Sunrise Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sunrise Point clear sky chart from 2005-11-06 to 2026-03-18.

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% 14% 5% 9% 5% 4 4 4 5% 7% 38%	135570
	Night	4 12% 5% 10% 6% 5% 5% 4 6% 8% 35%	134620
Transparency	Day	42% 8% 11% 19% 15% 5%	135295
	Night	43% 9% 12% 17% 14% 6%	134473
Seeing	Day	19% 23% 29% 19% 8% 2	16297
	Night	14% 19% 28% 25% 12% 2	25139

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	3 13% 9% 16% 8% 7% 5% 5% 8% 11% 14%	4723
	11th to 20th	Day	2 9% 4 10% 4 4 5% 4 6% 6% 45%	4716
	21st to end	Day	4 18% 6% 10% 4 5% 4 4 6% 7% 33%	5306
February	1st to 10th	Day	6% 18% 9% 15% 6% 6% 6% 5% 5% 6% 17%	1890
	11th to 20th	Day	5% 20% 9% 15% 8% 6% 5% 4 3 5% 21%	1845
	21st to end	Day	5% 21% 9% 18% 7% 6% 4 3 3 5% 17%	1672
March	1st to 10th	Day	2 16% 7% 16% 5% 5% 6% 5% 6% 8% 25%	4656
	11th to 20th	Day	3 19% 10% 13% 6% 6% 5% 3 4 4 27%	5078
	21st to end	Day	5% 25% 10% 13% 7% 5% 5% 5% 6% 7% 12%	5722
April	1st to 10th	Day	8% 25% 9% 14% 6% 5% 5% 3 5% 6% 15%	2400
	11th to 20th	Day	6% 25% 8% 11% 7% 4 4 3 3 4 25%	2372
	21st to end	Day	6% 24% 7% 12% 6% 5% 3 3 5% 5% 23%	2625
May	1st to 10th	Day	6% 18% 5% 6% 4 4 3 2 4 6% 41%	6320
	11th to 20th	Day	7% 17% 3 7% 5% 5% 5% 4 6% 9% 31%	6277
	21st to end	Day	8% 20% 5% 8% 5% 4 5% 3 5% 7% 30%	6903
June	1st to 10th	Day	15% 15% 3 9% 4 5% 5% 4 6% 6% 29%	2800
	11th to 20th	Day	11% 15% 4 9% 6% 5% 6% 5% 6% 7% 26%	2807
	21st to end	Day	9% 8% 3 6% 4 4 5% 4 5% 8% 44%	3000
July	1st to 10th	Day	2 3 1 3 2 2 2 2 3 4 74%	6417
	11th to 20th	Day	2 3 1 2 2 2 2 2 3 4 77%	6320
	21st to end	Day	4 3 1 3 3 2 4 3 5% 6% 66%	6874
August	1st to 10th	Day	2 3 1 4 2 3 3 3 5% 7% 66%	4488
	11th to 20th	Day	5% 4 2 5% 3 4 4 4 6% 8% 55%	4156
	21st to end	Day	8% 7% 2 6% 4 4 4 3 4 6% 52%	4393
September	1st to 10th	Day	7% 6% 2 5% 3 4 4 4 5% 7% 55%	2400
	11th to 20th	Day	10% 9% 2 7% 4 4 4 4 6% 6% 44%	2400
	21st to end	Day	10% 12% 3 7% 4 3 4 3 5% 5% 45%	2128
October	1st to 10th	Day	8% 9% 2 5% 3 3 3 4 5% 7% 50%	3280
	11th to 20th	Day	8% 11% 3 8% 6% 5% 5% 4 7% 10% 34%	3261
	21st to end	Day	7% 16% 6% 10% 5% 5% 4 3 6% 7% 30%	3330
November	1st to 10th	Day	11% 24% 5% 12% 6% 6% 5% 4 5% 5% 18%	1754
	11th to 20th	Day	8% 26% 7% 12% 6% 4 4 4 5% 5% 19%	1680
	21st to end	Day	6% 21% 7% 14% 6% 6% 5% 3 3 6% 24%	1680
December	1st to 10th	Day	4 14% 5% 11% 5% 5% 4 4 6% 6% 36%	2700
	11th to 20th	Day	4 16% 7% 15% 8% 8% 7% 5% 6% 7% 18%	3105
	21st to end	Day	3 18% 8% 15% 7% 6% 6% 5% 7% 8% 16%	4092
January	1st to 10th	Night	3 13% 8% 16% 9% 8% 8% 5% 7% 9% 14%	8172
	11th to 20th	Night	2 8% 3 8% 4 4 4 4 6% 10% 47%	8182
	21st to end	Night	2 14% 5% 12% 6% 6% 6% 5% 7% 7% 31%	8863
February	1st to 10th	Night	5% 16% 7% 13% 9% 7% 6% 5% 6% 8% 19%	2730
	11th to 20th	Night	4 15% 6% 14% 8% 6% 6% 5% 5% 6% 25%	2662
	21st to end	Night	5% 17% 9% 15% 8% 6% 6% 5% 5% 5% 20%	2134
