Salmonberry
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Salmonberry clear sky chart from 2005-11-06 to 2025-01-07.

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	18% 14% 4 9% 5% 4 4 3 4 5% 30%	109720
	Night	17% 15% 4 9% 5% 5% 4 3 4 5% 28%	107936
Transparency	Day	51% 8% 11% 15% 11% 3	109482
	Night	52% 8% 12% 15% 10% 3	107820
Seeing	Day	25% 16% 25% 22% 10% 2	15272
	Night	25% 12% 19% 27% 16% 2	23783

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	29% 27% 5% 11% 5% 6% 4 3 2 2 7%	2587
	11th to 20th	Day	29% 21% 4 8% 4 3 3 2 3 4 19%	2516
	21st to end	Day	28% 21% 5% 12% 6% 5% 4 2 2 3 12%	3091
February	1st to 10th	Day	26% 21% 5% 10% 6% 5% 4 2 4 5% 13%	1710
	11th to 20th	Day	22% 25% 5% 11% 6% 4 3 2 3 3 16%	1665
	21st to end	Day	22% 28% 5% 11% 5% 4 3 2 3 4 13%	1455
March	1st to 10th	Day	15% 22% 5% 15% 8% 6% 4 4 4 4 13%	3344
	11th to 20th	Day	19% 19% 4 7% 5% 3 3 2 2 3 34%	3490
	21st to end	Day	23% 20% 5% 14% 7% 6% 4 3 3 3 12%	3872
April	1st to 10th	Day	25% 22% 5% 10% 5% 5% 4 3 4 5% 13%	2280
	11th to 20th	Day	26% 19% 5% 10% 6% 4 3 2 2 4 19%	2292
	21st to end	Day	24% 18% 5% 9% 6% 5% 5% 3 4 4 18%	2470
May	1st to 10th	Day	21% 14% 4 9% 5% 5% 4 3 4 4 28%	4317
	11th to 20th	Day	12% 9% 4 8% 6% 5% 5% 5% 6% 8% 32%	4377
	21st to end	Day	21% 15% 4 11% 7% 6% 5% 4 5% 5% 18%	4813
June	1st to 10th	Day	25% 12% 4 8% 5% 4 4 3 4 5% 25%	2660
	11th to 20th	Day	21% 14% 5% 10% 6% 5% 5% 4 6% 5% 19%	2794
	21st to end	Day	13% 8% 3 7% 5% 4 4 4 6% 7% 38%	2850
July	1st to 10th	Day	5% 5% 1 4 3 3 3 3 4 5% 63%	4714
	11th to 20th	Day	6% 4 1 3 2 2 3 2 4 6% 66%	4420
	21st to end	Day	9% 5% 2 4 3 3 3 3 5% 7% 56%	4775
August	1st to 10th	Day	4 4 2 4 3 3 3 2 5% 8% 62%	4092
	11th to 20th	Day	8% 6% 3 8% 6% 6% 5% 5% 7% 8% 38%	4026
	21st to end	Day	11% 8% 3 7% 4 5% 4 4 5% 6% 43%	4350
September	1st to 10th	Day	7% 6% 3 7% 3 4 4 4 4 7% 52%	2280
	11th to 20th	Day	13% 8% 3 7% 5% 4 5% 4 6% 6% 38%	2244
	21st to end	Day	16% 9% 3 8% 4 4 4 3 4 5% 40%	2020
October	1st to 10th	Day	16% 8% 2 5% 3 3 3 3 5% 7% 44%	3180
	11th to 20th	Day	21% 12% 4 10% 6% 4 4 3 5% 6% 25%	3161
	21st to end	Day	22% 14% 3 10% 5% 5% 5% 3 5% 5% 22%	3417
November	1st to 10th	Day	29% 15% 4 10% 7% 4 5% 3 4 4 15%	1609
	11th to 20th	Day	29% 17% 5% 10% 5% 4 4 3 4 4 16%	1600
	21st to end	Day	25% 16% 4 9% 5% 4 5% 3 3 3 21%	1600
December	1st to 10th	Day	16% 13% 3 9% 6% 5% 4 3 3 4 33%	2620
	11th to 20th	Day	26% 19% 5% 12% 7% 6% 4 3 3 3 12%	3025
	21st to end	Day	25% 25% 6% 11% 6% 5% 4 3 3 3 10%	4004
January	1st to 10th	Night	27% 24% 5% 12% 6% 5% 3 3 3 3 9%	4490
	11th to 20th	Night	24% 22% 5% 10% 5% 4 4 2 3 4 16%	4382
	21st to end	Night	30% 20% 5% 11% 5% 4 3 3 3 3 12%	4573
February	1st to 10th	Night	21% 20% 6% 12% 7% 5% 4 2 4 4 15%	2470
	11th to 20th	Night	19% 22% 4 12% 5% 5% 4 3 3 3 20%	2402
	21st to end	Night	18% 25% 6% 11% 6% 5% 3 3 3 3 17%	1998
