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 2025-04-11.

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	19% 14% 4 9% 6% 5% 4 4 5% 6% 24%	115463
	Night	15% 17% 5% 10% 5% 5% 4 3 5% 5% 26%	121574
Transparency	Day	60% 9% 13% 12% 5% 1	115152
	Night	59% 7% 11% 13% 9% 2	121535
Seeing	Day	24% 7% 19% 24% 20% 7%	18432
	Night	24% 8% 23% 26% 16% 3	23037

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	12% 19% 4 6% 4 5% 3 3 5% 5% 34%	1819
	11th to 20th	Day	10% 22% 6% 11% 5% 5% 4 3 4 5% 25%	2099
	21st to end	Day	18% 14% 3 8% 5% 4 3 3 4 5% 33%	2927
February	1st to 10th	Day	10% 18% 4 7% 5% 3 3 2 4 5% 40%	1336
	11th to 20th	Day	14% 25% 5% 9% 5% 4 4 4 4 5% 20%	1518
	21st to end	Day	8% 14% 4 11% 5% 6% 5% 5% 5% 5% 33%	1420
March	1st to 10th	Day	6% 18% 7% 14% 7% 5% 4 3 4 4 28%	4355
	11th to 20th	Day	7% 17% 6% 13% 6% 5% 5% 4 6% 6% 25%	4697
	21st to end	Day	11% 17% 4 9% 5% 5% 5% 4 5% 6% 31%	5919
April	1st to 10th	Day	10% 17% 5% 10% 6% 4 5% 4 6% 6% 26%	2481
	11th to 20th	Day	8% 15% 3 9% 6% 4 4 4 5% 5% 36%	2631
	21st to end	Day	10% 12% 3 9% 6% 5% 5% 4 6% 6% 33%	2726
May	1st to 10th	Day	14% 19% 6% 11% 7% 6% 5% 4 6% 6% 16%	5070
	11th to 20th	Day	10% 13% 5% 11% 7% 6% 5% 4 5% 6% 28%	5074
	21st to end	Day	19% 12% 4 9% 5% 5% 5% 4 6% 8% 23%	6170
June	1st to 10th	Day	19% 11% 4 9% 6% 4 5% 4 6% 8% 23%	3420
	11th to 20th	Day	19% 11% 4 9% 6% 6% 5% 4 6% 7% 23%	3420
	21st to end	Day	21% 10% 4 9% 6% 5% 6% 6% 6% 8% 20%	3420
July	1st to 10th	Day	33% 12% 4 9% 6% 5% 5% 3 4 5% 13%	5700
	11th to 20th	Day	32% 12% 4 8% 6% 5% 4 3 4 4 18%	5675
	21st to end	Day	26% 9% 3 8% 5% 5% 5% 4 5% 7% 23%	5658
August	1st to 10th	Day	40% 9% 3 7% 5% 4 4 3 5% 6% 15%	5046
	11th to 20th	Day	36% 10% 3 7% 4 4 3 3 4 5% 21%	4519
	21st to end	Day	28% 10% 4 8% 5% 4 4 3 5% 6% 24%	4884
September	1st to 10th	Day	35% 11% 4 9% 5% 4 4 2 3 4 18%	2379
	11th to 20th	Day	35% 14% 4 9% 4 4 4 3 4 3 16%	2280
	21st to end	Day	23% 12% 4 9% 5% 4 4 3 5% 5% 25%	2018
October	1st to 10th	Day	18% 12% 3 7% 6% 5% 7% 5% 8% 8% 21%	3130
	11th to 20th	Day	15% 9% 3 7% 4 5% 5% 4 5% 6% 37%	2750
	21st to end	Day	20% 11% 2 8% 4 4 4 3 4 4 36%	2653
November	1st to 10th	Day	13% 18% 6% 8% 5% 4 4 3 5% 5% 29%	1311
	11th to 20th	Day	12% 13% 3 6% 5% 4 4 4 5% 5% 40%	1169
	21st to end	Day	13% 18% 6% 11% 5% 5% 5% 3 5% 4 26%	960
December	1st to 10th	Day	17% 20% 5% 12% 7% 4 3 3 5% 4 20%	1310
	11th to 20th	Day	8% 23% 9% 15% 6% 6% 4 4 4 6% 17%	1517
	21st to end	Day	6% 17% 7% 11% 6% 5% 4 3 5% 4 32%	2002
January	1st to 10th	Night	10% 19% 5% 9% 5% 4 4 3 4 5% 31%	8146
	11th to 20th	Night	12% 22% 6% 12% 5% 4 3 3 3 4 25%	7827
	21st to end	Night	16% 15% 3 8% 5% 4 4 3 4 4 35%	8053
February	1st to 10th	Night	9% 18% 4 7% 5% 4 3 2 3 4 40%	3061
	11th to 20th	Night	14% 25% 5% 10% 6% 4 4 3 4 4 21%	2769
	21st to end	Night	8% 17% 5% 14% 6% 4 5% 4 5% 5% 27%	2208
