 6% 2 6% 5% 5% 5% 4 6% 8% 47%	8160
	21st to end	Day	6% 5% 2 6% 4 5% 5% 4 6% 8% 49%	8993
June	1st to 10th	Day	11% 6% 2 7% 4 4 4 3 5% 7% 45%	2940
	11th to 20th	Day	8% 5% 2 5% 4 3 4 3 6% 8% 52%	2940
	21st to end	Day	5% 3 2 4 3 3 3 3 5% 7% 62%	2940
July	1st to 10th	Day	2 2 1 2 2 2 3 2 3 5% 77%	8220
	11th to 20th	Day	3 2 1 3 2 2 2 2 3 4 77%	8220
	21st to end	Day	2 2 1 2 1 2 2 2 3 5% 78%	8916
August	1st to 10th	Day	2 2 1 2 1 2 2 1 3 4 80%	6441
	11th to 20th	Day	2 1 1 3 2 3 3 2 5% 7% 71%	6123
	21st to end	Day	2 3 1 3 2 3 3 3 5% 7% 67%	6078
September	1st to 10th	Day	3 2 1 3 2 3 3 3 4 6% 69%	2520
	11th to 20th	Day	5% 4 2 5% 4 4 4 4 7% 7% 55%	2422
	21st to end	Day	5% 4 2 6% 4 4 5% 4 5% 8% 54%	2310
October	1st to 10th	Day	5% 4 2 4 3 3 4 3 4 8% 61%	3528
	11th to 20th	Day	7% 5% 2 5% 5% 5% 5% 4 6% 8% 47%	3143
	21st to end	Day	11% 7% 3 6% 4 4 5% 4 6% 7% 44%	3200
November	1st to 10th	Day	16% 7% 3 8% 5% 5% 4 5% 6% 7% 35%	1854
	11th to 20th	Day	17% 12% 5% 9% 6% 5% 4 4 5% 6% 27%	1784
	21st to end	Day	13% 14% 5% 12% 7% 5% 5% 4 6% 5% 24%	1680
December	1st to 10th	Day	13% 10% 4 11% 6% 6% 7% 4 6% 7% 26%	2398
	11th to 20th	Day	19% 16% 6% 14% 7% 6% 5% 3 3 4 16%	2783
	21st to end	Day	19% 14% 6% 12% 5% 5% 5% 4 6% 6% 18%	4092
January	1st to 10th	Night	21% 15% 7% 11% 6% 5% 6% 4 5% 5% 14%	8172
	11th to 20th	Night	10% 7% 4 8% 5% 5% 5% 4 6% 6% 40%	8182
	21st to end	Night	12% 11% 4 9% 4 4 5% 4 5% 6% 36%	8994
February	1st to 10th	Night	15% 14% 4 9% 5% 5% 5% 4 5% 6% 28%	2886
	11th to 20th	Night	13% 11% 4 8% 5% 5% 4 4 5% 7% 34%	2545
	21st to end	Night	12% 12% 4 8% 6% 5% 4 4 5% 6% 34%	2076
March	1st to 10th	Night	7% 7% 3 7% 4 5% 5% 5% 7% 8% 42%	5496
	11th to 20th	Night	10% 10% 4 7% 4 4 4 3 5% 6% 44%	5442
	21st to end	Night	9% 9% 4 9% 7% 7% 7% 5% 9% 9% 26%	5116
April	1st to 10th	Night	10% 10% 3 7% 6% 5% 4 5% 6% 8% 37%	2100
	11th to 20th	Night	8% 8% 3 7% 5% 5% 3 4 6% 5% 45%	2046
	21st to end	Night	8% 6% 3 7% 5% 5% 5% 5% 6% 8% 43%	1890
May	1st to 10th	Night	5% 4 1 4 3 4 5% 4 6% 6% 56%	4850
	11th to 20th	Night	7% 6% 3 7% 5% 4 6% 4 6% 8% 43%	4700
	21st to end	Night	6% 5% 2 6% 4 5% 5% 4 7% 8% 49%	5178
June	1st to 10th	Night	9% 6% 3 5% 5% 4 4 3 5% 7% 49%	1680
	11th to 20th	Night	9% 5% 2 4 5% 4 5% 4 6% 6% 52%	1680
	21st to end	Night	6% 5% 2 5% 4 4 4 4 6% 6% 55%	1680
July	1st to 10th	Night	2 2 2 1 2 2 2 4 6% 77%	4740
	11th to 20th	Night	1 1 1 2 2 3 3 2 4 5% 76%	4740
	21st to end	Night	3 3 1 2 1 1 2 2 3 5% 77%	5152
August	1st to 10th	Night	3 2 1 2 1 2 2 2 3 5% 79%	3709