March	1st to 10th	Night	14% 20% 5% 12% 8% 6% 4 3 4 6% 17%	3528
	11th to 20th	Night	14% 18% 3 8% 4 3 3 3 3 4 37%	3489
	21st to end	Night	20% 26% 6% 12% 6% 5% 4 2 3 3 12%	3781
April	1st to 10th	Night	20% 21% 6% 11% 6% 5% 4 2 4 4 18%	1900
	11th to 20th	Night	17% 19% 4 10% 7% 5% 3 4 4 7% 21%	1836
	21st to end	Night	18% 15% 4 10% 6% 5% 4 3 5% 7% 22%	1710
May	1st to 10th	Night	20% 16% 4 8% 4 4 3 2 4 5% 32%	2646
	11th to 20th	Night	10% 12% 3 8% 5% 6% 5% 5% 6% 8% 32%	2516
	21st to end	Night	11% 19% 4 10% 8% 7% 6% 4 5% 6% 21%	2762
June	1st to 10th	Night	17% 10% 4 9% 6% 6% 5% 3 4 6% 31%	1520
	11th to 20th	Night	13% 13% 3 8% 6% 5% 5% 5% 6% 9% 27%	1380
	21st to end	Night	8% 7% 3 7% 5% 4 5% 4 6% 8% 45%	1330
July	1st to 10th	Night	2 4 2 5% 4 3 3 3 4 5% 64%	2242
	11th to 20th	Night	4 4 2 4 3 3 3 3 5% 6% 66%	2540
	21st to end	Night	3 4 2 6% 4 4 4 3 6% 8% 57%	2762
August	1st to 10th	Night	2 3 1 3 3 3 3 3 5% 10% 63%	2848
	11th to 20th	Night	5% 7% 3 7% 4 5% 5% 4 5% 7% 47%	2812
	21st to end	Night	10% 7% 2 5% 4 4 4 3 5% 7% 49%	3321
September	1st to 10th	Night	5% 5% 2 6% 3 5% 4 3 5% 7% 57%	1900
	11th to 20th	Night	9% 7% 3 8% 6% 5% 5% 4 6% 6% 43%	1933
	21st to end	Night	12% 7% 2 8% 4 4 5% 3 5% 7% 43%	2159
October	1st to 10th	Night	10% 9% 2 6% 5% 4 4 3 4 7% 45%	3800
	11th to 20th	Night	15% 10% 3 9% 5% 5% 5% 4 6% 7% 30%	3777
	21st to end	Night	21% 16% 4 9% 6% 4 4 3 4 5% 24%	4151
November	1st to 10th	Night	27% 14% 4 11% 6% 4 4 3 4 5% 18%	2686
	11th to 20th	Night	27% 17% 4 10% 6% 4 3 3 4 4 18%	2800
	21st to end	Night	21% 15% 5% 10% 6% 5% 4 3 3 4 24%	2800
December	1st to 10th	Night	14% 13% 4 7% 5% 5% 5% 3 5% 5% 34%	4560
	11th to 20th	Night	29% 19% 5% 12% 7% 5% 3 3 3 3 10%	5180
	21st to end	Night	28% 20% 5% 11% 7% 5% 4 3 3 3 11%	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	81% 9% 4 3 3	2587
	11th to 20th	Day	69% 7% 7% 10% 3 3	2540
	21st to end	Day	76% 7% 5% 6% 5%	3091
February	1st to 10th	Day	72% 6% 10% 9% 3	1710
	11th to 20th	Day	73% 7% 7% 8% 5% 1	1674
	21st to end	Day	73% 7% 8% 5% 5% 1	1455
March	1st to 10th	Day	68% 10% 10% 7% 4	3344
	11th to 20th	Day	56% 5% 8% 25% 6%	3490
	21st to end	Day	73% 9% 9% 6% 3	3872
April	1st to 10th	Day	70% 8% 11% 9% 2	2280
	11th to 20th	Day	67% 6% 8% 10% 7% 1	2292
	21st to end	Day	66% 7% 9% 11% 5% 1	2470
May	1st to 10th	Day	52% 9% 13% 15% 11%	4317
	11th to 20th	Day	38% 13% 23% 19% 8% 1	4380
	21st to end	Day	61% 12% 15% 11% 1	4814
June	1st to 10th	Day	57% 7% 15% 13% 7%	2660
	11th to 20th	Day	59% 11% 13% 12% 5%	2794
	21st to end	Day	38% 10% 16% 24% 9% 3	2850
July	1st to 10th	Day	21% 6% 8% 16% 21% 27%	4640
	11th to 20th	Day	17% 4 8% 20% 37% 14%	4345
	21st to end	Day	21% 5% 14% 29% 28% 4	4624
August	1st to 10th	Day	19% 5% 11% 24% 30% 11%	4076
	11th to 20th	Day	34% 9% 20% 22% 12% 4	4065
	21st to end	Day	36% 7% 13% 22% 18% 5%	4349
