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 2026-05-02.

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	16% 13% 4 9% 5% 4 4 3 4 5% 32%	136822
	Night	16% 15% 4 9% 5% 4 4 3 4 5% 30%	134432
Transparency	Day	50% 7% 12% 16% 12% 3	136543
	Night	50% 7% 12% 16% 11% 3	134289
Seeing	Day	25% 15% 26% 22% 10% 2	16954
	Night	25% 12% 20% 27% 16% 2	25470

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	28% 26% 5% 11% 6% 6% 4 2 2 2 7%	4723
	11th to 20th	Day	16% 16% 3 6% 4 3 3 2 4 5% 38%	4716
	21st to end	Day	23% 14% 4 10% 5% 5% 4 2 3 3 28%	5759
February	1st to 10th	Day	24% 22% 5% 10% 6% 5% 4 2 5% 5% 13%	1890
	11th to 20th	Day	22% 25% 6% 11% 6% 4 3 2 3 3 16%	1845
	21st to end	Day	22% 27% 5% 11% 5% 4 3 3 2 3 15%	1603
March	1st to 10th	Day	14% 21% 5% 14% 8% 6% 5% 4 4 4 14%	4921
	11th to 20th	Day	20% 23% 5% 10% 5% 4 3 2 2 2 23%	5110
	21st to end	Day	20% 20% 6% 16% 8% 6% 4 4 4 3 9%	5668
April	1st to 10th	Day	23% 21% 5% 10% 5% 5% 4 3 4 5% 13%	2520
	11th to 20th	Day	24% 19% 5% 10% 6% 4 3 2 2 4 21%	2536
	21st to end	Day	22% 17% 4 9% 6% 5% 5% 3 4 4 20%	2730
May	1st to 10th	Day	17% 13% 4 9% 5% 5% 4 3 4 5% 32%	6192
	11th to 20th	Day	14% 13% 5% 11% 7% 6% 5% 5% 5% 7% 23%	6277
	21st to end	Day	16% 13% 4 10% 6% 6% 5% 4 5% 6% 27%	6903
June	1st to 10th	Day	24% 11% 4 7% 5% 4 4 3 4 6% 28%	2800
	11th to 20th	Day	20% 14% 5% 10% 6% 5% 5% 4 6% 5% 19%	2941
	21st to end	Day	13% 8% 3 7% 5% 4 5% 4 6% 7% 38%	3000
July	1st to 10th	Day	4 5% 2 5% 3 3 3 3 4 5% 64%	6740
	11th to 20th	Day	4 4 1 2 2 2 2 2 4 6% 71%	6320
	21st to end	Day	7% 4 1 4 3 3 4 4 5% 7% 59%	6859
August	1st to 10th	Day	4 4 2 4 3 3 3 2 5% 8% 61%	4222
	11th to 20th	Day	8% 6% 3 8% 6% 6% 6% 5% 7% 8% 38%	4156
	21st to end	Day	11% 8% 3 7% 4 5% 4 4 5% 6% 43%	4488
September	1st to 10th	Day	7% 6% 3 7% 3 4 4 4 5% 7% 51%	2400
	11th to 20th	Day	13% 8% 3 7% 5% 4 5% 4 6% 6% 39%	2362
	21st to end	Day	16% 9% 3 8% 3 4 4 3 4 6% 41%	2126
October	1st to 10th	Day	16% 8% 2 6% 3 3 3 3 5% 7% 44%	3280
	11th to 20th	Day	21% 11% 4 10% 6% 4 4 3 5% 6% 25%	3261
	21st to end	Day	22% 14% 3 10% 5% 5% 5% 3 5% 5% 21%	3526
November	1st to 10th	Day	30% 15% 4 10% 7% 4 5% 3 4 4 15%	1691
	11th to 20th	Day	29% 17% 5% 10% 5% 4 4 3 4 4 15%	1680
	21st to end	Day	25% 16% 4 9% 5% 4 5% 3 3 3 21%	1680
December	1st to 10th	Day	17% 13% 3 10% 6% 5% 4 3 3 4 32%	2700
	11th to 20th	Day	26% 19% 5% 12% 7% 6% 4 3 3 3 12%	3105
	21st to end	Day	25% 25% 5% 11% 6% 5% 4 3 3 3 10%	4092
January	1st to 10th	Night	26% 24% 6% 13% 6% 5% 3 3 3 3 8%	8172
	11th to 20th	Night	14% 17% 4 7% 4 3 3 2 3 4 37%	8182
	21st to end	Night	22% 15% 4 9% 4 3 3 2 4 4 29%	8449
February	1st to 10th	Night	20% 20% 6% 12% 7% 5% 5% 2 4 4 16%	2730
	11th to 20th	Night	18% 22% 4 12% 6% 5% 4 3 3 3 20%	2662
	21st to end	Night	18% 24% 5% 11% 6% 5% 3 2 4 3 18%	2202