March	1st to 10th	Night	2 9% 5% 14% 8% 7% 7% 6% 9% 11% 25%	5456
	11th to 20th	Night	2 13% 6% 13% 6% 5% 6% 5% 6% 9% 29%	5076
	21st to end	Night	5% 18% 9% 15% 7% 6% 5% 5% 7% 10% 14%	5240
April	1st to 10th	Night	5% 18% 9% 16% 8% 7% 6% 4 5% 6% 17%	2000
	11th to 20th	Night	5% 19% 7% 10% 6% 6% 6% 4 5% 5% 27%	1979
	21st to end	Night	6% 18% 6% 10% 7% 7% 6% 5% 6% 6% 21%	1772
May	1st to 10th	Night	7% 14% 6% 8% 4 4 4 3 4 5% 42%	3640
	11th to 20th	Night	4 9% 4 8% 6% 7% 6% 5% 7% 11% 33%	3616
	21st to end	Night	5% 15% 7% 10% 6% 6% 6% 5% 6% 8% 26%	3972
June	1st to 10th	Night	12% 14% 5% 9% 5% 5% 5% 4 4 6% 32%	1600
	11th to 20th	Night	8% 15% 3 10% 5% 6% 5% 3 6% 8% 31%	1582
	21st to end	Night	6% 8% 2 7% 5% 4 4 4 7% 7% 46%	1400
July	1st to 10th	Night	1 2 1 3 3 2 2 2 3 5% 76%	3520
	11th to 20th	Night	2 2 1 2 2 2 2 2 3 4 78%	3640
	21st to end	Night	2 2 1 2 2 2 3 2 4 6% 74%	3969
August	1st to 10th	Night	2 2 1 3 2 3 2 2 4 6% 73%	2662
	11th to 20th	Night	5% 5% 2 3 3 3 3 3 5% 9% 59%	2902
	21st to end	Night	5% 6% 2 6% 3 4 3 3 5% 8% 55%	3524
September	1st to 10th	Night	6% 5% 1 5% 3 4 5% 3 6% 7% 55%	2000
	11th to 20th	Night	7% 8% 3 8% 5% 5% 4 4 5% 5% 46%	2000
	21st to end	Night	7% 10% 3 8% 5% 4 4 4 6% 7% 44%	2269
October	1st to 10th	Night	6% 7% 2 6% 3 4 4 3 5% 9% 52%	3920
	11th to 20th	Night	6% 12% 4 6% 6% 5% 6% 5% 7% 8% 35%	3897
	21st to end	Night	8% 12% 4 9% 5% 4 5% 4 8% 11% 30%	4473
November	1st to 10th	Night	9% 20% 6% 12% 7% 6% 6% 4 5% 5% 21%	2762
	11th to 20th	Night	6% 18% 7% 14% 8% 6% 6% 4 6% 5% 21%	2940
	21st to end	Night	5% 18% 7% 15% 7% 5% 5% 4 5% 6% 23%	2940
December	1st to 10th	Night	3 12% 4 10% 5% 5% 4 4 6% 8% 39%	4700
	11th to 20th	Night	5% 15% 8% 15% 8% 7% 7% 5% 7% 7% 15%	5320
	21st to end	Night	4 18% 7% 17% 7% 7% 7% 5% 6% 8% 15%	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	56% 11% 12% 13% 7% 1	4723
	11th to 20th	Day	36% 6% 9% 16% 20% 12%	4740
	21st to end	Day	48% 8% 7% 14% 16% 8%	5307
February	1st to 10th	Day	62% 11% 10% 10% 6% 1	1890
	11th to 20th	Day	63% 9% 9% 10% 7% 2	1854
	21st to end	Day	66% 8% 8% 9% 7% 1	1672
March	1st to 10th	Day	51% 9% 15% 12% 9% 5%	4656
	11th to 20th	Day	56% 7% 8% 22% 7%	5078
	21st to end	Day	63% 13% 12% 9% 3	5722
April	1st to 10th	Day	66% 10% 12% 10% 2	2400
	11th to 20th	Day	59% 9% 11% 13% 7% 1	2372
	21st to end	Day	60% 9% 11% 14% 6% 1	2625
May	1st to 10th	Day	41% 5% 11% 24% 17% 2	6320
	11th to 20th	Day	42% 8% 21% 21% 7%	6280
	21st to end	Day	51% 9% 16% 18% 6%	6904
June	1st to 10th	Day	51% 10% 15% 14% 9% 1	2800
	11th to 20th	Day	50% 12% 17% 12% 8% 1	2807
	21st to end	Day	34% 10% 18% 23% 14% 2	3000
July	1st to 10th	Day	15% 5% 7% 24% 24% 25%	6348
	11th to 20th	Day	13% 3 7% 21% 31% 25%	6245
	21st to end	Day	17% 6% 9% 30% 30% 8%	6681
August	1st to 10th	Day	15% 6% 11% 20% 32% 16%	4471
	11th to 20th	Day	22% 7% 13% 39% 17% 2	4195
