Rimrock Meadows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rimrock Meadows clear sky chart from 2005-11-06 to 2025-04-11.

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	6% 7% 3 7% 4 4 4 4 5% 7% 48%	117359
	Night	7% 9% 3 8% 4 4 4 4 5% 7% 45%	119641
Transparency	Day	35% 5% 11% 22% 18% 8%	117128
	Night	39% 5% 11% 23% 16% 6%	119518
Seeing	Day	9% 8% 22% 29% 23% 9%	14760
	Night	11% 5% 23% 36% 21% 3	23935

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	13% 18% 7% 15% 7% 5% 4 3 3 4 21%	3639
	11th to 20th	Day	10% 11% 4 9% 5% 4 3 4 5% 8% 36%	3616
	21st to end	Day	15% 16% 6% 12% 4 3 4 3 4 4 29%	4004
February	1st to 10th	Day	10% 14% 4 11% 7% 5% 5% 5% 5% 6% 27%	1725
	11th to 20th	Day	9% 14% 5% 9% 6% 5% 3 4 6% 7% 34%	1773
	21st to end	Day	7% 11% 3 9% 5% 6% 5% 4 7% 8% 34%	1650
March	1st to 10th	Day	4 8% 3 7% 5% 7% 7% 5% 7% 9% 39%	4518
	11th to 20th	Day	4 8% 3 7% 5% 5% 4 4 5% 7% 48%	4797
	21st to end	Day	7% 7% 3 9% 6% 7% 7% 6% 8% 10% 31%	5894
April	1st to 10th	Day	8% 8% 3 7% 6% 5% 6% 5% 7% 9% 37%	2400
	11th to 20th	Day	6% 7% 3 7% 5% 5% 6% 4 7% 8% 43%	2254
	21st to end	Day	4 6% 2 8% 6% 5% 5% 4 7% 9% 43%	2501
May	1st to 10th	Day	6% 7% 2 4 3 4 4 3 5% 8% 56%	4420
	11th to 20th	Day	4 4 1 4 3 3 4 4 6% 7% 58%	4377
	21st to end	Day	7% 8% 3 8% 6% 6% 5% 4 6% 7% 40%	4813
June	1st to 10th	Day	8% 7% 2 6% 5% 5% 5% 4 6% 7% 45%	2660
	11th to 20th	Day	7% 4 2 6% 5% 5% 5% 4 7% 7% 49%	2660
	21st to end	Day	4 4 2 5% 3 3 3 3 5% 7% 61%	2660
July	1st to 10th	Day	1 1 2 2 2 2 2 3 4 81%	4420
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 3 80%	4420
	21st to end	Day	1 1 1 2 1 2 2 2 3 4 80%	4790
August	1st to 10th	Day	2 2 1 3 2 2 3 2 5% 5% 73%	4401
	11th to 20th	Day	1 2 1 3 2 3 3 3 5% 7% 71%	4155
	21st to end	Day	4 4 1 5% 3 4 3 3 4 5% 64%	4180
September	1st to 10th	Day	3 2 1 3 2 2 3 2 5% 7% 70%	2280
	11th to 20th	Day	4 5% 2 5% 4 5% 5% 4 5% 7% 55%	2261
	21st to end	Day	6% 4 2 5% 3 4 3 3 5% 7% 56%	2077
October	1st to 10th	Day	4 4 2 3 3 3 3 3 6% 8% 62%	3180
	11th to 20th	Day	5% 4 3 7% 5% 5% 6% 5% 6% 8% 46%	3135
	21st to end	Day	8% 6% 1 6% 5% 5% 5% 4 6% 6% 48%	3101
November	1st to 10th	Day	12% 10% 4 10% 5% 6% 5% 4 5% 6% 34%	1749
	11th to 20th	Day	10% 15% 4 9% 5% 5% 5% 4 6% 6% 31%	1600
	21st to end	Day	11% 13% 5% 12% 5% 6% 4 4 5% 7% 27%	1600
December	1st to 10th	Day	9% 10% 3 14% 7% 5% 5% 5% 5% 8% 30%	2620
	11th to 20th	Day	13% 19% 7% 17% 7% 5% 4 3 4 5% 16%	3025
	21st to end	Day	11% 20% 7% 15% 7% 7% 5% 4 4 5% 15%	4004
January	1st to 10th	Night	13% 20% 8% 14% 6% 5% 4 3 4 5% 19%	6306
	11th to 20th	Night	9% 11% 4 9% 4 4 3 3 5% 7% 40%	6282
	21st to end	Night	12% 16% 7% 13% 5% 4 3 3 4 5% 30%	6952
February	1st to 10th	Night	8% 15% 4 9% 5% 5% 6% 5% 6% 6% 30%	2672
	11th to 20th	Night	10% 11% 2 8% 5% 5% 5% 4 7% 8% 36%	2513
	21st to end	Night	8% 12% 3 8% 6% 6% 5% 4 6% 8% 34%	1980
