Klickitat County Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Klickitat County Star Party clear sky chart from 2005-11-06 to 2024-11-05.

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	7% 7% 3 6% 4 4 4 4 5% 7% 49%	105357
	Night	9% 8% 3 6% 5% 4 4 4 5% 7% 46%	102368
Transparency	Day	34% 7% 12% 21% 17% 8%	105100
	Night	38% 8% 13% 22% 14% 6%	102214
Seeing	Day	14% 18% 29% 24% 12% 3	14493
	Night	14% 13% 25% 29% 17% 3	23489

By Month

Percentage Cloud Cover SW (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	15% 22% 7% 14% 7% 5% 5% 3 5% 5% 13%	2539
	11th to 20th	Day	18% 17% 6% 11% 5% 5% 4 4 5% 8% 18%	2540
	21st to end	Day	24% 13% 5% 11% 7% 5% 5% 5% 6% 6% 14%	2837
February	1st to 10th	Day	13% 15% 5% 9% 6% 5% 4 5% 5% 7% 27%	1710
	11th to 20th	Day	12% 11% 3 9% 7% 4 5% 4 6% 7% 32%	1669
	21st to end	Day	7% 11% 5% 10% 8% 8% 5% 5% 6% 7% 28%	1570
March	1st to 10th	Day	7% 9% 3 9% 5% 5% 6% 5% 8% 11% 32%	3138
	11th to 20th	Day	6% 8% 3 6% 4 4 4 4 5% 8% 48%	3449
	21st to end	Day	8% 11% 4 10% 7% 6% 6% 5% 7% 8% 27%	4041
April	1st to 10th	Day	8% 10% 3 8% 6% 6% 7% 5% 7% 8% 33%	2280
	11th to 20th	Day	7% 10% 3 8% 5% 5% 6% 4 6% 8% 40%	2249
	21st to end	Day	5% 7% 3 6% 5% 5% 6% 4 7% 8% 44%	2423
May	1st to 10th	Day	10% 6% 2 5% 4 4 4 3 6% 8% 49%	4420
	11th to 20th	Day	4 4 2 4 3 3 4 3 5% 8% 60%	4377
	21st to end	Day	6% 6% 2 6% 6% 5% 6% 5% 7% 8% 43%	4813
June	1st to 10th	Day	9% 5% 2 5% 3 4 5% 5% 6% 8% 47%	2660
	11th to 20th	Day	5% 4 1 4 4 4 5% 4 5% 8% 55%	2660
	21st to end	Day	3 3 1 3 2 2 3 3 5% 6% 68%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 3 4 85%	4420
	11th to 20th	Day	2 1 1 1 1 2 2 2 3 83%	4420
	21st to end	Day	1 2 1 2 1 2 2 2 3 4 81%	4790
August	1st to 10th	Day	3 3 1 3 2 2 2 2 4 5% 73%	4376
	11th to 20th	Day	2 2 1 3 2 3 3 2 4 6% 72%	4009
	21st to end	Day	4 5% 1 4 3 3 3 3 3 4 67%	4180
September	1st to 10th	Day	3 2 1 2 2 2 3 2 4 6% 74%	2280
	11th to 20th	Day	4 4 2 5% 4 4 4 4 5% 6% 59%	2280
	21st to end	Day	6% 5% 2 5% 3 4 3 3 4 7% 57%	2044
October	1st to 10th	Day	5% 4 2 4 3 3 3 3 7% 7% 59%	3180
	11th to 20th	Day	6% 7% 3 7% 5% 5% 5% 4 7% 8% 43%	3161
	21st to end	Day	10% 7% 3 8% 6% 5% 5% 4 7% 8% 36%	3195
November	1st to 10th	Day	11% 12% 4 9% 6% 5% 5% 5% 6% 9% 29%	1705
	11th to 20th	Day	12% 11% 6% 10% 8% 6% 5% 5% 7% 8% 23%	1520