	11th to 20th	Night	2 2 1 3 3 3 4 4 5% 7% 67%	3931
	21st to end	Night	2 3 1 3 2 3 3 2 4 6% 70%	5088
September	1st to 10th	Night	4 3 1 2 3 3 4 3 4 7% 67%	2100
	11th to 20th	Night	5% 4 1 5% 4 4 4 4 5% 7% 57%	2197
	21st to end	Night	7% 4 2 5% 3 3 4 4 5% 9% 55%	2310
October	1st to 10th	Night	5% 3 1 4 3 3 3 3 4 6% 63%	3889
	11th to 20th	Night	9% 4 2 5% 4 4 4 4 6% 7% 51%	4077
	21st to end	Night	11% 5% 2 6% 4 4 4 4 5% 7% 47%	4600
November	1st to 10th	Night	16% 9% 3 8% 5% 4 5% 4 6% 7% 34%	2665
	11th to 20th	Night	17% 9% 4 9% 5% 5% 5% 4 5% 6% 32%	2835
	21st to end	Night	15% 10% 4 8% 6% 5% 5% 5% 6% 5% 30%	2940
December	1st to 10th	Night	9% 8% 4 8% 6% 6% 6% 5% 7% 7% 34%	4962
	11th to 20th	Night	20% 16% 6% 13% 7% 5% 4 4 5% 6% 13%	5657
	21st to end	Night	19% 14% 5% 12% 6% 5% 4 3 5% 5% 21%	7106

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	70% 8% 10% 10% 2	4723
	11th to 20th	Day	46% 8% 17% 20% 7%	4740
	21st to end	Day	54% 5% 16% 17% 8%	5187
February	1st to 10th	Day	57% 8% 15% 13% 6% 1	1733
	11th to 20th	Day	57% 8% 12% 16% 6%	1970
	21st to end	Day	52% 8% 11% 20% 8% 1	1730
March	1st to 10th	Day	41% 6% 11% 25% 16% 1	4618
	11th to 20th	Day	40% 5% 12% 31% 12%	4772
	21st to end	Day	51% 9% 15% 18% 7%	6101
April	1st to 10th	Day	45% 8% 16% 21% 9% 1	2520
	11th to 20th	Day	40% 6% 14% 23% 14% 3	2524
	21st to end	Day	37% 7% 13% 25% 17% 2	2730
May	1st to 10th	Day	25% 4 7% 31% 30% 4	8071
	11th to 20th	Day	33% 6% 11% 31% 18% 2	8163
	21st to end	Day	32% 5% 15% 30% 16% 2	8994
June	1st to 10th	Day	39% 6% 9% 22% 21% 4	2940
	11th to 20th	Day	29% 5% 13% 26% 21% 6%	2940
	21st to end	Day	23% 5% 9% 29% 27% 7%	2940
July	1st to 10th	Day	12% 2 3 22% 31% 30%	8151
	11th to 20th	Day	14% 2 3 14% 31% 36%	8145
	21st to end	Day	11% 2 4 23% 36% 24%	8723
August	1st to 10th	Day	11% 2 3 12% 38% 34%	6424
	11th to 20th	Day	14% 3 6% 38% 32% 7%	6165
	21st to end	Day	17% 3 8% 31% 33% 7%	6077
September	1st to 10th	Day	16% 4 9% 30% 27% 14%	2520
	11th to 20th	Day	27% 5% 13% 25% 23% 8%	2422
	21st to end	Day	29% 5% 16% 29% 17% 4	2310
October	1st to 10th	Day	24% 3 10% 35% 24% 3	3528
	11th to 20th	Day	34% 5% 17% 28% 14% 1	3143
	21st to end	Day	39% 7% 12% 29% 12% 2	3200
November	1st to 10th	Day	47% 8% 16% 22% 6% 1	1854
	11th to 20th	Day	57% 7% 15% 16% 3 1	1784
	21st to end	Day	58% 11% 14% 11% 4 1	1680
December	1st to 10th	Day	54% 8% 20% 14% 3	2398
	11th to 20th	Day	72% 8% 9% 10% 1	2785
	21st to end	Day	65% 8% 15% 10% 2	4092
January	1st to 10th	Night	69% 8% 12% 10% 1	8172
	11th to 20th	Night	43% 6% 19% 22% 9%	8220