March	1st to 10th	Night	7% 20% 7% 12% 5% 4 4 3 4 5% 29%	5498
	11th to 20th	Night	8% 20% 6% 12% 6% 5% 4 4 6% 6% 24%	5259
	21st to end	Night	10% 20% 5% 9% 5% 4 4 3 5% 5% 30%	5012
April	1st to 10th	Night	10% 20% 6% 12% 6% 5% 4 3 5% 6% 22%	1916
	11th to 20th	Night	8% 14% 4 8% 6% 5% 6% 5% 6% 6% 32%	1504
	21st to end	Night	11% 13% 3 8% 6% 6% 6% 3 6% 4 33%	1451
May	1st to 10th	Night	17% 20% 6% 12% 7% 6% 4 4 6% 5% 14%	1900
	11th to 20th	Night	10% 15% 5% 13% 7% 5% 5% 4 6% 6% 22%	1829
	21st to end	Night	21% 13% 3 9% 6% 5% 5% 4 6% 7% 21%	1412
June	1st to 10th	Night	18% 14% 5% 10% 8% 6% 6% 3 5% 7% 19%	760
	11th to 20th	Night	20% 11% 3 8% 7% 4 5% 5% 7% 7% 23%	760
	21st to end	Night	26% 8% 3 8% 7% 6% 5% 5% 7% 7% 18%	760
July	1st to 10th	Night	36% 11% 4 8% 6% 5% 4 3 6% 5% 12%	1270
	11th to 20th	Night	37% 11% 3 7% 5% 4 3 3 5% 5% 17%	1294
	21st to end	Night	28% 10% 3 10% 6% 5% 5% 3 5% 6% 21%	1911
August	1st to 10th	Night	40% 9% 3 6% 5% 4 4 4 4 6% 14%	1894
	11th to 20th	Night	37% 9% 3 6% 3 3 3 3 4 7% 22%	2318
	21st to end	Night	29% 12% 3 9% 6% 6% 5% 4 5% 6% 15%	2783
September	1st to 10th	Night	35% 12% 3 9% 5% 4 4 3 3 3 17%	1800
	11th to 20th	Night	35% 14% 5% 8% 4 4 4 3 4 4 16%	1900
	21st to end	Night	26% 13% 4 9% 5% 4 5% 4 5% 6% 22%	2159
October	1st to 10th	Night	22% 15% 4 9% 5% 5% 5% 5% 6% 7% 17%	3830
	11th to 20th	Night	14% 10% 3 9% 6% 5% 5% 4 5% 7% 33%	4178
	21st to end	Night	18% 12% 4 8% 5% 4 4 3 5% 5% 30%	4906
November	1st to 10th	Night	14% 18% 6% 9% 5% 4 4 3 5% 5% 27%	2984
	11th to 20th	Night	13% 13% 3 7% 5% 4 3 3 5% 6% 38%	3231
	21st to end	Night	13% 18% 5% 10% 6% 5% 4 3 4 4 28%	3435
December	1st to 10th	Night	20% 20% 6% 10% 5% 4 3 3 5% 5% 18%	5880
	11th to 20th	Night	9% 25% 8% 13% 5% 5% 4 3 4 4 19%	6700
	21st to end	Night	7% 18% 6% 12% 6% 6% 5% 3 5% 5% 27%	8976

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	48% 8% 11% 12% 13% 7%	1819
	11th to 20th	Day	56% 7% 12% 14% 9% 2	2114
	21st to end	Day	52% 5% 7% 9% 20% 6%	2927
February	1st to 10th	Day	47% 5% 11% 15% 15% 7%	1336
	11th to 20th	Day	65% 5% 10% 9% 9% 2	1525
	21st to end	Day	53% 9% 8% 18% 11% 2	1420
March	1st to 10th	Day	59% 4 8% 9% 15% 6%	4355
	11th to 20th	Day	55% 7% 11% 12% 13% 2	4697
	21st to end	Day	53% 7% 12% 16% 9% 3	5919
April	1st to 10th	Day	56% 9% 15% 14% 5% 1	2481
	11th to 20th	Day	48% 10% 12% 21% 8%	2631
	21st to end	Day	51% 8% 12% 21% 8%	2726
May	1st to 10th	Day	67% 10% 11% 10% 1	5070
	11th to 20th	Day	55% 11% 14% 17% 3	5077
	21st to end	Day	60% 12% 12% 14% 2	6171
June	1st to 10th	Day	59% 11% 16% 11% 2	3420
	11th to 20th	Day	62% 12% 14% 9% 4	3420
	21st to end	Day	63% 16% 16% 5%	3420
July	1st to 10th	Day	74% 9% 12% 4 1	5611
	11th to 20th	Day	71% 10% 15% 5%	5576
	21st to end	Day	60% 10% 19% 10%	5480
August	1st to 10th	Day	71% 9% 16% 3	5027
	11th to 20th	Day	65% 10% 13% 11% 1	4565
