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 2024-11-02.

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% 49%	101165
	Night	11% 8% 3 7% 5% 4 4 4 5% 6% 43%	97881
Transparency	Day	35% 6% 11% 22% 17% 9%	100933
	Night	41% 7% 11% 20% 14% 8%	97759
Seeing	Day	12% 8% 22% 27% 22% 10%	14269
	Night	15% 5% 21% 35% 21% 3	23662

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% 16% 6% 11% 7% 6% 6% 5% 5% 5% 17%	2539
	11th to 20th	Day	20% 13% 6% 11% 6% 6% 4 4 6% 5% 18%	2516
	21st to end	Day	22% 18% 5% 12% 5% 5% 4 3 4 4 17%	2794
February	1st to 10th	Day	16% 13% 5% 8% 5% 5% 5% 5% 5% 6% 27%	1567
	11th to 20th	Day	14% 14% 4 10% 6% 5% 5% 4 5% 5% 29%	1769
	21st to end	Day	11% 14% 4 8% 6% 5% 4 4 4 6% 32%	1570
March	1st to 10th	Day	9% 10% 3 6% 6% 4 7% 4 8% 9% 35%	3138
	11th to 20th	Day	7% 6% 2 6% 4 5% 5% 4 5% 6% 51%	3251
	21st to end	Day	11% 10% 4 9% 7% 5% 6% 5% 7% 8% 28%	4165
April	1st to 10th	Day	9% 9% 3 8% 6% 5% 7% 5% 7% 8% 32%	2280
	11th to 20th	Day	8% 7% 3 7% 6% 5% 5% 5% 6% 7% 42%	2280
	21st to end	Day	9% 7% 2 7% 5% 4 5% 4 6% 8% 43%	2470
May	1st to 10th	Day	9% 6% 2 5% 3 3 4 3 6% 8% 51%	4348
	11th to 20th	Day	5% 4 1 5% 4 4 4 4 6% 7% 57%	4377
	21st to end	Day	7% 6% 3 7% 6% 5% 6% 5% 6% 7% 42%	4813
June	1st to 10th	Day	11% 7% 3 7% 4 4 4 3 5% 7% 44%	2660
	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	8% 5% 2 5% 4 3 4 4 4 7% 53%	1990
	11th to 20th	Day	10% 5% 1 5% 4 4 4 4 6% 8% 49%	1819
	21st to end	Day	12% 7% 3 7% 5% 4 4 4 6% 6% 43%	1881
November	1st to 10th	Day	16% 8% 2 7% 5% 5% 5% 5% 6% 8% 34%	1683
	11th to 20th	Day	17% 13% 5% 8% 6% 5% 4 4 5% 6% 28%	1615
	21st to end	Day	13% 14% 4 11% 7% 5% 5% 4 6% 5% 25%	1520
December	1st to 10th	Day	15% 15% 4 10% 6% 6% 7% 4 5% 6% 21%	1353
	11th to 20th	Day	18% 15% 7% 17% 8% 5% 5% 4 4 4 14%	1723
	21st to end	Day	15% 15% 6% 13% 6% 5% 5% 4 6% 6% 19%	2794
January	1st to 10th	Night	21% 16% 6% 10% 6% 5% 6% 3 5% 5% 18%	4406
	11th to 20th	Night	19% 12% 5% 10% 5% 5% 4 3 5% 7% 24%	4382
	21st to end	Night	20% 14% 5% 11% 5% 4 5% 4 5% 6% 21%	4862
February	1st to 10th	Night	16% 15% 4 8% 5% 5% 4 4 5% 6% 29%	2612
	11th to 20th	Night	13% 11% 3 8% 5% 5% 4 5% 5% 7% 34%	2297
	21st to end	Night	11% 11% 5% 8% 6% 5% 5% 4 5% 6% 33%	1884
March	1st to 10th	Night	8% 8% 2 7% 5% 5% 6% 5% 7% 8% 40%	3736
	11th to 20th	Night	8% 7% 2 5% 4 3 3 3 5% 6% 54%	3723
	21st to end	Night	10% 7% 3 9% 7% 8% 7% 6% 9% 8% 26%	3488
April	1st to 10th	Night	11% 10% 3 7% 6% 5% 4 5% 6% 8% 35%	1900
	11th to 20th	Night	8% 8% 3 8% 5% 5% 3 5% 6% 5% 44%	1850
	21st to end	Night	9% 6% 3 7% 5% 5% 5% 4 6% 8% 42%	1710
May	1st to 10th	Night	8% 6% 2 6% 5% 5% 5% 4 6% 7% 47%	2610
	11th to 20th	Night	6% 5% 2 5% 4 3 4 4 6% 7% 53%	2516
	21st to end	Night	9% 4 2 5% 4 5% 5% 4 7% 8% 47%	2762
June	1st to 10th	Night	9% 7% 3 5% 5% 4 4 3 5% 7% 48%	1520
	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	9% 5% 2 5% 4 3 3 4 5% 6% 54%	2187
	11th to 20th	Night	10% 6% 2 5% 4 4 4 3 5% 7% 49%	2361
	21st to end	Night	12% 7% 3 6% 4 4 4 4 5% 7% 45%	2717
November	1st to 10th	Night	16% 9% 3 8% 5% 4 4 4 6% 6% 34%	2430
	11th to 20th	Night	16% 9% 3 9% 5% 5% 5% 4 5% 6% 33%	2565
	21st to end	Night	15% 9% 4 8% 6% 5% 5% 5% 6% 5% 33%	2660
December	1st to 10th	Night	14% 12% 4 9% 6% 5% 5% 4 5% 6% 29%	2802
	11th to 20th	Night	18% 15% 7% 14% 8% 5% 4 4 6% 5% 14%	3482
	21st to end	Night	17% 12% 5% 13% 7% 6% 4 3 5% 6% 22%	4862

