Talkeetna
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Talkeetna clear sky chart from 2005-11-06 to 2026-08-15.

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	20% 14% 4 9% 6% 5% 5% 4 5% 6% 23%	150267
	Night	16% 17% 5% 10% 5% 5% 4 3 4 5% 26%	140523
Transparency	Day	62% 8% 13% 11% 4 1	149908
	Night	59% 6% 10% 13% 9% 3	140468
Seeing	Day	24% 7% 19% 24% 19% 7%	20469
	Night	24% 8% 23% 26% 16% 3	24538

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	10% 19% 4 6% 4 5% 3 3 5% 4 37%	2361
	11th to 20th	Day	13% 21% 6% 12% 6% 5% 3 2 3 5% 23%	2747
	21st to end	Day	15% 13% 3 8% 5% 4 4 2 4 5% 38%	3793
February	1st to 10th	Day	10% 18% 4 7% 5% 3 3 2 4 5% 39%	1403
	11th to 20th	Day	14% 25% 5% 9% 5% 5% 4 4 4 5% 20%	1596
	21st to end	Day	8% 14% 4 11% 5% 5% 5% 4 5% 5% 34%	1489
March	1st to 10th	Day	6% 18% 7% 13% 7% 5% 4 3 4 4 28%	4452
	11th to 20th	Day	7% 17% 5% 13% 6% 5% 5% 4 6% 6% 26%	4801
	21st to end	Day	11% 17% 4 8% 5% 5% 5% 4 5% 6% 32%	6050
April	1st to 10th	Day	10% 17% 5% 10% 6% 5% 4 4 6% 7% 27%	2606
	11th to 20th	Day	9% 16% 4 9% 6% 4 5% 4 5% 5% 33%	2906
	21st to end	Day	12% 14% 4 9% 6% 5% 5% 4 5% 6% 31%	3014
May	1st to 10th	Day	19% 23% 5% 11% 6% 5% 5% 4 5% 5% 12%	9421
	11th to 20th	Day	17% 17% 6% 13% 7% 5% 4 4 4 5% 19%	9471
	21st to end	Day	18% 14% 5% 11% 7% 6% 6% 4 6% 7% 17%	11554
June	1st to 10th	Day	19% 12% 4 9% 6% 4 5% 4 6% 8% 23%	3780
	11th to 20th	Day	18% 10% 4 9% 6% 5% 4 4 6% 7% 25%	3780
	21st to end	Day	21% 10% 4 9% 6% 5% 6% 6% 7% 8% 20%	3780
July	1st to 10th	Day	27% 10% 4 9% 6% 5% 5% 4 5% 6% 19%	10620
	11th to 20th	Day	34% 13% 4 9% 6% 4 4 3 4 5% 15%	10569
	21st to end	Day	25% 8% 3 8% 5% 4 5% 4 6% 7% 24%	10546
August	1st to 10th	Day	39% 8% 3 7% 5% 4 4 3 5% 6% 16%	5366
	11th to 20th	Day	34% 10% 3 7% 4 4 4 3 5% 5% 21%	4727
	21st to end	Day	28% 10% 4 8% 5% 4 4 3 4 6% 23%	5038
September	1st to 10th	Day	36% 11% 4 9% 5% 4 3 2 3 4 17%	2503
	11th to 20th	Day	34% 14% 4 9% 4 4 4 3 4 3 16%	2400
	21st to end	Day	23% 12% 4 10% 5% 5% 4 3 5% 5% 25%	2124
October	1st to 10th	Day	19% 12% 3 7% 5% 5% 7% 5% 8% 7% 21%	3229
	11th to 20th	Day	15% 9% 3 7% 4 5% 5% 4 5% 6% 37%	2837
	21st to end	Day	19% 12% 3 8% 4 4 4 3 4 4 36%	2738
November	1st to 10th	Day	12% 17% 6% 8% 6% 4 5% 3 5% 5% 28%	1378
	11th to 20th	Day	12% 13% 3 6% 5% 4 4 4 5% 5% 40%	1227
	21st to end	Day	13% 17% 6% 12% 6% 5% 5% 3 5% 4 25%	1008
December	1st to 10th	Day	17% 20% 5% 12% 6% 4 3 3 5% 4 21%	1350
	11th to 20th	Day	8% 22% 9% 14% 6% 6% 4 4 4 6% 19%	1557
	21st to end	Day	6% 17% 7% 11% 5% 5% 4 3 5% 4 32%	2046
January	1st to 10th	Night	9% 18% 5% 9% 6% 5% 4 3 3 5% 34%	10564
	11th to 20th	Night	14% 22% 6% 12% 5% 4 3 3 3 4 24%	10196
	21st to end	Night	13% 14% 3 8% 5% 4 4 3 4 4 38%	10423
February	1st to 10th	Night	8% 18% 4 7% 5% 4 3 2 4 5% 40%	3214
	11th to 20th	Night	14% 25% 6% 10% 6% 4 4 3 4 5% 21%	2911