	21st to end	Night	49% 7% 15% 22% 8%	8994
February	1st to 10th	Night	56% 7% 15% 16% 6% 1	2886
	11th to 20th	Night	50% 7% 16% 18% 8% 1	2547
	21st to end	Night	50% 7% 14% 19% 8% 1	2076
March	1st to 10th	Night	37% 6% 9% 27% 20% 1	5496
	11th to 20th	Night	42% 5% 8% 30% 15%	5443
	21st to end	Night	49% 9% 12% 23% 6% 1	5116
April	1st to 10th	Night	43% 7% 12% 24% 12% 1	2100
	11th to 20th	Night	39% 7% 9% 25% 16% 4	2046
	21st to end	Night	37% 7% 12% 20% 19% 4	1890
May	1st to 10th	Night	26% 5% 6% 28% 31% 5%	4847
	11th to 20th	Night	36% 7% 8% 25% 22% 2	4700
	21st to end	Night	31% 7% 14% 29% 18% 1	5182
June	1st to 10th	Night	34% 5% 8% 24% 23% 5%	1680
	11th to 20th	Night	32% 5% 6% 26% 25% 6%	1680
	21st to end	Night	28% 4 8% 23% 26% 11%	1680
July	1st to 10th	Night	10% 2 3 18% 32% 34%	4700
	11th to 20th	Night	12% 3 3 10% 29% 43%	4692
	21st to end	Night	12% 2 3 15% 39% 30%	5040
August	1st to 10th	Night	11% 2 3 8% 34% 42%	3701
	11th to 20th	Night	17% 4 5% 28% 35% 11%	3955
	21st to end	Night	17% 3 5% 27% 35% 14%	5088
September	1st to 10th	Night	18% 4 7% 24% 29% 19%	2100
	11th to 20th	Night	26% 5% 9% 24% 24% 11%	2197
	21st to end	Night	26% 5% 10% 30% 21% 8%	2310
October	1st to 10th	Night	22% 4 9% 31% 32% 2	3889
	11th to 20th	Night	32% 5% 14% 23% 24% 2	4077
	21st to end	Night	37% 5% 9% 33% 15% 2	4600
November	1st to 10th	Night	49% 7% 14% 22% 6% 1	2665
	11th to 20th	Night	53% 7% 16% 17% 6% 1	2835
	21st to end	Night	52% 9% 17% 16% 5%	2940
December	1st to 10th	Night	44% 11% 20% 20% 4	4962
	11th to 20th	Night	71% 8% 12% 8% 2	5654
	21st to end	Night	64% 7% 12% 13% 4	7106

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% 30% 20% 11% 5%	220
	11th to 20th	Day	25% 5% 17% 26% 22% 5%	220
	21st to end	Day	25% 5% 20% 29% 17% 5%	242
February	1st to 10th	Day	22% 7% 28% 26% 13% 4	273
	11th to 20th	Day	23% 11% 23% 24% 16% 3	487
	21st to end	Day	19% 12% 27% 25% 14% 2	446
March	1st to 10th	Day	17% 12% 31% 20% 17% 4	540
	11th to 20th	Day	15% 12% 23% 24% 19% 7%	540
	21st to end	Day	16% 13% 28% 26% 14% 3	594
April	1st to 10th	Day	14% 13% 24% 25% 16% 7%	540
	11th to 20th	Day	11% 14% 32% 23% 16% 5%	532
	21st to end	Day	10% 9% 27% 26% 20% 7%	540
May	1st to 10th	Day	7% 10% 21% 33% 22% 6%	543
	11th to 20th	Day	16% 6% 23% 25% 16% 13%	568
	21st to end	Day	9% 6% 22% 27% 22% 15%	617
June	1st to 10th	Day	12% 8% 21% 23% 24% 13%	570
	11th to 20th	Day	9% 10% 30% 30% 14% 8%	570
	21st to end	Day	5% 5% 22% 28% 28% 12%	570
July	1st to 10th	Day	3 2 19% 32% 37% 7%	566
	11th to 20th	Day	2 3 20% 36% 29% 10%	564