March	1st to 10th	Night	13% 18% 6% 13% 8% 6% 5% 3 4 5% 18%	5190
	11th to 20th	Night	16% 22% 5% 10% 6% 4 4 3 3 3 25%	5109
	21st to end	Night	20% 26% 6% 13% 6% 5% 4 2 4 4 10%	5549
April	1st to 10th	Night	19% 20% 6% 11% 6% 5% 4 2 4 4 18%	2100
	11th to 20th	Night	16% 19% 4 10% 7% 6% 4 3 4 6% 22%	2031
	21st to end	Night	17% 14% 4 10% 6% 5% 4 3 5% 6% 24%	1890
May	1st to 10th	Night	16% 13% 3 7% 4 4 4 3 4 5% 36%	3797
	11th to 20th	Night	11% 19% 4 10% 6% 6% 5% 4 5% 6% 23%	3616
	21st to end	Night	10% 15% 4 10% 7% 6% 6% 4 6% 7% 25%	3972
June	1st to 10th	Night	17% 9% 3 9% 6% 6% 5% 3 4 6% 32%	1600
	11th to 20th	Night	13% 13% 3 8% 6% 5% 5% 5% 6% 9% 28%	1452
	21st to end	Night	8% 7% 3 8% 5% 4 5% 4 6% 8% 44%	1400
July	1st to 10th	Night	1 4 2 6% 4 3 4 3 5% 6% 62%	3216
	11th to 20th	Night	2 3 1 3 2 3 3 2 4 5% 72%	3640
	21st to end	Night	3 3 2 5% 4 3 4 3 6% 9% 58%	3969
August	1st to 10th	Night	2 3 1 3 3 3 3 3 5% 9% 63%	2938
	11th to 20th	Night	6% 7% 3 7% 4 5% 5% 4 5% 7% 47%	2902
	21st to end	Night	10% 7% 2 5% 4 4 4 3 5% 7% 48%	3425
September	1st to 10th	Night	5% 5% 2 6% 3 5% 4 3 5% 7% 55%	2000
	11th to 20th	Night	9% 7% 3 7% 6% 5% 5% 4 5% 6% 44%	2035
	21st to end	Night	11% 7% 2 8% 4 4 4 3 5% 6% 44%	2273
October	1st to 10th	Night	10% 9% 2 6% 5% 4 4 3 4 7% 45%	3920
	11th to 20th	Night	15% 11% 3 9% 5% 5% 5% 4 6% 7% 30%	3897
	21st to end	Night	21% 16% 4 9% 6% 4 4 3 4 5% 24%	4284
November	1st to 10th	Night	27% 14% 4 11% 6% 4 4 3 4 5% 17%	2824
	11th to 20th	Night	27% 17% 4 11% 6% 4 3 3 4 3 18%	2940
	21st to end	Night	21% 16% 5% 10% 6% 5% 4 3 3 4 23%	2940
December	1st to 10th	Night	15% 13% 4 8% 5% 5% 5% 3 5% 5% 33%	4700
	11th to 20th	Night	29% 19% 5% 12% 7% 5% 3 3 3 3 10%	5320
	21st to end	Night	28% 20% 5% 11% 7% 5% 4 3 3 3 12%	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	80% 7% 4 5% 3	4723
	11th to 20th	Day	46% 7% 7% 14% 17% 11%	4740
	21st to end	Day	60% 5% 5% 11% 15% 4	5760
February	1st to 10th	Day	71% 6% 10% 9% 4	1890
	11th to 20th	Day	72% 6% 7% 9% 5% 1	1854
	21st to end	Day	72% 7% 7% 6% 6% 1	1603
March	1st to 10th	Day	66% 8% 12% 9% 5%	4921
	11th to 20th	Day	65% 4 7% 18% 5%	5110
	21st to end	Day	74% 8% 10% 6% 2	5668
April	1st to 10th	Day	68% 8% 12% 10% 2	2520
	11th to 20th	Day	65% 6% 9% 12% 7% 1	2536
	21st to end	Day	63% 7% 10% 13% 6% 1	2730
May	1st to 10th	Day	46% 7% 13% 22% 12%	6192
	11th to 20th	Day	48% 12% 20% 15% 6%	6280
	21st to end	Day	51% 10% 22% 15% 3	6904
June	1st to 10th	Day	55% 7% 15% 15% 8%	2800
	11th to 20th	Day	57% 11% 13% 14% 5%	2941
	21st to end	Day	39% 10% 16% 23% 9% 3	3000
July	1st to 10th	Day	20% 5% 13% 24% 19% 19%	6666
	11th to 20th	Day	14% 3 10% 23% 40% 10%	6245
	21st to end	Day	18% 5% 18% 35% 20% 3	6666
August	1st to 10th	Day	19% 5% 12% 24% 29% 11%	4206
	11th to 20th	Day	34% 9% 19% 22% 12% 4	4195
	21st to end	Day	36% 7% 13% 22% 18% 5%	4487