	21st to end	Night	8% 16% 5% 13% 6% 5% 5% 4 5% 5% 29%	2315
March	1st to 10th	Night	7% 20% 7% 12% 5% 4 4 3 4 5% 29%	5621
	11th to 20th	Night	8% 19% 6% 12% 6% 5% 4 4 6% 6% 25%	5375
	21st to end	Night	10% 19% 5% 8% 5% 4 4 3 5% 5% 31%	5123
April	1st to 10th	Night	10% 19% 6% 11% 6% 5% 5% 4 5% 6% 22%	2011
	11th to 20th	Night	8% 16% 4 9% 7% 6% 5% 5% 6% 5% 29%	1663
	21st to end	Night	12% 14% 3 9% 7% 6% 6% 3 5% 4 30%	1603
May	1st to 10th	Night	19% 25% 6% 12% 5% 4 4 3 4 4 13%	3528
	11th to 20th	Night	15% 19% 6% 15% 7% 5% 5% 3 4 5% 16%	3401
	21st to end	Night	24% 17% 5% 10% 6% 5% 5% 3 5% 5% 14%	2644
June	1st to 10th	Night	18% 14% 6% 10% 8% 6% 5% 3 5% 6% 19%	840
	11th to 20th	Night	18% 10% 3 8% 7% 4 5% 5% 7% 8% 25%	840
	21st to end	Night	27% 8% 3 8% 7% 6% 5% 5% 7% 7% 17%	840
July	1st to 10th	Night	31% 11% 5% 11% 7% 5% 5% 4 6% 6% 11%	2370
	11th to 20th	Night	37% 10% 3 9% 6% 5% 5% 3 4 4 13%	2422
	21st to end	Night	26% 10% 3 10% 6% 6% 5% 3 5% 6% 21%	3570
August	1st to 10th	Night	40% 9% 3 6% 5% 4 4 4 4 6% 15%	2014
	11th to 20th	Night	36% 9% 3 6% 4 3 3 3 4 7% 22%	2419
	21st to end	Night	30% 12% 3 8% 5% 6% 5% 4 5% 6% 15%	2871
September	1st to 10th	Night	37% 12% 3 9% 5% 4 4 3 3 3 17%	1896
	11th to 20th	Night	35% 14% 5% 8% 4 4 5% 3 4 4 15%	2000
	21st to end	Night	26% 13% 4 8% 5% 4 5% 4 5% 6% 21%	2273
October	1st to 10th	Night	23% 15% 4 9% 5% 5% 5% 5% 6% 7% 17%	3951
	11th to 20th	Night	14% 10% 3 9% 6% 5% 5% 4 5% 7% 32%	4311
	21st to end	Night	18% 13% 4 8% 5% 4 4 3 5% 5% 29%	5063
November	1st to 10th	Night	14% 18% 6% 9% 5% 4 4 3 5% 5% 27%	3137
	11th to 20th	Night	13% 13% 3 7% 5% 4 4 3 4 6% 37%	3393
	21st to end	Night	13% 18% 5% 10% 6% 5% 4 3 4 4 27%	3607
December	1st to 10th	Night	20% 20% 6% 10% 6% 4 4 3 5% 4 19%	6060
	11th to 20th	Night	8% 25% 8% 12% 5% 5% 4 3 4 4 21%	6880
	21st to end	Night	6% 18% 6% 12% 6% 6% 5% 3 5% 5% 28%	9174

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	47% 7% 9% 10% 17% 10%	2361
	11th to 20th	Day	60% 6% 10% 14% 9% 2	2762
	21st to end	Day	47% 5% 9% 18% 16% 5%	3794
February	1st to 10th	Day	47% 5% 11% 16% 14% 6%	1403
	11th to 20th	Day	65% 5% 10% 9% 9% 2	1603
	21st to end	Day	51% 9% 8% 17% 12% 3	1489
March	1st to 10th	Day	58% 4 8% 9% 16% 6%	4452
	11th to 20th	Day	54% 7% 11% 12% 13% 2	4801
	21st to end	Day	52% 7% 12% 17% 9% 3	6050
April	1st to 10th	Day	55% 9% 15% 15% 5% 1	2606
	11th to 20th	Day	50% 10% 12% 19% 8%	2906
	21st to end	Day	53% 7% 12% 20% 8%	3014
May	1st to 10th	Day	71% 8% 8% 11% 1	9421
	11th to 20th	Day	67% 9% 11% 12% 2	9474
	21st to end	Day	66% 9% 13% 11% 1	11555
June	1st to 10th	Day	59% 11% 16% 12% 2	3780
	11th to 20th	Day	58% 12% 16% 10% 3	3780
	21st to end	Day	63% 15% 17% 5%	3780
July	1st to 10th	Day	67% 10% 17% 6%	10531
	11th to 20th	Day	73% 8% 15% 4	10470
	21st to end	Day	59% 9% 21% 11%	10319
August	1st to 10th	Day	71% 9% 16% 4	5347
	11th to 20th	Day	65% 9% 14% 11% 1	4773