	21st to end	Day	2 3 16% 31% 31% 17%	619
August	1st to 10th	Day	3 4 16% 30% 31% 16%	567
	11th to 20th	Day	3 2 14% 30% 34% 18%	557
	21st to end	Day	5% 6% 19% 25% 27% 18%	627
September	1st to 10th	Day	5% 3 19% 27% 27% 19%	570
	11th to 20th	Day	7% 6% 20% 25% 27% 15%	570
	21st to end	Day	6% 9% 22% 24% 30% 9%	570
October	1st to 10th	Day	9% 8% 19% 27% 26% 12%	570
	11th to 20th	Day	13% 10% 17% 27% 21% 12%	458
	21st to end	Day	16% 8% 24% 32% 14% 6%	363
November	1st to 10th	Day	20% 11% 22% 29% 14% 3	330
	11th to 20th	Day	22% 13% 19% 26% 13% 8%	274
	21st to end	Day	18% 8% 26% 25% 19% 4	220
December	1st to 10th	Day	25% 6% 20% 21% 17% 10%	220
	11th to 20th	Day	27% 14% 21% 21% 15% 2	220
	21st to end	Day	27% 6% 26% 25% 13% 3	242
January	1st to 10th	Night	29% 8% 21% 28% 12% 2	840
	11th to 20th	Night	22% 6% 17% 34% 17% 4	840
	21st to end	Night	20% 4 17% 36% 21% 2	924
February	1st to 10th	Night	23% 7% 23% 33% 13% 2	840
	11th to 20th	Night	19% 8% 21% 34% 17% 1	824
	21st to end	Night	18% 10% 23% 33% 15% 1	692
March	1st to 10th	Night	17% 6% 25% 34% 16% 2	840
	11th to 20th	Night	17% 9% 23% 30% 19% 2	840
	21st to end	Night	16% 8% 28% 35% 12% 1	924
April	1st to 10th	Night	14% 6% 23% 37% 18% 2	840
	11th to 20th	Night	12% 8% 30% 33% 15% 2	798
	21st to end	Night	10% 7% 27% 33% 21% 1	630
May	1st to 10th	Night	8% 7% 25% 35% 24% 2	468
	11th to 20th	Night	10% 6% 19% 34% 27% 5%	414
	21st to end	Night	7% 5% 21% 36% 27% 3	455
June	1st to 10th	Night	11% 5% 22% 39% 21% 2	420
	11th to 20th	Night	12% 6% 28% 37% 16% 1	420
	21st to end	Night	7% 4 18% 42% 27% 2	420
July	1st to 10th	Night	4 2 16% 46% 31% 2	410
	11th to 20th	Night	3 4 16% 47% 29% 1	408
	21st to end	Night	2 2 13% 46% 35% 2	460
August	1st to 10th	Night	4 2 14% 39% 36% 5%	418
	11th to 20th	Night	3 2 12% 39% 38% 7%	527
	21st to end	Night	4 2 18% 39% 33% 5%	920
September	1st to 10th	Night	5% 2 15% 44% 29% 5%	840
	11th to 20th	Night	7% 3 17% 35% 32% 7%	840
	21st to end	Night	8% 5% 20% 33% 29% 5%	840
October	1st to 10th	Night	12% 3 17% 40% 26% 2	840
	11th to 20th	Night	13% 7% 19% 33% 25% 3	812
	21st to end	Night	15% 5% 24% 36% 16% 4	880
November	1st to 10th	Night	21% 6% 20% 37% 14% 1	820
	11th to 20th	Night	21% 9% 21% 33% 15% 2	840
	21st to end	Night	22% 5% 18% 35% 19% 3	840
December	1st to 10th	Night	19% 6% 18% 36% 18% 3	998
	11th to 20th	Night	26% 7% 20% 33% 12% 1	1033
	21st to end	Night	29% 7% 21% 30% 11% 1	924

Page generated at 2026-10-11 02:06:30. Version ac07

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