Squirrel Cove
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Squirrel Cove clear sky chart from 2005-11-06 to 2026-01-17.

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	22% 9% 3 7% 4 4 4 3 5% 6% 34%	131493
	Night	28% 10% 3 7% 4 4 4 3 4 5% 28%	128893
Transparency	Day	31% 41% 10% 13% 4 1	131189
	Night	37% 40% 10% 10% 3	128775
Seeing	Day	26% 11% 22% 24% 15% 3	17185
	Night	33% 8% 20% 24% 14% 1	25241

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	41% 15% 3 8% 5% 4 3 3 4 5% 9%	3249
	11th to 20th	Day	22% 11% 3 9% 6% 4 3 3 5% 7% 28%	3201
	21st to end	Day	46% 11% 3 6% 4 3 2 2 2 4 15%	3746
February	1st to 10th	Day	32% 13% 3 8% 4 5% 3 4 4 5% 19%	1800
	11th to 20th	Day	31% 10% 2 6% 5% 5% 4 3 4 5% 24%	1755
	21st to end	Day	28% 12% 4 6% 5% 5% 5% 3 5% 6% 23%	1485
March	1st to 10th	Day	27% 14% 4 8% 5% 4 4 4 5% 5% 21%	4714
	11th to 20th	Day	22% 12% 4 9% 6% 5% 5% 4 5% 6% 23%	5000
	21st to end	Day	26% 12% 4 10% 5% 5% 4 3 4 5% 20%	5486
April	1st to 10th	Day	26% 11% 3 8% 6% 5% 5% 3 4 7% 24%	2415
	11th to 20th	Day	23% 8% 3 7% 5% 4 5% 4 5% 6% 31%	2568
	21st to end	Day	24% 10% 2 6% 4 4 3 2 5% 6% 32%	2600
May	1st to 10th	Day	13% 8% 3 7% 5% 4 5% 4 5% 6% 39%	6319
	11th to 20th	Day	15% 8% 3 7% 4 4 5% 4 6% 10% 32%	6340
	21st to end	Day	24% 11% 3 6% 4 4 4 3 4 6% 29%	7405
June	1st to 10th	Day	18% 8% 3 6% 5% 4 4 5% 5% 7% 34%	3000
	11th to 20th	Day	13% 8% 3 9% 6% 5% 5% 4 7% 9% 32%	3000
	21st to end	Day	17% 7% 2 6% 4 4 4 4 5% 6% 42%	3000
July	1st to 10th	Day	9% 4 1 4 3 3 3 3 5% 7% 59%	6780
	11th to 20th	Day	4 2 1 3 2 2 2 2 4 6% 71%	6780
	21st to end	Day	9% 4 2 4 3 3 3 3 5% 7% 57%	7375
August	1st to 10th	Day	5% 2 1 2 2 2 2 3 4 6% 70%	4389
	11th to 20th	Day	12% 6% 2 5% 3 4 5% 4 6% 8% 44%	4156
	21st to end	Day	15% 5% 2 5% 3 4 4 3 4 8% 48%	4664
September	1st to 10th	Day	12% 4 2 5% 3 4 4 3 5% 6% 52%	2425
	11th to 20th	Day	22% 6% 2 5% 4 4 3 2 5% 6% 41%	2297
	21st to end	Day	27% 6% 2 5% 5% 4 5% 3 5% 6% 32%	2172
October	1st to 10th	Day	29% 10% 3 9% 6% 4 4 3 4 5% 23%	3280
	11th to 20th	Day	34% 6% 2 7% 5% 4 4 3 5% 6% 24%	3261
	21st to end	Day	34% 12% 4 8% 5% 3 4 3 5% 5% 19%	3189
November	1st to 10th	Day	38% 10% 4 8% 5% 4 4 3 4 4 16%	1648
	11th to 20th	Day	37% 11% 4 7% 5% 5% 4 2 4 4 18%	1680
	21st to end	Day	39% 11% 3 8% 5% 3 4 3 3 4 17%	1664
December	1st to 10th	Day	30% 11% 5% 13% 6% 4 4 2 4 4 18%	2360
	11th to 20th	Day	49% 13% 3 7% 4 3 3 2 3 3 10%	2715
	21st to end	Day	42% 16% 4 8% 5% 4 3 3 3 3 10%	3575
January	1st to 10th	Night	42% 13% 4 9% 5% 4 4 3 3 3 9%	6916
	11th to 20th	Night	26% 10% 3 7% 4 5% 5% 4 5% 6% 27%	6829
	21st to end	Night	40% 11% 3 6% 4 3 4 3 4 5% 17%	7201
February	1st to 10th	Night	36% 12% 4 7% 5% 4 4 3 3 5% 20%	2600
	11th to 20th	Night	28% 12% 3 6% 4 4 3 3 5% 5% 28%	2532