	21st to end	Day	64% 9% 17% 9% 2	4883
September	1st to 10th	Day	72% 10% 9% 7% 3	2379
	11th to 20th	Day	74% 8% 10% 7% 1	2280
	21st to end	Day	61% 10% 13% 13% 3	2018
October	1st to 10th	Day	55% 9% 16% 19% 2	3130
	11th to 20th	Day	45% 7% 16% 21% 11% 1	2750
	21st to end	Day	52% 6% 8% 27% 6% 1	2653
November	1st to 10th	Day	57% 7% 11% 15% 7% 3	1311
	11th to 20th	Day	46% 6% 9% 24% 14% 1	1169
	21st to end	Day	60% 8% 8% 8% 14% 3	960
December	1st to 10th	Day	66% 7% 6% 14% 6% 1	1310
	11th to 20th	Day	67% 6% 11% 11% 4 1	1520
	21st to end	Day	52% 5% 13% 13% 13% 4	2002
January	1st to 10th	Night	51% 7% 10% 13% 12% 7%	8146
	11th to 20th	Night	62% 6% 8% 11% 11% 2	7875
	21st to end	Night	51% 5% 7% 8% 20% 9%	8053
February	1st to 10th	Night	48% 4 9% 17% 16% 7%	3061
	11th to 20th	Night	65% 6% 8% 10% 9% 3	2773
	21st to end	Night	58% 6% 9% 13% 12% 2	2208
March	1st to 10th	Night	56% 5% 9% 11% 14% 5%	5498
	11th to 20th	Night	56% 7% 9% 13% 15% 1	5261
	21st to end	Night	54% 7% 9% 17% 11% 2	5012
April	1st to 10th	Night	62% 7% 12% 13% 5% 1	1916
	11th to 20th	Night	51% 10% 11% 19% 8% 1	1504
	21st to end	Night	52% 7% 14% 19% 8%	1451
May	1st to 10th	Night	69% 9% 10% 10% 1	1900
	11th to 20th	Night	58% 12% 13% 13% 4	1830
	21st to end	Night	59% 10% 13% 15% 2	1412
June	1st to 10th	Night	65% 11% 14% 9% 1	760
	11th to 20th	Night	60% 12% 14% 10% 4	760
	21st to end	Night	65% 13% 16% 6%	760
July	1st to 10th	Night	73% 10% 13% 4	1250
	11th to 20th	Night	69% 9% 16% 6%	1270
	21st to end	Night	64% 8% 21% 6%	1851
August	1st to 10th	Night	68% 9% 18% 4	1888
	11th to 20th	Night	63% 9% 16% 11% 1	2338
	21st to end	Night	71% 8% 12% 6% 2	2783
September	1st to 10th	Night	72% 8% 9% 8% 2	1800
	11th to 20th	Night	72% 8% 9% 10% 1	1900
	21st to end	Night	65% 8% 11% 13% 3	2159
October	1st to 10th	Night	62% 7% 12% 15% 3	3830
	11th to 20th	Night	48% 7% 14% 18% 12% 1	4178
	21st to end	Night	55% 7% 11% 19% 8%	4906
November	1st to 10th	Night	58% 7% 12% 14% 7% 2	2984
	11th to 20th	Night	47% 6% 11% 24% 12%	3231
	21st to end	Night	58% 6% 9% 10% 13% 3	3435
December	1st to 10th	Night	67% 5% 7% 13% 7%	5880
	11th to 20th	Night	67% 6% 12% 10% 4	6696
	21st to end	Night	53% 5% 13% 13% 11% 4	8976

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	16% 10% 25% 33% 14% 2	100
	11th to 20th	Day	20% 15% 27% 23% 12% 4	225
	21st to end	Day	26% 14% 24% 23% 12% 2	330
February	1st to 10th	Day	14% 11% 25% 24% 17% 9%	300
	11th to 20th	Day	23% 13% 24% 23% 15% 3	375
	21st to end	Day	17% 10% 27% 25% 14% 7%	331
March	1st to 10th	Day	17% 12% 27% 24% 17% 5%	400
	11th to 20th	Day	14% 8% 21% 31% 19% 7%	473
	21st to end	Day	14% 9% 22% 24% 21% 10%	660
April	1st to 10th	Day	15% 9% 25% 27% 16% 7%	617
	11th to 20th	Day	14% 7% 17% 28% 24% 10%	642
	21st to end	Day	14% 4 16% 32% 28% 6%	650
May	1st to 10th	Day	16% 7% 21% 26% 25% 5%	653
	11th to 20th	Day	17% 8% 20% 29% 20% 6%	675