March	1st to 10th	Night	5% 8% 3 6% 5% 5% 5% 5% 8% 9% 41%	5376
	11th to 20th	Night	5% 9% 3 7% 4 4 4 4 5% 7% 47%	5185
	21st to end	Night	6% 7% 3 9% 6% 8% 6% 5% 8% 9% 33%	5080
April	1st to 10th	Night	8% 9% 3 8% 6% 4 5% 4 6% 8% 41%	2000
	11th to 20th	Night	6% 8% 3 6% 6% 4 4 4 5% 6% 48%	1883
	21st to end	Night	6% 6% 2 7% 4 4 4 5% 6% 10% 46%	1675
May	1st to 10th	Night	5% 6% 2 5% 3 3 4 3 5% 6% 58%	2540
	11th to 20th	Night	5% 3 1 3 3 3 4 4 5% 7% 61%	2516
	21st to end	Night	5% 4 2 5% 4 4 4 4 7% 10% 53%	2762
June	1st to 10th	Night	7% 5% 2 6% 5% 3 5% 3 6% 9% 49%	1520
	11th to 20th	Night	5% 4 1 5% 4 3 4 4 6% 7% 56%	1520
	21st to end	Night	3 3 1 5% 4 3 4 3 5% 7% 63%	1520
July	1st to 10th	Night	1 1 1 1 2 1 1 2 3 4 82%	2540
	11th to 20th	Night	1 1 1 1 1 1 2 3 3 85%	2540
	21st to end	Night	1 1 2 1 2 2 2 3 4 82%	2762
August	1st to 10th	Night	2 3 1 3 2 2 2 2 4 6% 74%	2529
	11th to 20th	Night	2 2 1 4 2 3 3 3 5% 6% 69%	2673
	21st to end	Night	2 3 2 4 3 3 3 3 4 6% 67%	3498
September	1st to 10th	Night	2 2 1 3 2 3 3 3 5% 6% 69%	1900
	11th to 20th	Night	3 4 2 6% 4 3 5% 3 5% 7% 59%	1919
	21st to end	Night	5% 3 2 4 3 5% 3 4 6% 8% 57%	2099
October	1st to 10th	Night	5% 4 1 4 2 3 4 4 6% 9% 60%	3800
	11th to 20th	Night	6% 4 2 5% 4 5% 5% 5% 6% 8% 49%	3801
	21st to end	Night	9% 6% 2 8% 5% 4 4 4 5% 7% 45%	4457
November	1st to 10th	Night	12% 10% 4 7% 5% 4 5% 4 6% 8% 35%	2549
	11th to 20th	Night	10% 11% 4 7% 5% 5% 5% 4 7% 7% 34%	2800
	21st to end	Night	11% 13% 4 11% 5% 5% 5% 4 5% 6% 30%	2800
December	1st to 10th	Night	7% 9% 3 9% 5% 5% 4 4 5% 7% 43%	4560
	11th to 20th	Night	14% 15% 6% 16% 8% 6% 6% 4 6% 6% 13%	5180
	21st to end	Night	15% 20% 5% 11% 5% 5% 4 3 5% 5% 22%	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	69% 5% 6% 13% 6% 1	3639
	11th to 20th	Day	47% 5% 17% 24% 7%	3640
	21st to end	Day	60% 5% 9% 20% 7%	4004
February	1st to 10th	Day	55% 9% 15% 14% 5% 2	1725
	11th to 20th	Day	48% 8% 17% 18% 10% 1	1782
	21st to end	Day	45% 9% 16% 20% 9% 1	1650
March	1st to 10th	Day	38% 6% 12% 23% 20% 1	4518
	11th to 20th	Day	35% 5% 9% 34% 17% 1	4797
	21st to end	Day	44% 9% 17% 20% 10% 1	5894
April	1st to 10th	Day	41% 8% 15% 23% 12% 2	2400
	11th to 20th	Day	35% 6% 15% 21% 16% 5%	2254
	21st to end	Day	34% 7% 13% 24% 18% 4	2501
May	1st to 10th	Day	25% 5% 9% 23% 29% 9%	4420
	11th to 20th	Day	21% 6% 11% 33% 24% 6%	4380
	21st to end	Day	37% 9% 14% 26% 12% 1	4814
June	1st to 10th	Day	36% 6% 10% 23% 19% 6%	2660
	11th to 20th	Day	30% 5% 12% 28% 19% 6%	2660
	21st to end	Day	22% 3 10% 29% 26% 10%	2660
July	1st to 10th	Day	10% 2 5% 13% 30% 40%	4351
	11th to 20th	Day	12% 2 3 10% 23% 49%	4345
	21st to end	Day	10% 1 3 19% 36% 30%	4639
August	1st to 10th	Day	15% 2 5% 17% 36% 25%	4384
	11th to 20th	Day	15% 2 7% 38% 30% 8%	4197
	21st to end	Day	24% 3 9% 27% 31% 8%	4179