	21st to end	Night	30% 13% 3 7% 4 3 3 3 4 4 25%	2145
March	1st to 10th	Night	30% 12% 3 8% 5% 5% 4 3 4 5% 21%	5171
	11th to 20th	Night	21% 12% 4 9% 5% 5% 5% 3 4 4 26%	4999
	21st to end	Night	35% 11% 3 8% 5% 4 4 3 3 4 19%	5489
April	1st to 10th	Night	26% 10% 4 7% 5% 4 4 3 5% 5% 25%	1982
	11th to 20th	Night	22% 10% 3 6% 6% 5% 5% 4 5% 7% 29%	1781
	21st to end	Night	25% 9% 3 8% 5% 4 4 3 5% 5% 29%	1800
May	1st to 10th	Night	15% 7% 2 6% 4 4 4 4 5% 6% 43%	3640
	11th to 20th	Night	16% 7% 3 7% 4 4 5% 4 6% 9% 34%	3539
	21st to end	Night	28% 11% 3 7% 4 4 5% 3 4 5% 25%	3470
June	1st to 10th	Night	19% 11% 3 7% 4 3 5% 3 6% 6% 33%	1400
	11th to 20th	Night	15% 9% 4 7% 7% 5% 5% 4 6% 7% 31%	1400
	21st to end	Night	17% 7% 3 7% 5% 4 4 4 6% 6% 38%	1400
July	1st to 10th	Night	8% 5% 2 5% 4 4 4 4 5% 5% 54%	3180
	11th to 20th	Night	4 2 1 2 2 2 2 2 4 5% 73%	3180
	21st to end	Night	11% 4 2 4 2 3 3 3 5% 7% 57%	3468
August	1st to 10th	Night	5% 3 1 3 3 3 2 3 5% 5% 69%	2761
	11th to 20th	Night	11% 5% 2 6% 4 5% 5% 3 6% 8% 45%	2902
	21st to end	Night	14% 6% 2 6% 3 4 3 3 5% 6% 48%	3245
September	1st to 10th	Night	10% 6% 2 6% 3 4 4 3 4 7% 52%	1975
	11th to 20th	Night	21% 6% 2 6% 4 4 3 3 4 5% 42%	2100
	21st to end	Night	26% 7% 3 6% 4 3 3 2 4 5% 36%	2227
October	1st to 10th	Night	31% 9% 3 6% 4 4 3 3 4 5% 26%	3920
	11th to 20th	Night	36% 7% 3 6% 4 4 4 3 4 6% 23%	3897
	21st to end	Night	31% 11% 3 8% 4 4 3 3 4 6% 22%	4609
November	1st to 10th	Night	40% 10% 3 8% 4 4 3 3 4 4 15%	2870
	11th to 20th	Night	35% 12% 4 8% 6% 4 4 2 4 4 18%	2940
	21st to end	Night	37% 11% 3 8% 5% 4 3 3 4 4 18%	2952
December	1st to 10th	Night	33% 12% 4 10% 6% 4 4 3 4 4 16%	5040
	11th to 20th	Night	46% 14% 4 7% 4 3 3 2 3 3 10%	5710
	21st to end	Night	43% 15% 4 8% 4 4 3 2 3 3 11%	7623

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	55% 30% 7% 7% 1	3249
	11th to 20th	Day	35% 33% 13% 13% 5%	3222
	21st to end	Day	53% 31% 9% 7%	3746
February	1st to 10th	Day	24% 63% 3 4 3 3	1800
	11th to 20th	Day	26% 63% 3 5% 1 2	1764
	21st to end	Day	23% 63% 6% 4 3 1	1485
March	1st to 10th	Day	47% 33% 6% 9% 4	4714
	11th to 20th	Day	41% 33% 7% 16% 2	5000
	21st to end	Day	49% 34% 9% 6% 2	5486
April	1st to 10th	Day	24% 64% 4 5% 2	2415
	11th to 20th	Day	23% 63% 6% 5% 2 1	2568
	21st to end	Day	20% 64% 6% 7% 3	2600
May	1st to 10th	Day	30% 32% 13% 17% 7%	6319
	11th to 20th	Day	33% 35% 15% 15% 2	6343
	21st to end	Day	41% 33% 12% 9% 5%	7406
June	1st to 10th	Day	17% 64% 8% 8% 2	3000
	11th to 20th	Day	16% 64% 8% 9% 4	3000
	21st to end	Day	18% 63% 7% 9% 2	3000
July	1st to 10th	Day	18% 28% 15% 22% 13% 5%	6706
	11th to 20th	Day	9% 28% 17% 31% 14% 1	6699
	21st to end	Day	21% 29% 21% 21% 7%	7168
August	1st to 10th	Day	8% 37% 8% 38% 10% 1	4372
	11th to 20th	Day	26% 42% 18% 9% 4	4195
	21st to end	Day	22% 40% 16% 17% 5%	4663