September	1st to 10th	Day	29% 7% 14% 24% 17% 9%	2400
	11th to 20th	Day	40% 10% 12% 18% 15% 5%	2362
	21st to end	Day	44% 7% 12% 18% 16% 4	2126
October	1st to 10th	Day	37% 5% 10% 27% 19% 2	3280
	11th to 20th	Day	54% 8% 13% 13% 12% 1	3261
	21st to end	Day	57% 7% 10% 16% 10%	3526
November	1st to 10th	Day	70% 7% 9% 10% 3 1	1691
	11th to 20th	Day	70% 6% 8% 8% 5% 2	1680
	21st to end	Day	65% 8% 7% 7% 12%	1680
December	1st to 10th	Day	53% 6% 8% 11% 21% 2	2700
	11th to 20th	Day	75% 7% 9% 7% 2	3108
	21st to end	Day	75% 9% 10% 4 2	4092
January	1st to 10th	Night	75% 7% 8% 6% 4 1	8172
	11th to 20th	Night	47% 7% 7% 14% 17% 8%	8220
	21st to end	Night	59% 4 5% 11% 18% 5%	8449
February	1st to 10th	Night	67% 9% 8% 11% 4 1	2730
	11th to 20th	Night	64% 8% 9% 10% 7% 2	2664
	21st to end	Night	66% 7% 9% 11% 6% 1	2202
March	1st to 10th	Night	61% 8% 13% 12% 5% 1	5190
	11th to 20th	Night	58% 7% 12% 16% 6%	5110
	21st to end	Night	72% 10% 9% 8% 1	5549
April	1st to 10th	Night	64% 7% 14% 12% 3	2100
	11th to 20th	Night	56% 8% 14% 13% 8% 2	2031
	21st to end	Night	53% 10% 13% 16% 7% 1	1890
May	1st to 10th	Night	39% 7% 15% 28% 11%	3794
	11th to 20th	Night	42% 11% 23% 15% 7% 1	3616
	21st to end	Night	42% 15% 25% 14% 3	3972
June	1st to 10th	Night	46% 9% 18% 20% 7% 1	1600
	11th to 20th	Night	41% 11% 21% 22% 5%	1452
	21st to end	Night	29% 8% 23% 28% 9% 4	1400
July	1st to 10th	Night	13% 6% 15% 28% 19% 20%	3181
	11th to 20th	Night	12% 4 9% 26% 33% 16%	3592
	21st to end	Night	13% 5% 21% 37% 19% 5%	3857
August	1st to 10th	Night	12% 6% 14% 26% 28% 15%	2929
	11th to 20th	Night	21% 8% 28% 27% 10% 6%	2929
	21st to end	Night	28% 6% 19% 22% 20% 4	3425
September	1st to 10th	Night	23% 8% 15% 25% 19% 10%	2000
	11th to 20th	Night	34% 10% 14% 19% 15% 8%	2035
	21st to end	Night	34% 8% 15% 18% 18% 6%	2273
October	1st to 10th	Night	33% 6% 11% 29% 19% 1	3920
	11th to 20th	Night	46% 7% 19% 17% 10% 2	3897
	21st to end	Night	54% 7% 11% 17% 10% 1	4284
November	1st to 10th	Night	65% 7% 10% 11% 6% 1	2824
	11th to 20th	Night	68% 8% 9% 8% 6% 2	2940
	21st to end	Night	61% 8% 8% 8% 12% 2	2940
December	1st to 10th	Night	47% 6% 9% 16% 21% 1	4700
	11th to 20th	Night	76% 6% 7% 6% 4	5316
	21st to end	Night	73% 8% 10% 7% 1	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	44% 21% 20% 9% 5% 1	220
	11th to 20th	Day	30% 19% 26% 11% 10% 3	220
	21st to end	Day	36% 16% 19% 20% 9% 1	442
February	1st to 10th	Day	40% 18% 20% 13% 8% 1	430
	11th to 20th	Day	41% 20% 23% 12% 4	425
	21st to end	Day	41% 21% 22% 11% 6%	380
March	1st to 10th	Day	35% 19% 28% 13% 5%	540
	11th to 20th	Day	37% 20% 23% 13% 6% 2	540
	21st to end	Day	40% 19% 21% 14% 5% 1	594
April	1st to 10th	Day	37% 16% 21% 16% 7% 2	540
	11th to 20th	Day	33% 19% 25% 14% 7% 2	532
	21st to end	Day	29% 19% 27% 17% 6% 1	540
May	1st to 10th	Day	21% 21% 27% 20% 9% 2	508