September	1st to 10th	Day	28% 7% 14% 24% 18% 9%	2280
	11th to 20th	Day	41% 10% 12% 17% 15% 5%	2244
	21st to end	Day	44% 7% 12% 17% 15% 4	2020
October	1st to 10th	Day	37% 5% 10% 27% 19% 2	3180
	11th to 20th	Day	54% 8% 13% 13% 12% 1	3161
	21st to end	Day	57% 7% 10% 16% 10%	3417
November	1st to 10th	Day	70% 7% 9% 10% 3 1	1609
	11th to 20th	Day	70% 6% 9% 8% 5% 2	1600
	21st to end	Day	65% 8% 7% 8% 12% 1	1600
December	1st to 10th	Day	52% 6% 8% 11% 21% 2	2620
	11th to 20th	Day	75% 7% 9% 7% 2	3028
	21st to end	Day	76% 9% 10% 4 2	4004
January	1st to 10th	Night	76% 9% 6% 5% 3 1	4490
	11th to 20th	Night	69% 9% 7% 10% 3 3	4420
	21st to end	Night	76% 5% 6% 6% 6% 1	4573
February	1st to 10th	Night	69% 8% 8% 11% 4 1	2470
	11th to 20th	Night	65% 8% 9% 10% 6% 2	2404
	21st to end	Night	68% 7% 9% 9% 5% 1	1998
March	1st to 10th	Night	64% 9% 12% 12% 3	3528
	11th to 20th	Night	48% 8% 12% 23% 8% 1	3490
	21st to end	Night	71% 10% 10% 8% 1	3781
April	1st to 10th	Night	66% 8% 13% 11% 4	1900
	11th to 20th	Night	57% 8% 14% 12% 7% 2	1836
	21st to end	Night	55% 10% 13% 14% 6% 1	1710
May	1st to 10th	Night	45% 8% 17% 20% 9% 1	2646
	11th to 20th	Night	30% 12% 25% 19% 11% 2	2516
	21st to end	Night	47% 20% 21% 10% 3	2762
June	1st to 10th	Night	47% 9% 17% 19% 7% 1	1520
	11th to 20th	Night	42% 12% 21% 20% 4	1380
	21st to end	Night	29% 8% 22% 28% 8% 4	1330
July	1st to 10th	Night	13% 7% 12% 19% 20% 29%	2207
	11th to 20th	Night	15% 5% 9% 20% 31% 20%	2492
	21st to end	Night	13% 5% 17% 31% 26% 8%	2674
August	1st to 10th	Night	12% 5% 13% 26% 28% 15%	2839
	11th to 20th	Night	21% 8% 29% 28% 11% 5%	2839
	21st to end	Night	28% 6% 19% 22% 20% 4	3321
September	1st to 10th	Night	22% 8% 14% 25% 20% 11%	1900
	11th to 20th	Night	35% 10% 14% 18% 15% 8%	1933
	21st to end	Night	34% 9% 15% 18% 18% 6%	2159
October	1st to 10th	Night	33% 6% 11% 30% 19% 2	3800
	11th to 20th	Night	46% 7% 19% 17% 10% 2	3777
	21st to end	Night	54% 7% 11% 17% 10% 1	4151
November	1st to 10th	Night	65% 8% 10% 11% 6% 1	2686
	11th to 20th	Night	67% 8% 9% 8% 6% 2	2800
	21st to end	Night	61% 8% 8% 8% 13% 2	2800
December	1st to 10th	Night	46% 7% 9% 16% 21% 1	4560
	11th to 20th	Night	76% 6% 7% 6% 4	5176
	21st to end	Night	73% 8% 10% 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	46% 21% 17% 10% 5% 1	192
	11th to 20th	Day	37% 21% 21% 10% 9% 3	180
	21st to end	Day	38% 16% 17% 20% 8% 1	378
February	1st to 10th	Day	40% 19% 17% 14% 9% 1	370
	11th to 20th	Day	42% 21% 22% 12% 3	365
	21st to end	Day	39% 23% 21% 12% 5%	328
March	1st to 10th	Day	36% 20% 28% 12% 4	460
	11th to 20th	Day	32% 20% 24% 15% 7% 2	460
	21st to end	Day	40% 21% 19% 14% 6% 1	506
April	1st to 10th	Day	38% 19% 20% 14% 8% 2	460
	11th to 20th	Day	35% 20% 23% 13% 7% 2	452
	21st to end	Day	31% 22% 25% 15% 6% 1	460
May	1st to 10th	Day	21% 22% 27% 19% 9% 2	463