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	65% 10% 13% 10% 1	2539
	11th to 20th	Day	65% 10% 12% 11% 3 1	2540
	21st to end	Day	71% 6% 13% 8% 1	2794
February	1st to 10th	Day	57% 9% 16% 12% 5%	1567
	11th to 20th	Day	55% 8% 13% 17% 6%	1778
	21st to end	Day	53% 8% 11% 19% 8% 1	1570
March	1st to 10th	Day	42% 7% 11% 26% 12%	3138
	11th to 20th	Day	33% 6% 14% 37% 10%	3251
	21st to end	Day	50% 11% 16% 15% 8% 1	4165
April	1st to 10th	Day	47% 8% 16% 20% 9% 1	2280
	11th to 20th	Day	40% 6% 15% 22% 14% 3	2280
	21st to end	Day	38% 7% 13% 25% 15% 2	2470
May	1st to 10th	Day	30% 5% 10% 31% 20% 3	4348
	11th to 20th	Day	25% 6% 11% 33% 22% 4	4380
	21st to end	Day	38% 8% 16% 28% 10% 2	4814
June	1st to 10th	Day	40% 6% 9% 23% 20% 3	2660
	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	32% 5% 13% 30% 18% 2	1990
	11th to 20th	Day	34% 6% 16% 32% 11% 1	1819
	21st to end	Day	41% 8% 15% 25% 10% 1	1881
November	1st to 10th	Day	47% 9% 16% 21% 6% 1	1683
	11th to 20th	Day	57% 8% 15% 16% 3 1	1615
	21st to end	Day	56% 12% 15% 12% 4 1	1520
December	1st to 10th	Day	62% 9% 13% 12% 4	1353
	11th to 20th	Day	73% 10% 7% 8% 1	1725
	21st to end	Day	63% 8% 14% 11% 3	2794
January	1st to 10th	Night	67% 7% 12% 12% 1 1	4406
	11th to 20th	Night	59% 7% 17% 12% 3	4420
	21st to end	Night	63% 9% 15% 11% 2	4862
February	1st to 10th	Night	56% 7% 15% 15% 6% 1	2612
	11th to 20th	Night	49% 8% 17% 18% 8%	2299
	21st to end	Night	50% 8% 14% 19% 8% 1	1884
March	1st to 10th	Night	39% 7% 10% 28% 14% 1	3736
	11th to 20th	Night	32% 6% 10% 36% 17%	3724
	21st to end	Night	49% 11% 15% 20% 5% 1	3488
April	1st to 10th	Night	44% 7% 12% 23% 12% 1	1900
	11th to 20th	Night	40% 7% 9% 24% 16% 4	1850
	21st to end	Night	39% 7% 13% 19% 17% 5%	1710
May	1st to 10th	Night	33% 7% 8% 26% 20% 4	2610
	11th to 20th	Night	27% 7% 7% 28% 27% 4	2516
	21st to end	Night	32% 9% 16% 31% 11% 1	2762
June	1st to 10th	Night	36% 5% 8% 23% 22% 5%	1520
	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	30% 5% 10% 28% 26% 1	2187
	11th to 20th	Night	35% 6% 12% 25% 20% 3	2361
	21st to end	Night	39% 6% 12% 26% 14% 2	2717
November	1st to 10th	Night	50% 7% 13% 23% 6% 1	2430
	11th to 20th	Night	53% 7% 16% 17% 6% 1	2565
	21st to end	Night	50% 9% 17% 18% 6%	2660
December	1st to 10th	Night	55% 10% 15% 17% 4	2802
	11th to 20th	Night	68% 11% 11% 7% 2	3479
	21st to end	Night	63% 7% 12% 13% 5%	4862