	21st to end	Day	64% 9% 17% 8% 2	5037
September	1st to 10th	Day	73% 9% 9% 6% 3	2503
	11th to 20th	Day	74% 8% 10% 7% 1	2400
	21st to end	Day	61% 10% 13% 13% 3	2124
October	1st to 10th	Day	55% 9% 15% 19% 2	3229
	11th to 20th	Day	46% 7% 16% 20% 10% 1	2837
	21st to end	Day	53% 6% 8% 26% 6% 1	2738
November	1st to 10th	Day	57% 7% 12% 14% 7% 2	1378
	11th to 20th	Day	46% 6% 9% 25% 14% 1	1227
	21st to end	Day	61% 7% 8% 8% 14% 2	1008
December	1st to 10th	Day	65% 7% 6% 14% 7% 1	1350
	11th to 20th	Day	66% 6% 11% 11% 5% 1	1560
	21st to end	Day	51% 5% 13% 13% 13% 5%	2046
January	1st to 10th	Night	50% 6% 8% 10% 14% 11%	10564
	11th to 20th	Night	64% 5% 7% 11% 11% 2	10244
	21st to end	Night	48% 5% 7% 17% 16% 7%	10423
February	1st to 10th	Night	48% 4 9% 18% 15% 7%	3214
	11th to 20th	Night	65% 6% 8% 10% 9% 3	2915
	21st to end	Night	56% 6% 9% 13% 13% 3	2315
March	1st to 10th	Night	55% 5% 9% 11% 15% 6%	5621
	11th to 20th	Night	56% 7% 9% 13% 15% 1	5377
	21st to end	Night	53% 7% 9% 18% 11% 2	5123
April	1st to 10th	Night	61% 7% 12% 14% 4 1	2011
	11th to 20th	Night	54% 9% 10% 18% 8%	1663
	21st to end	Night	55% 7% 13% 18% 7%	1603
May	1st to 10th	Night	72% 7% 8% 11% 1	3525
	11th to 20th	Night	68% 9% 10% 10% 2	3402
	21st to end	Night	71% 7% 11% 9% 1	2648
June	1st to 10th	Night	64% 11% 14% 9% 1	840
	11th to 20th	Night	57% 12% 16% 12% 3	840
	21st to end	Night	66% 13% 17% 5%	840
July	1st to 10th	Night	72% 10% 14% 3	2350
	11th to 20th	Night	74% 8% 14% 4	2398
	21st to end	Night	64% 7% 21% 8%	3493
August	1st to 10th	Night	68% 9% 18% 4	2008
	11th to 20th	Night	63% 9% 16% 11% 1	2439
	21st to end	Night	71% 8% 12% 6% 2	2871
September	1st to 10th	Night	74% 8% 9% 8% 2	1896
	11th to 20th	Night	72% 8% 9% 10% 1	2000
	21st to end	Night	66% 7% 11% 13% 3	2273
October	1st to 10th	Night	62% 7% 12% 15% 3	3951
	11th to 20th	Night	49% 7% 14% 18% 11% 1	4311
	21st to end	Night	55% 7% 11% 19% 8%	5063
November	1st to 10th	Night	58% 7% 12% 15% 7% 2	3137
	11th to 20th	Night	47% 6% 11% 24% 12%	3393
	21st to end	Night	59% 6% 9% 11% 12% 3	3607
December	1st to 10th	Night	66% 5% 7% 13% 7% 1	6060
	11th to 20th	Night	65% 6% 12% 10% 6% 1	6876
	21st to end	Night	53% 5% 13% 13% 11% 4	9174

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	15% 10% 29% 31% 13% 2	110
	11th to 20th	Day	22% 14% 26% 22% 13% 3	242
	21st to end	Day	25% 13% 23% 24% 13% 3	352
February	1st to 10th	Day	15% 11% 25% 24% 17% 8%	320
	11th to 20th	Day	24% 12% 24% 23% 15% 2	403
	21st to end	Day	16% 11% 28% 25% 13% 6%	355
March	1st to 10th	Day	17% 11% 27% 25% 16% 5%	430
	11th to 20th	Day	13% 8% 25% 29% 19% 7%	507
	21st to end	Day	13% 9% 23% 24% 22% 10%	704
April	1st to 10th	Day	15% 9% 24% 28% 16% 8%	659
	11th to 20th	Day	17% 8% 18% 27% 21% 9%	740
	21st to end	Day	17% 5% 17% 30% 26% 5%	750
May	1st to 10th	Day	19% 8% 21% 25% 23% 5%	753