September	1st to 10th	Day	16% 4 8% 29% 31% 13%	2280
	11th to 20th	Day	27% 6% 12% 23% 25% 8%	2261
	21st to end	Day	27% 5% 17% 28% 18% 6%	2077
October	1st to 10th	Day	22% 3 12% 38% 23% 2	3180
	11th to 20th	Day	36% 5% 16% 25% 17% 1	3135
	21st to end	Day	36% 5% 13% 28% 13% 5%	3101
November	1st to 10th	Day	49% 7% 15% 17% 10% 1	1749
	11th to 20th	Day	53% 7% 16% 17% 7% 1	1600
	21st to end	Day	55% 9% 16% 12% 7% 2	1600
December	1st to 10th	Day	54% 6% 15% 20% 5%	2620
	11th to 20th	Day	72% 6% 7% 10% 5%	3028
	21st to end	Day	72% 6% 7% 11% 4	4004
January	1st to 10th	Night	68% 5% 9% 13% 4	6306
	11th to 20th	Night	44% 5% 17% 24% 9%	6320
	21st to end	Night	57% 6% 10% 19% 7% 1	6952
February	1st to 10th	Night	51% 9% 17% 15% 7% 1	2672
	11th to 20th	Night	44% 9% 19% 18% 10% 2	2515
	21st to end	Night	46% 9% 14% 19% 11% 1	1980
March	1st to 10th	Night	35% 5% 12% 27% 18% 3	5376
	11th to 20th	Night	35% 4 9% 33% 18% 1	5186
	21st to end	Night	42% 9% 18% 24% 7% 1	5080
April	1st to 10th	Night	41% 6% 15% 25% 12% 2	2000
	11th to 20th	Night	34% 6% 13% 24% 19% 4	1883
	21st to end	Night	32% 8% 12% 26% 19% 3	1675
May	1st to 10th	Night	26% 4 7% 20% 34% 8%	2540
	11th to 20th	Night	19% 5% 8% 32% 31% 4	2516
	21st to end	Night	23% 8% 18% 38% 11% 2	2762
June	1st to 10th	Night	32% 6% 10% 25% 21% 6%	1520
	11th to 20th	Night	25% 5% 13% 31% 22% 4	1520
	21st to end	Night	21% 4 10% 28% 28% 9%	1520
July	1st to 10th	Night	8% 2 5% 14% 29% 41%	2500
	11th to 20th	Night	7% 1 3 11% 23% 54%	2492
	21st to end	Night	8% 1 3 17% 36% 35%	2674
August	1st to 10th	Night	15% 1 4 14% 39% 27%	2521
	11th to 20th	Night	18% 1 6% 37% 28% 10%	2697
	21st to end	Night	20% 2 7% 28% 31% 12%	3498
September	1st to 10th	Night	15% 3 9% 25% 29% 18%	1900
	11th to 20th	Night	23% 5% 10% 25% 26% 10%	1919
	21st to end	Night	23% 5% 13% 32% 19% 8%	2099
October	1st to 10th	Night	22% 3 8% 43% 23% 1	3800
	11th to 20th	Night	32% 4 14% 28% 20% 2	3801
	21st to end	Night	39% 4 11% 27% 16% 3	4457
November	1st to 10th	Night	45% 7% 17% 19% 9% 2	2549
	11th to 20th	Night	47% 9% 15% 19% 8% 2	2800
	21st to end	Night	54% 9% 14% 15% 7% 1	2800
December	1st to 10th	Night	42% 7% 18% 27% 6%	4560
	11th to 20th	Night	72% 7% 11% 7% 3	5176
	21st to end	Night	65% 6% 10% 12% 7% 1	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	23% 7% 24% 30% 15% 2	200
	11th to 20th	Day	22% 5% 19% 32% 17% 7%	200
	21st to end	Day	22% 1 17% 33% 20% 6%	220
February	1st to 10th	Day	14% 6% 30% 34% 14% 2	325
	11th to 20th	Day	16% 6% 25% 33% 18% 3	405
	21st to end	Day	11% 8% 29% 31% 19% 2	414
March	1st to 10th	Day	12% 7% 28% 32% 17% 4	500
	11th to 20th	Day	12% 10% 23% 27% 21% 7%	500
	21st to end	Day	13% 12% 27% 29% 17% 2	550
April	1st to 10th	Day	13% 13% 25% 25% 18% 6%	500
	11th to 20th	Day	8% 18% 31% 22% 15% 6%	453
	21st to end	Day	7% 12% 26% 29% 17% 8%	460