September	1st to 10th	Day	17% 60% 8% 12% 4	2425
	11th to 20th	Day	22% 58% 7% 8% 5%	2297
	21st to end	Day	23% 60% 5% 8% 3 1	2172
October	1st to 10th	Day	46% 39% 8% 5% 2	3280
	11th to 20th	Day	39% 39% 7% 13% 2	3261
	21st to end	Day	45% 39% 6% 9% 2	3189
November	1st to 10th	Day	35% 55% 5% 3 2	1648
	11th to 20th	Day	31% 55% 5% 5% 2 1	1680
	21st to end	Day	33% 56% 4 4 2 1	1664
December	1st to 10th	Day	44% 41% 6% 7% 2	2360
	11th to 20th	Day	60% 32% 3 3 1	2718
	21st to end	Day	58% 31% 7% 2 1	3575
January	1st to 10th	Night	57% 29% 6% 7% 2	6916
	11th to 20th	Night	36% 33% 12% 13% 4 3	6870
	21st to end	Night	49% 31% 11% 9%	7201
February	1st to 10th	Night	25% 62% 2 4 6% 2	2600
	11th to 20th	Night	26% 62% 5% 3 3 1	2534
	21st to end	Night	23% 63% 4 6% 3 1	2145
March	1st to 10th	Night	45% 32% 8% 11% 4	5171
	11th to 20th	Night	41% 33% 6% 17% 2	5000
	21st to end	Night	51% 33% 7% 6% 3	5489
April	1st to 10th	Night	23% 64% 5% 6% 2	1982
	11th to 20th	Night	22% 63% 6% 6% 2 2	1781
	21st to end	Night	22% 63% 6% 6% 3	1800
May	1st to 10th	Night	26% 31% 15% 21% 7%	3637
	11th to 20th	Night	32% 36% 21% 9% 2	3539
	21st to end	Night	45% 33% 10% 10% 1	3470
June	1st to 10th	Night	17% 64% 8% 8% 2	1400
	11th to 20th	Night	16% 64% 8% 8% 4	1400
	21st to end	Night	19% 61% 8% 10% 1 1	1400
July	1st to 10th	Night	22% 28% 17% 21% 11% 2	3145
	11th to 20th	Night	7% 29% 24% 30% 10%	3138
	21st to end	Night	21% 28% 27% 20% 4	3370
August	1st to 10th	Night	7% 36% 6% 43% 8% 1	2754
	11th to 20th	Night	26% 41% 21% 8% 3	2929
	21st to end	Night	24% 39% 20% 13% 4	3245
September	1st to 10th	Night	17% 60% 9% 10% 5%	1975
	11th to 20th	Night	22% 59% 7% 7% 4 1	2100
	21st to end	Night	22% 59% 8% 7% 3	2227
October	1st to 10th	Night	42% 40% 9% 6% 3	3920
	11th to 20th	Night	43% 38% 10% 9% 1	3897
	21st to end	Night	41% 41% 9% 8% 2	4609
November	1st to 10th	Night	35% 56% 3 3 2	2870
	11th to 20th	Night	32% 56% 4 4 3 1	2940
	21st to end	Night	31% 56% 4 5% 3 1	2952
December	1st to 10th	Night	47% 40% 7% 5% 1	5040
	11th to 20th	Night	56% 34% 5% 3 1	5706
	21st to end	Night	59% 30% 5% 4 1	7623

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% 8% 23% 14% 4 5%	220
	11th to 20th	Day	39% 16% 14% 18% 12% 1	212
	21st to end	Day	43% 11% 16% 17% 11% 2	300
February	1st to 10th	Day	40% 14% 22% 14% 9% 2	400
	11th to 20th	Day	32% 13% 25% 20% 9% 2	395
	21st to end	Day	35% 15% 26% 18% 6% 1	331
March	1st to 10th	Day	33% 11% 20% 21% 11% 3	466
	11th to 20th	Day	34% 14% 18% 18% 13% 2	500
	21st to end	Day	33% 15% 24% 18% 8% 2	550
April	1st to 10th	Day	32% 17% 21% 19% 8% 1	500
	11th to 20th	Day	26% 13% 28% 21% 11% 2	492
	21st to end	Day	28% 14% 23% 21% 12% 2	500
May	1st to 10th	Day	19% 11% 29% 28% 13% 1	503
	11th to 20th	Day	21% 9% 24% 30% 15% 2	551