	21st to end	Day	22% 6% 23% 27% 18% 3	918
June	1st to 10th	Day	23% 6% 16% 25% 25% 5%	870
	11th to 20th	Day	21% 6% 17% 26% 23% 7%	870
	21st to end	Day	21% 5% 14% 21% 28% 12%	870
July	1st to 10th	Day	24% 6% 13% 25% 23% 9%	856
	11th to 20th	Day	28% 5% 16% 25% 20% 7%	852
	21st to end	Day	29% 3 15% 21% 22% 10%	833
August	1st to 10th	Day	35% 7% 15% 21% 16% 7%	676
	11th to 20th	Day	32% 8% 17% 21% 16% 6%	665
	21st to end	Day	35% 5% 14% 18% 19% 8%	748
September	1st to 10th	Day	37% 5% 16% 17% 18% 7%	604
	11th to 20th	Day	40% 7% 11% 17% 16% 10%	580
	21st to end	Day	29% 8% 15% 21% 18% 10%	406
October	1st to 10th	Day	32% 6% 16% 22% 15% 8%	390
	11th to 20th	Day	26% 8% 19% 22% 18% 7%	390
	21st to end	Day	28% 7% 22% 26% 14% 3	429
November	1st to 10th	Day	24% 7% 25% 24% 16% 4	365
	11th to 20th	Day	17% 10% 22% 29% 16% 6%	269
	21st to end	Day	18% 14% 21% 31% 12% 4	100
December	1st to 10th	Day	23% 12% 22% 36% 7%	100
	11th to 20th	Day	19% 12% 30% 28% 8% 3	100
	21st to end	Day	28% 12% 23% 23% 12% 3	110
January	1st to 10th	Night	15% 11% 25% 30% 16% 3	1000
	11th to 20th	Night	21% 13% 26% 27% 11% 2	1000
	21st to end	Night	26% 9% 31% 25% 9%	1003
February	1st to 10th	Night	16% 12% 26% 26% 17% 2	900
	11th to 20th	Night	25% 12% 28% 26% 9% 1	884
	21st to end	Night	16% 9% 28% 32% 13% 2	641
March	1st to 10th	Night	16% 11% 30% 27% 14% 2	700
	11th to 20th	Night	12% 6% 29% 33% 16% 2	700
	21st to end	Night	17% 6% 22% 25% 23% 6%	671
April	1st to 10th	Night	19% 8% 24% 26% 19% 5%	600
	11th to 20th	Night	13% 6% 21% 30% 24% 6%	564
	21st to end	Night	16% 4 13% 30% 32% 5%	553
May	1st to 10th	Night	16% 7% 16% 27% 30% 5%	380
	11th to 20th	Night	15% 5% 23% 32% 23% 2	347
	21st to end	Night	23% 6% 19% 29% 20% 1	206
June	1st to 10th	Night	24% 6% 19% 27% 24% 1	190
	11th to 20th	Night	23% 3 12% 37% 24% 1	190
	21st to end	Night	26% 7% 13% 27% 25% 2	190
July	1st to 10th	Night	24% 4 18% 32% 19% 2	185
	11th to 20th	Night	33% 5% 17% 26% 18% 1	195
	21st to end	Night	31% 5% 16% 23% 22% 4	416
August	1st to 10th	Night	39% 4 17% 21% 17% 3	378
	11th to 20th	Night	39% 6% 12% 24% 17% 2	472
	21st to end	Night	37% 4 12% 23% 19% 5%	627
September	1st to 10th	Night	38% 5% 14% 21% 19% 3	570
	11th to 20th	Night	41% 6% 11% 19% 19% 4	570
	21st to end	Night	32% 5% 17% 26% 15% 5%	615
October	1st to 10th	Night	39% 6% 17% 18% 15% 5%	687
	11th to 20th	Night	28% 6% 22% 24% 17% 3	860
	21st to end	Night	25% 7% 23% 27% 15% 2	946
November	1st to 10th	Night	25% 9% 26% 25% 14% 1	880
	11th to 20th	Night	21% 7% 28% 30% 13% 1	900
	21st to end	Night	24% 11% 23% 26% 14% 3	917
December	1st to 10th	Night	30% 8% 26% 23% 10% 2	1000
	11th to 20th	Night	21% 11% 28% 25% 11% 4	1000
	21st to end	Night	24% 11% 25% 25% 13% 2	1100

Page generated at 2025-04-08 05:17:24. Version ac07

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