	11th to 20th	Day	29% 15% 27% 18% 9% 2	528
	21st to end	Day	22% 16% 27% 23% 9% 3	573
June	1st to 10th	Day	25% 14% 26% 22% 12% 2	530
	11th to 20th	Day	23% 21% 32% 19% 5% 1	671
	21st to end	Day	12% 12% 33% 30% 11% 2	730
July	1st to 10th	Day	11% 8% 34% 35% 10% 3	707
	11th to 20th	Day	8% 11% 30% 35% 14% 3	524
	21st to end	Day	6% 6% 26% 39% 17% 4	575
August	1st to 10th	Day	9% 7% 25% 37% 16% 7%	527
	11th to 20th	Day	7% 5% 25% 37% 19% 7%	517
	21st to end	Day	10% 10% 31% 30% 15% 4	583
September	1st to 10th	Day	8% 9% 28% 35% 16% 3	530
	11th to 20th	Day	15% 11% 29% 28% 13% 4	530
	21st to end	Day	20% 15% 24% 27% 13% 2	530
October	1st to 10th	Day	22% 13% 25% 23% 15% 2	530
	11th to 20th	Day	28% 15% 20% 22% 13% 3	530
	21st to end	Day	32% 17% 24% 15% 8% 3	563
November	1st to 10th	Day	40% 20% 20% 14% 5%	243
	11th to 20th	Day	32% 22% 25% 11% 7% 3	220
	21st to end	Day	31% 15% 21% 23% 6% 3	220
December	1st to 10th	Day	34% 15% 26% 15% 7% 2	220
	11th to 20th	Day	40% 22% 20% 14% 5%	220
	21st to end	Day	40% 18% 21% 16% 5%	242
January	1st to 10th	Night	42% 17% 17% 13% 10% 1	840
	11th to 20th	Night	33% 14% 19% 19% 14% 2	840
	21st to end	Night	30% 12% 19% 26% 12% 2	924
February	1st to 10th	Night	29% 16% 20% 21% 12% 1	840
	11th to 20th	Night	31% 15% 19% 22% 12% 1	824
	21st to end	Night	32% 17% 18% 25% 7%	692
March	1st to 10th	Night	28% 17% 20% 22% 11% 1	840
	11th to 20th	Night	32% 16% 19% 23% 10%	840
	21st to end	Night	34% 18% 18% 21% 9% 1	924
April	1st to 10th	Night	29% 13% 20% 23% 13% 2	840
	11th to 20th	Night	25% 14% 24% 25% 11% 1	783
	21st to end	Night	24% 14% 19% 30% 13% 1	630
May	1st to 10th	Night	18% 14% 22% 30% 15% 1	473
	11th to 20th	Night	19% 8% 18% 32% 21% 2	394
	21st to end	Night	18% 9% 20% 32% 18% 1	433
June	1st to 10th	Night	19% 8% 21% 35% 16% 1	400
	11th to 20th	Night	16% 11% 26% 33% 14% 1	400
	21st to end	Night	10% 7% 20% 41% 21% 1	400
July	1st to 10th	Night	4 4 22% 41% 28% 1	390
	11th to 20th	Night	5% 5% 25% 44% 21% 1	388
	21st to end	Night	3 3 18% 44% 30% 2	438
August	1st to 10th	Night	5% 4 15% 38% 33% 5%	597
	11th to 20th	Night	8% 2 12% 39% 35% 4	594
	21st to end	Night	10% 6% 18% 37% 27% 3	762
September	1st to 10th	Night	7% 4 20% 39% 28% 2	800
	11th to 20th	Night	11% 5% 20% 32% 27% 6%	800
	21st to end	Night	15% 8% 18% 35% 22% 3	800
October	1st to 10th	Night	19% 7% 20% 31% 21% 3	800
	11th to 20th	Night	23% 9% 17% 28% 20% 4	800
	21st to end	Night	29% 11% 20% 23% 15% 3	880
November	1st to 10th	Night	33% 13% 19% 24% 11% 1	820
	11th to 20th	Night	36% 13% 22% 19% 9% 1	840
	21st to end	Night	27% 15% 21% 23% 12% 2	840
December	1st to 10th	Night	29% 11% 23% 23% 13% 2	840
	11th to 20th	Night	38% 15% 20% 17% 8% 1	840
	21st to end	Night	43% 17% 19% 14% 6% 1	924

Page generated at 2026-04-28 23:21:41. Version ac07

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