	21st to end	Day	10% 13% 3 10% 6% 5% 5% 4 7% 7% 29%	1520
December	1st to 10th	Day	12% 13% 5% 10% 7% 5% 5% 4 6% 6% 28%	1520
	11th to 20th	Day	14% 17% 6% 13% 9% 7% 7% 4 6% 6% 13%	1928
	21st to end	Day	15% 17% 6% 14% 7% 6% 5% 3 4 5% 18%	2794
January	1st to 10th	Night	16% 16% 5% 11% 7% 5% 6% 5% 6% 5% 18%	4406
	11th to 20th	Night	19% 14% 5% 10% 5% 4 5% 4 4 6% 23%	4420
	21st to end	Night	21% 12% 4 9% 6% 5% 5% 4 6% 7% 18%	4817
February	1st to 10th	Night	11% 14% 4 10% 7% 5% 4 4 5% 7% 29%	2470
	11th to 20th	Night	11% 11% 4 8% 6% 5% 4 4 5% 6% 36%	2398
	21st to end	Night	9% 14% 5% 8% 6% 4 5% 5% 6% 7% 32%	1884
March	1st to 10th	Night	7% 9% 3 8% 6% 5% 5% 5% 7% 9% 35%	3736
	11th to 20th	Night	6% 6% 2 5% 4 4 3 4 5% 7% 53%	3530
	21st to end	Night	8% 9% 4 8% 6% 6% 6% 5% 7% 9% 32%	3612
April	1st to 10th	Night	8% 9% 3 8% 4 5% 4 4 8% 9% 37%	1900
	11th to 20th	Night	8% 7% 2 5% 6% 4 4 3 5% 7% 49%	1879
	21st to end	Night	5% 6% 3 7% 5% 4 5% 4 7% 9% 45%	1751
May	1st to 10th	Night	8% 9% 3 5% 3 4 3 3 4 5% 54%	2540
	11th to 20th	Night	4 3 1 2 2 2 3 3 5% 8% 66%	2516
	21st to end	Night	4 6% 2 4 2 3 3 4 6% 8% 57%	2762
June	1st to 10th	Night	10% 5% 2 4 4 4 3 4 7% 7% 49%	1520
	11th to 20th	Night	7% 5% 2 3 4 2 4 3 5% 7% 60%	1520
	21st to end	Night	3 3 1 5% 3 3 3 3 5% 4 68%	1520
July	1st to 10th	Night	1 1 2 1 1 1 1 2 3 86%	2540
	11th to 20th	Night	1 1 1 2 2 1 1 2 3 4 82%	2540
	21st to end	Night	1 1 1 1 1 2 1 3 4 84%	2761
August	1st to 10th	Night	3 3 1 3 2 2 2 2 4 6% 72%	2551
	11th to 20th	Night	2 2 1 2 2 3 3 3 5% 6% 73%	2830
	21st to end	Night	2 4 1 3 3 2 3 3 4 5% 71%	3498
September	1st to 10th	Night	2 1 1 2 2 2 3 2 5% 5% 74%	1900
	11th to 20th	Night	4 4 1 4 4 4 4 3 4 5% 62%	1900
	21st to end	Night	6% 3 2 4 3 3 3 3 5% 7% 60%	2133
October	1st to 10th	Night	4 3 2 4 3 3 3 3 5% 6% 63%	3800
	11th to 20th	Night	6% 5% 2 7% 5% 4 5% 4 7% 8% 45%	3777
	21st to end	Night	9% 6% 2 6% 4 5% 5% 5% 7% 8% 42%	4366
November	1st to 10th	Night	14% 10% 3 8% 5% 4 4 4 6% 7% 35%	2473
	11th to 20th	Night	14% 12% 4 7% 6% 5% 6% 4 6% 7% 29%	2660
	21st to end	Night	10% 9% 3 8% 7% 5% 5% 4 7% 7% 34%	2660
December	1st to 10th	Night	13% 12% 4 10% 8% 5% 5% 4 5% 6% 28%	2660
	11th to 20th	Night	16% 14% 5% 11% 8% 7% 5% 4 6% 7% 16%	3276
	21st to end	Night	14% 13% 5% 12% 6% 5% 4 4 4 7% 25%	4862