	21st to end	Day	21% 12% 25% 28% 13% 1	790
June	1st to 10th	Day	24% 14% 26% 25% 10% 1	730
	11th to 20th	Day	17% 14% 28% 27% 13% 1	730
	21st to end	Day	18% 9% 23% 34% 14% 2	730
July	1st to 10th	Day	14% 8% 25% 31% 18% 3	721
	11th to 20th	Day	10% 7% 26% 34% 20% 3	718
	21st to end	Day	9% 6% 17% 35% 29% 4	794
August	1st to 10th	Day	11% 3 17% 33% 30% 7%	527
	11th to 20th	Day	10% 6% 20% 36% 24% 3	517
	21st to end	Day	15% 8% 19% 34% 19% 4	583
September	1st to 10th	Day	15% 8% 22% 29% 22% 4	530
	11th to 20th	Day	27% 8% 17% 22% 23% 3	530
	21st to end	Day	31% 9% 21% 22% 16% 1	530
October	1st to 10th	Day	28% 11% 22% 19% 15% 5%	530
	11th to 20th	Day	38% 10% 19% 17% 13% 4	530
	21st to end	Day	36% 14% 19% 17% 10% 3	433
November	1st to 10th	Day	43% 12% 21% 16% 5% 2	220
	11th to 20th	Day	41% 14% 16% 10% 12% 6%	220
	21st to end	Day	45% 11% 17% 11% 10% 6%	220
December	1st to 10th	Day	41% 9% 13% 16% 14% 8%	220
	11th to 20th	Day	48% 12% 15% 13% 10% 2	220
	21st to end	Day	47% 7% 22% 19% 4 1	242
January	1st to 10th	Night	47% 11% 19% 15% 7% 1	950
	11th to 20th	Night	43% 8% 18% 21% 9%	930
	21st to end	Night	42% 6% 19% 19% 12% 2	976
February	1st to 10th	Night	41% 9% 22% 22% 5% 1	800
	11th to 20th	Night	34% 8% 21% 26% 11% 1	784
	21st to end	Night	37% 13% 24% 18% 7% 1	660
March	1st to 10th	Night	38% 10% 21% 19% 12% 1	800
	11th to 20th	Night	36% 13% 20% 20% 11% 1	800
	21st to end	Night	36% 11% 20% 20% 12% 1	880
April	1st to 10th	Night	32% 9% 21% 25% 12% 1	777
	11th to 20th	Night	30% 8% 25% 26% 11%	593
	21st to end	Night	30% 9% 24% 26% 10% 1	600
May	1st to 10th	Night	22% 7% 25% 32% 14% 1	400
	11th to 20th	Night	24% 7% 19% 33% 16% 2	394
	21st to end	Night	25% 7% 21% 32% 14% 1	433
June	1st to 10th	Night	24% 9% 23% 33% 11% 1	400
	11th to 20th	Night	18% 10% 22% 34% 17%	400
	21st to end	Night	19% 6% 24% 32% 19% 1	400
July	1st to 10th	Night	14% 6% 21% 34% 24% 1	390
	11th to 20th	Night	11% 5% 21% 37% 25% 2	388
	21st to end	Night	10% 3 13% 40% 31% 3	438
August	1st to 10th	Night	11% 4 10% 37% 36% 2	487
	11th to 20th	Night	12% 5% 17% 37% 27% 3	594
	21st to end	Night	17% 6% 14% 38% 23% 2	660
September	1st to 10th	Night	13% 4 16% 37% 26% 3	775
	11th to 20th	Night	24% 5% 14% 25% 28% 5%	800
	21st to end	Night	32% 8% 17% 25% 18% 2	800
October	1st to 10th	Night	30% 7% 18% 27% 17% 1	800
	11th to 20th	Night	37% 5% 17% 24% 15% 2	800
	21st to end	Night	40% 9% 20% 20% 9% 2	880
November	1st to 10th	Night	46% 10% 19% 18% 7%	820
	11th to 20th	Night	40% 10% 24% 17% 6% 2	840
	21st to end	Night	42% 9% 20% 18% 9% 2	847
December	1st to 10th	Night	37% 8% 21% 21% 9% 3	950
	11th to 20th	Night	49% 9% 18% 15% 8% 1	950
	21st to end	Night	46% 12% 22% 17% 4	1045

Page generated at 2026-01-13 22:14:28. Version ac07

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