May	1st to 10th	Day	6% 11% 27% 32% 19% 5%	463
	11th to 20th	Day	11% 9% 22% 25% 22% 11%	488
	21st to end	Day	9% 7% 21% 24% 26% 12%	529
June	1st to 10th	Day	9% 10% 22% 28% 21% 10%	490
	11th to 20th	Day	8% 10% 26% 33% 17% 6%	490
	21st to end	Day	3 6% 21% 27% 30% 13%	490
July	1st to 10th	Day	2 5% 17% 34% 34% 9%	486
	11th to 20th	Day	2 4 20% 32% 29% 14%	484
	21st to end	Day	3 14% 33% 33% 16%	531
August	1st to 10th	Day	4 3 14% 30% 31% 19%	487
	11th to 20th	Day	2 3 13% 28% 31% 22%	477
	21st to end	Day	4 6% 20% 27% 27% 17%	539
September	1st to 10th	Day	5% 4 15% 30% 28% 18%	490
	11th to 20th	Day	6% 6% 20% 29% 27% 12%	490
	21st to end	Day	7% 10% 21% 28% 26% 7%	490
October	1st to 10th	Day	7% 9% 24% 30% 23% 7%	490
	11th to 20th	Day	9% 8% 19% 29% 27% 7%	476
	21st to end	Day	13% 8% 26% 32% 18% 3	330
November	1st to 10th	Day	16% 11% 20% 34% 17% 1	293
	11th to 20th	Day	18% 10% 28% 22% 18% 7%	200
	21st to end	Day	16% 4 16% 38% 22% 5%	200
December	1st to 10th	Day	17% 7% 16% 26% 24% 12%	200
	11th to 20th	Day	21% 7% 24% 34% 14% 2	200
	21st to end	Day	18% 7% 20% 36% 15% 4	220
January	1st to 10th	Night	24% 5% 24% 31% 15% 2	800
	11th to 20th	Night	19% 4 21% 33% 20% 3	800
	21st to end	Night	17% 3 19% 41% 17% 3	880
February	1st to 10th	Night	14% 5% 31% 35% 13% 2	800
	11th to 20th	Night	14% 4 27% 35% 17% 3	784
	21st to end	Night	12% 7% 27% 36% 15% 3	660
March	1st to 10th	Night	14% 5% 21% 38% 19% 2	800
	11th to 20th	Night	8% 5% 26% 38% 22% 1	800
	21st to end	Night	9% 7% 29% 39% 14% 2	880
April	1st to 10th	Night	12% 6% 25% 36% 20% 2	800
	11th to 20th	Night	10% 9% 31% 31% 15% 4	753
	21st to end	Night	8% 7% 32% 34% 16% 3	535
May	1st to 10th	Night	5% 8% 32% 35% 18% 2	380
	11th to 20th	Night	9% 6% 22% 35% 24% 4	374
	21st to end	Night	7% 5% 25% 36% 24% 4	411
June	1st to 10th	Night	8% 5% 29% 34% 21% 2	380
	11th to 20th	Night	6% 8% 35% 33% 15% 2	380
	21st to end	Night	4 6% 27% 35% 26% 2	380
July	1st to 10th	Night	2 4 23% 41% 27% 2	370
	11th to 20th	Night	2 4 25% 41% 26% 2	368
	21st to end	Night	1 4 19% 39% 34% 3	416
August	1st to 10th	Night	2 3 17% 36% 37% 5%	378
	11th to 20th	Night	3 2 16% 33% 38% 9%	474
	21st to end	Night	3 4 18% 38% 32% 5%	836
September	1st to 10th	Night	4 3 20% 35% 32% 6%	760
	11th to 20th	Night	5% 4 19% 29% 36% 8%	760
	21st to end	Night	7% 4 19% 36% 29% 5%	760
October	1st to 10th	Night	10% 5% 18% 38% 28% 2	760
	11th to 20th	Night	10% 4 20% 36% 25% 5%	760
	21st to end	Night	14% 4 24% 38% 16% 4	836
November	1st to 10th	Night	17% 5% 20% 43% 13% 1	780
	11th to 20th	Night	16% 7% 27% 32% 15% 3	800
	21st to end	Night	18% 4 20% 33% 22% 3	800
December	1st to 10th	Night	16% 5% 20% 37% 18% 4	800
	11th to 20th	Night	20% 5% 20% 40% 15% 1	800
	21st to end	Night	21% 5% 23% 41% 10% 1	880

Page generated at 2025-04-08 06:17:27. Version ac07

Copyright © 2025 Attilla Danko.