	11th to 20th	Day	19% 9% 20% 28% 19% 5%	775
	21st to end	Day	22% 6% 22% 28% 19% 4	1048
June	1st to 10th	Day	23% 6% 17% 26% 23% 5%	990
	11th to 20th	Day	19% 6% 17% 27% 24% 7%	990
	21st to end	Day	21% 5% 13% 22% 28% 11%	990
July	1st to 10th	Day	23% 6% 13% 27% 23% 8%	976
	11th to 20th	Day	30% 5% 16% 24% 19% 6%	972
	21st to end	Day	29% 3 17% 22% 21% 9%	953
August	1st to 10th	Day	34% 6% 14% 22% 16% 7%	776
	11th to 20th	Day	30% 8% 19% 21% 16% 6%	736
	21st to end	Day	36% 5% 15% 18% 18% 8%	803
September	1st to 10th	Day	39% 5% 16% 16% 17% 7%	646
	11th to 20th	Day	39% 6% 12% 17% 16% 10%	620
	21st to end	Day	28% 8% 15% 21% 18% 10%	437
October	1st to 10th	Day	34% 7% 17% 21% 14% 7%	420
	11th to 20th	Day	26% 8% 19% 21% 19% 6%	420
	21st to end	Day	27% 7% 21% 26% 14% 4	462
November	1st to 10th	Day	23% 7% 25% 24% 17% 4	392
	11th to 20th	Day	17% 9% 22% 30% 16% 6%	287
	21st to end	Day	18% 13% 21% 30% 13% 5%	110
December	1st to 10th	Day	24% 13% 20% 36% 6% 1	110
	11th to 20th	Day	17% 14% 32% 27% 7% 3	110
	21st to end	Day	27% 12% 26% 21% 12% 2	121
January	1st to 10th	Night	15% 13% 25% 30% 15% 3	1060
	11th to 20th	Night	22% 12% 27% 26% 11% 2	1060
	21st to end	Night	25% 10% 29% 25% 11% 1	1059
February	1st to 10th	Night	16% 12% 27% 26% 17% 2	950
	11th to 20th	Night	25% 12% 28% 26% 9% 1	934
	21st to end	Night	16% 11% 29% 31% 12% 2	676
March	1st to 10th	Night	16% 11% 31% 27% 14% 1	740
	11th to 20th	Night	12% 6% 31% 32% 16% 2	740
	21st to end	Night	16% 7% 23% 25% 23% 6%	705
April	1st to 10th	Night	18% 7% 24% 26% 20% 5%	630
	11th to 20th	Night	15% 7% 21% 29% 22% 6%	623
	21st to end	Night	17% 5% 14% 29% 31% 4	611
May	1st to 10th	Night	16% 9% 16% 27% 28% 4	420
	11th to 20th	Night	16% 6% 22% 32% 22% 2	383
	21st to end	Night	23% 7% 19% 29% 21% 1	228
June	1st to 10th	Night	24% 7% 19% 29% 22%	210
	11th to 20th	Night	21% 3 14% 38% 24% 1	210
	21st to end	Night	27% 7% 12% 28% 24% 1	210
July	1st to 10th	Night	23% 5% 19% 33% 18% 2	205
	11th to 20th	Night	35% 5% 17% 25% 17% 1	217
	21st to end	Night	31% 5% 17% 23% 21% 3	460
August	1st to 10th	Night	38% 4 15% 23% 17% 2	418
	11th to 20th	Night	37% 7% 13% 25% 16% 2	505
	21st to end	Night	38% 3 13% 23% 18% 5%	660
September	1st to 10th	Night	39% 6% 14% 21% 18% 3	600
	11th to 20th	Night	41% 6% 11% 20% 19% 4	600
	21st to end	Night	32% 6% 17% 26% 15% 5%	650
October	1st to 10th	Night	41% 6% 17% 18% 14% 4	728
	11th to 20th	Night	28% 6% 22% 25% 17% 3	910
	21st to end	Night	25% 8% 23% 26% 15% 3	1001
November	1st to 10th	Night	24% 9% 25% 25% 15% 2	930
	11th to 20th	Night	21% 7% 28% 30% 13% 1	950
	21st to end	Night	24% 11% 23% 26% 14% 3	969
December	1st to 10th	Night	31% 8% 26% 23% 10% 2	1060
	11th to 20th	Night	21% 11% 30% 25% 10% 3	1060
	21st to end	Night	24% 12% 25% 25% 13% 2	1166

Page generated at 2026-08-11 23:37:17. Version ac07

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