	21st to end	Day	31% 7% 10% 20% 26% 5%	4392
September	1st to 10th	Day	26% 7% 12% 26% 24% 5%	2400
	11th to 20th	Day	38% 7% 11% 21% 18% 5%	2400
	21st to end	Day	39% 7% 14% 21% 14% 4	2128
October	1st to 10th	Day	31% 4 10% 29% 23% 3	3280
	11th to 20th	Day	41% 8% 14% 19% 17% 1	3261
	21st to end	Day	48% 8% 9% 18% 12% 5%	3330
November	1st to 10th	Day	63% 9% 10% 12% 4 2	1754
	11th to 20th	Day	65% 8% 9% 10% 6% 2	1680
	21st to end	Day	60% 8% 8% 11% 9% 4	1680
December	1st to 10th	Day	45% 7% 9% 17% 18% 5%	2700
	11th to 20th	Day	58% 14% 9% 12% 6%	3108
	21st to end	Day	62% 8% 10% 13% 7% 1	4092
January	1st to 10th	Night	58% 12% 11% 9% 9% 1	8172
	11th to 20th	Night	31% 8% 13% 15% 19% 14%	8220
	21st to end	Night	47% 8% 8% 11% 15% 11%	8863
February	1st to 10th	Night	60% 11% 11% 10% 7% 2	2730
	11th to 20th	Night	54% 11% 12% 11% 9% 4	2664
	21st to end	Night	63% 10% 10% 10% 6% 1	2134
March	1st to 10th	Night	44% 10% 15% 15% 11% 5%	5456
	11th to 20th	Night	45% 8% 14% 23% 10% 1	5077
	21st to end	Night	57% 17% 11% 11% 4	5240
April	1st to 10th	Night	63% 12% 11% 10% 4	2000
	11th to 20th	Night	52% 11% 12% 15% 9% 1	1979
	21st to end	Night	55% 13% 11% 14% 7% 1	1772
May	1st to 10th	Night	42% 5% 9% 22% 18% 3	3637
	11th to 20th	Night	38% 8% 20% 23% 10% 1	3616
	21st to end	Night	48% 13% 16% 18% 4 1	3972
June	1st to 10th	Night	49% 10% 14% 18% 9% 1	1600
	11th to 20th	Night	44% 10% 18% 17% 9% 2	1582
	21st to end	Night	30% 10% 18% 26% 14% 2	1400
July	1st to 10th	Night	12% 5% 9% 23% 22% 29%	3480
	11th to 20th	Night	11% 3 7% 22% 26% 30%	3592
	21st to end	Night	10% 3 13% 30% 30% 13%	3857
August	1st to 10th	Night	13% 5% 9% 19% 37% 18%	2654
	11th to 20th	Night	22% 7% 16% 33% 20% 4	2929
	21st to end	Night	26% 7% 13% 24% 24% 6%	3524
September	1st to 10th	Night	23% 9% 14% 23% 24% 7%	2000
	11th to 20th	Night	36% 10% 9% 20% 18% 7%	2000
	21st to end	Night	35% 9% 15% 19% 16% 6%	2269
October	1st to 10th	Night	29% 5% 10% 31% 22% 3	3920
	11th to 20th	Night	40% 9% 11% 25% 14% 2	3897
	21st to end	Night	41% 9% 10% 22% 15% 4	4473
November	1st to 10th	Night	61% 9% 11% 12% 6% 1	2762
	11th to 20th	Night	63% 10% 9% 11% 7% 2	2940
	21st to end	Night	57% 11% 9% 10% 11% 4	2940
December	1st to 10th	Night	41% 8% 11% 15% 21% 4	4700
	11th to 20th	Night	61% 13% 9% 10% 6%	5316
	21st to end	Night	60% 12% 12% 11% 5%	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	27% 32% 23% 11% 6% 1	220
	11th to 20th	Day	17% 30% 26% 17% 10%	220
	21st to end	Day	19% 33% 21% 17% 9%	284
February	1st to 10th	Day	25% 35% 24% 12% 4 1	430
	11th to 20th	Day	26% 30% 27% 14% 2	425
	21st to end	Day	29% 26% 27% 14% 3	416
March	1st to 10th	Day	21% 31% 30% 15% 2	540
	11th to 20th	Day	27% 27% 24% 15% 5% 1	529
	21st to end	Day	28% 32% 26% 12% 3	550
April	1st to 10th	Day	28% 28% 26% 12% 5% 1	500
	11th to 20th	Day	24% 32% 26% 12% 5% 1	492
	21st to end	Day	23% 28% 27% 14% 8% 1	500