	11th to 20th	Day	28% 14% 27% 18% 10% 2	488
	21st to end	Day	23% 16% 26% 23% 9% 2	529
June	1st to 10th	Day	26% 14% 25% 23% 11% 1	490
	11th to 20th	Day	23% 21% 31% 18% 5% 1	624
	21st to end	Day	11% 13% 33% 30% 11% 2	680
July	1st to 10th	Day	10% 9% 33% 36% 9% 3	658
	11th to 20th	Day	8% 12% 30% 34% 14% 2	484
	21st to end	Day	6% 7% 27% 39% 17% 4	531
August	1st to 10th	Day	8% 7% 25% 37% 15% 7%	487
	11th to 20th	Day	6% 5% 25% 38% 19% 7%	477
	21st to end	Day	9% 10% 32% 30% 15% 4	539
September	1st to 10th	Day	8% 10% 28% 36% 15% 3	490
	11th to 20th	Day	16% 11% 29% 27% 13% 4	490
	21st to end	Day	20% 15% 24% 26% 13% 2	490
October	1st to 10th	Day	23% 14% 23% 22% 16% 2	490
	11th to 20th	Day	27% 14% 20% 22% 14% 3	490
	21st to end	Day	32% 17% 24% 15% 9% 3	520
November	1st to 10th	Day	38% 20% 20% 15% 6%	221
	11th to 20th	Day	34% 21% 24% 12% 8% 3	200
	21st to end	Day	30% 16% 21% 23% 7% 4	200
December	1st to 10th	Day	30% 16% 29% 16% 8% 3	200
	11th to 20th	Day	36% 24% 22% 14% 6%	200
	21st to end	Day	43% 17% 19% 15% 5%	220
January	1st to 10th	Night	43% 16% 16% 13% 10% 2	784
	11th to 20th	Night	35% 14% 17% 18% 14% 2	760
	21st to end	Night	31% 12% 18% 25% 12% 2	836
February	1st to 10th	Night	31% 17% 19% 21% 12% 1	760
	11th to 20th	Night	31% 16% 18% 22% 12% 1	744
	21st to end	Night	32% 18% 18% 25% 7%	628
March	1st to 10th	Night	29% 18% 19% 22% 12% 1	760
	11th to 20th	Night	30% 16% 18% 25% 11% 1	760
	21st to end	Night	33% 19% 17% 21% 9% 1	836
April	1st to 10th	Night	31% 15% 20% 22% 12% 1	760
	11th to 20th	Night	25% 14% 24% 25% 11% 1	708
	21st to end	Night	25% 15% 17% 29% 13% 1	570
May	1st to 10th	Night	18% 14% 22% 30% 14% 1	447
	11th to 20th	Night	19% 9% 16% 33% 22% 2	374
	21st to end	Night	19% 10% 20% 32% 18% 1	411
June	1st to 10th	Night	20% 8% 21% 35% 16% 1	380
	11th to 20th	Night	17% 11% 24% 33% 15% 1	380
	21st to end	Night	11% 7% 20% 40% 22% 1	380
July	1st to 10th	Night	4 4 20% 42% 29% 1	370
	11th to 20th	Night	5% 5% 24% 44% 22% 1	368
	21st to end	Night	4 3 18% 44% 31% 2	416
August	1st to 10th	Night	4 4 14% 38% 35% 5%	567
	11th to 20th	Night	7% 2 11% 39% 36% 5%	564
	21st to end	Night	10% 6% 18% 37% 27% 3	724
September	1st to 10th	Night	7% 4 19% 39% 28% 2	760
	11th to 20th	Night	11% 5% 19% 31% 28% 6%	760
	21st to end	Night	15% 8% 18% 35% 21% 3	760
October	1st to 10th	Night	19% 6% 19% 31% 22% 3	760
	11th to 20th	Night	22% 9% 17% 28% 21% 4	760
	21st to end	Night	29% 11% 19% 22% 16% 3	836
November	1st to 10th	Night	32% 13% 19% 24% 11% 1	780
	11th to 20th	Night	36% 14% 21% 19% 9% 1	800
	21st to end	Night	27% 16% 20% 24% 12% 2	800
December	1st to 10th	Night	27% 11% 24% 23% 13% 2	800
	11th to 20th	Night	38% 15% 21% 17% 8% 1	800
	21st to end	Night	44% 17% 19% 13% 7% 1	880

Page generated at 2025-01-04 00:24:01. Version ac07

Copyright © 2025 Attilla Danko.