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% 19% 12% 6%	180
	11th to 20th	Day	30% 6% 17% 27% 16% 4	180
	21st to end	Day	29% 6% 23% 25% 15% 3	198
February	1st to 10th	Day	23% 7% 30% 25% 12% 3	227
	11th to 20th	Day	24% 12% 24% 23% 14% 3	415
	21st to end	Day	19% 11% 27% 26% 15% 3	382
March	1st to 10th	Day	18% 12% 30% 19% 17% 4	460
	11th to 20th	Day	12% 10% 23% 26% 22% 8%	460
	21st to end	Day	15% 13% 28% 26% 14% 3	506
April	1st to 10th	Day	15% 13% 25% 25% 15% 5%	460
	11th to 20th	Day	12% 14% 33% 22% 15% 5%	452
	21st to end	Day	11% 10% 28% 26% 19% 6%	460
May	1st to 10th	Day	8% 10% 22% 32% 22% 6%	463
	11th to 20th	Day	16% 5% 22% 25% 17% 15%	488
	21st to end	Day	9% 6% 23% 26% 23% 13%	529
June	1st to 10th	Day	12% 6% 21% 23% 24% 13%	490
	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	21% 10% 22% 31% 13% 3	273
	11th to 20th	Day	22% 12% 18% 25% 14% 9%	225
	21st to end	Day	18% 7% 24% 26% 21% 5%	180
December	1st to 10th	Day	22% 7% 22% 24% 16% 9%	180
	11th to 20th	Day	26% 11% 23% 22% 16% 3	180
	21st to end	Day	27% 5% 26% 26% 13% 3	198
January	1st to 10th	Night	29% 8% 22% 26% 13% 2	760
	11th to 20th	Night	24% 6% 18% 31% 17% 4	760
	21st to end	Night	21% 4 18% 34% 21% 2	836
February	1st to 10th	Night	24% 6% 23% 32% 13% 1	760
	11th to 20th	Night	19% 8% 22% 33% 17% 1	744
	21st to end	Night	17% 10% 22% 34% 16% 1	628
March	1st to 10th	Night	17% 6% 25% 33% 16% 3	760
	11th to 20th	Night	16% 8% 22% 31% 21% 2	760
	21st to end	Night	16% 6% 29% 35% 13% 2	836
April	1st to 10th	Night	15% 7% 24% 36% 17% 2	760
	11th to 20th	Night	12% 8% 31% 33% 15% 2	722
	21st to end	Night	11% 6% 28% 33% 20% 1	570
May	1st to 10th	Night	9% 7% 25% 34% 24% 2	424
	11th to 20th	Night	10% 5% 16% 34% 29% 5%	374
	21st to end	Night	7% 5% 21% 37% 27% 3	411
June	1st to 10th	Night	11% 4 22% 39% 21% 2	380
	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	22% 5% 21% 36% 15% 1	748
	11th to 20th	Night	20% 8% 21% 33% 15% 2	760
	21st to end	Night	21% 5% 19% 34% 19% 3	760
December	1st to 10th	Night	18% 6% 19% 37% 17% 3	902
	11th to 20th	Night	25% 6% 20% 34% 13% 1	935
	21st to end	Night	30% 7% 20% 31% 11% 1	836

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