May	1st to 10th	Day	21% 24% 30% 19% 5% 1	503
	11th to 20th	Day	27% 16% 31% 15% 7% 3	528
	21st to end	Day	25% 21% 25% 19% 9% 2	573
June	1st to 10th	Day	21% 22% 27% 20% 9% 1	530
	11th to 20th	Day	21% 28% 32% 13% 6% 1	537
	21st to end	Day	13% 20% 33% 22% 10% 2	730
July	1st to 10th	Day	8% 17% 38% 30% 7% 1	571
	11th to 20th	Day	6% 14% 40% 27% 10% 2	524
	21st to end	Day	3 13% 31% 35% 14% 3	575
August	1st to 10th	Day	6% 12% 32% 29% 14% 6%	527
	11th to 20th	Day	6% 9% 31% 32% 16% 5%	517
	21st to end	Day	8% 18% 33% 25% 10% 4	583
September	1st to 10th	Day	9% 15% 37% 27% 9% 3	530
	11th to 20th	Day	14% 19% 32% 24% 11% 1	530
	21st to end	Day	17% 23% 28% 22% 9% 1	530
October	1st to 10th	Day	20% 23% 26% 19% 11% 1	530
	11th to 20th	Day	24% 22% 26% 15% 10% 3	530
	21st to end	Day	28% 24% 26% 13% 8% 2	443
November	1st to 10th	Day	26% 29% 26% 13% 5%	278
	11th to 20th	Day	31% 25% 20% 13% 9% 2	220
	21st to end	Day	22% 24% 25% 17% 11% 1	220
December	1st to 10th	Day	26% 23% 23% 12% 13% 3	220
	11th to 20th	Day	25% 35% 20% 16% 4	220
	21st to end	Day	24% 24% 29% 17% 6% 1	242
January	1st to 10th	Night	21% 30% 27% 15% 7% 1	840
	11th to 20th	Night	18% 25% 28% 20% 8% 2	840
	21st to end	Night	14% 24% 28% 25% 8% 1	924
February	1st to 10th	Night	16% 24% 32% 20% 7% 1	840
	11th to 20th	Night	16% 23% 27% 26% 8%	824
	21st to end	Night	23% 21% 31% 19% 5% 1	692
March	1st to 10th	Night	13% 24% 31% 23% 9% 1	840
	11th to 20th	Night	14% 26% 29% 21% 8%	828
	21st to end	Night	17% 26% 33% 17% 6% 1	880
April	1st to 10th	Night	15% 23% 29% 24% 7% 2	800
	11th to 20th	Night	14% 22% 32% 22% 8% 2	791
	21st to end	Night	13% 20% 34% 22% 10% 1	572
May	1st to 10th	Night	13% 21% 25% 28% 12% 2	400
	11th to 20th	Night	13% 14% 24% 28% 20% 2	394
	21st to end	Night	12% 13% 27% 30% 17% 2	433
June	1st to 10th	Night	15% 15% 25% 31% 13% 1	400
	11th to 20th	Night	11% 17% 34% 27% 12%	400
	21st to end	Night	9% 9% 25% 37% 21% 1	400
July	1st to 10th	Night	3 6% 26% 44% 21% 1	390
	11th to 20th	Night	4 5% 26% 46% 19% 1	388
	21st to end	Night	3 4 21% 42% 29% 2	438
August	1st to 10th	Night	4 5% 18% 39% 31% 4	425
	11th to 20th	Night	4 4 18% 34% 32% 8%	594
	21st to end	Night	6% 9% 24% 35% 23% 3	822
September	1st to 10th	Night	8% 7% 24% 34% 24% 3	800
	11th to 20th	Night	9% 9% 23% 29% 24% 6%	800
	21st to end	Night	11% 14% 24% 31% 19% 2	800
October	1st to 10th	Night	15% 13% 26% 28% 17% 2	800
	11th to 20th	Night	18% 15% 28% 22% 14% 3	800
	21st to end	Night	20% 21% 26% 22% 8% 3	880
November	1st to 10th	Night	20% 21% 33% 20% 5%	820
	11th to 20th	Night	23% 25% 26% 19% 6% 1	840
	21st to end	Night	16% 25% 28% 21% 10% 1	840
December	1st to 10th	Night	17% 22% 28% 24% 7% 1	840
	11th to 20th	Night	20% 25% 32% 16% 6%	840
	21st to end	Night	19% 29% 32% 15% 4	924

Page generated at 2026-03-14 23:23:51. Version ac07

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