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	68% 9% 12% 9% 1	2539
	11th to 20th	Day	63% 11% 16% 8% 1	2540
	21st to end	Day	68% 12% 12% 6% 2	2837
February	1st to 10th	Day	57% 10% 16% 14% 3	1710
	11th to 20th	Day	50% 12% 15% 17% 6%	1678
	21st to end	Day	51% 10% 18% 13% 7% 1	1570
March	1st to 10th	Day	42% 8% 17% 23% 10% 1	3138
	11th to 20th	Day	34% 7% 15% 33% 10%	3449
	21st to end	Day	50% 10% 16% 17% 7%	4041
April	1st to 10th	Day	45% 9% 16% 19% 10%	2280
	11th to 20th	Day	41% 8% 16% 19% 13% 3	2252
	21st to end	Day	34% 10% 15% 25% 14% 2	2423
May	1st to 10th	Day	32% 5% 14% 24% 24% 2	4420
	11th to 20th	Day	22% 5% 12% 34% 22% 5%	4380
	21st to end	Day	33% 10% 24% 25% 8% 1	4814
June	1st to 10th	Day	34% 8% 12% 28% 15% 3	2660
	11th to 20th	Day	26% 6% 15% 32% 18% 3	2660
	21st to end	Day	18% 5% 11% 32% 24% 9%	2660
July	1st to 10th	Day	6% 2 5% 15% 29% 41%	4351
	11th to 20th	Day	9% 2 5% 10% 25% 50%	4345
	21st to end	Day	10% 1 6% 18% 40% 24%	4639
August	1st to 10th	Day	16% 2 5% 14% 36% 26%	4360
	11th to 20th	Day	15% 2 7% 40% 27% 8%	4048
	21st to end	Day	22% 2 9% 25% 35% 7%	4179
September	1st to 10th	Day	14% 4 8% 30% 30% 13%	2280
	11th to 20th	Day	25% 6% 12% 27% 23% 8%	2280
	21st to end	Day	29% 5% 15% 28% 18% 5%	2044
October	1st to 10th	Day	25% 5% 10% 31% 26% 3	3180
	11th to 20th	Day	39% 6% 16% 23% 16% 1	3161
	21st to end	Day	45% 5% 10% 27% 11% 1	3195
November	1st to 10th	Day	53% 9% 14% 17% 6% 1	1705
	11th to 20th	Day	58% 12% 16% 11% 3 1	1520
	21st to end	Day	52% 11% 15% 13% 8% 1	1520
December	1st to 10th	Day	56% 8% 16% 14% 5%	1520
	11th to 20th	Day	67% 15% 10% 6% 2	1928
	21st to end	Day	66% 11% 12% 9% 2	2794
January	1st to 10th	Night	63% 14% 12% 9% 2	4406
	11th to 20th	Night	59% 10% 18% 10% 3	4420
	21st to end	Night	65% 13% 12% 8% 2	4817
February	1st to 10th	Night	54% 10% 18% 15% 3	2470
	11th to 20th	Night	48% 9% 15% 19% 8% 1	2400
	21st to end	Night	48% 11% 16% 17% 7% 1	1884
March	1st to 10th	Night	40% 8% 19% 26% 7% 1	3736
	11th to 20th	Night	31% 8% 17% 31% 12% 1	3530
	21st to end	Night	43% 13% 20% 21% 3	3612
April	1st to 10th	Night	40% 11% 17% 21% 10% 1	1900
	11th to 20th	Night	34% 7% 17% 26% 13% 3	1879
	21st to end	Night	34% 10% 16% 25% 13% 2	1751
May	1st to 10th	Night	31% 4 12% 27% 24% 2	2540
	11th to 20th	Night	17% 5% 13% 37% 25% 3	2516
	21st to end	Night	22% 8% 32% 30% 7% 1	2762
June	1st to 10th	Night	33% 9% 11% 31% 12% 4	1520
	11th to 20th	Night	25% 5% 15% 35% 20% 1	1520
	21st to end	Night	20% 4 11% 33% 26% 7%	1520
July	1st to 10th	Night	8% 2 6% 14% 33% 37%	2500
	11th to 20th	Night	9% 2 5% 12% 25% 47%	2492
	21st to end	Night	8% 1 6% 18% 38% 31%	2674
August	1st to 10th	Night	15% 1 4 15% 38% 26%	2543
	11th to 20th	Night	15% 1 6% 43% 26% 8%	2857
	21st to end	Night	18% 2 10% 29% 32% 11%	3498
September	1st to 10th	Night	12% 4 11% 27% 31% 16%	1900
	11th to 20th	Night	24% 6% 9% 30% 21% 11%	1900
	21st to end	Night	23% 7% 13% 29% 21% 8%	2133
October	1st to 10th	Night	22% 4 9% 31% 32% 2	3800
	11th to 20th	Night	37% 4 14% 27% 17% 1	3777
	21st to end	Night	40% 5% 9% 30% 14% 1	4366
November	1st to 10th	Night	47% 9% 14% 20% 9%	2473
	11th to 20th	Night	53% 11% 14% 17% 5%	2660
	21st to end	Night	47% 13% 14% 18% 8%	2660
December	1st to 10th	Night	56% 9% 16% 15% 3	2660
	11th to 20th	Night	63% 13% 14% 8% 2	3276
	21st to end	Night	57% 14% 12% 11% 6%	4862

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	26% 24% 23% 16% 8% 3	180
	11th to 20th	Day	26% 18% 24% 22% 9% 1	180
	21st to end	Day	22% 19% 28% 19% 11% 1	228
February	1st to 10th	Day	28% 16% 30% 19% 6% 1	370
	11th to 20th	Day	28% 20% 28% 19% 4 1	367
	21st to end	Day	20% 27% 26% 19% 7% 1	382
March	1st to 10th	Day	20% 23% 32% 18% 6% 1	460
	11th to 20th	Day	20% 21% 29% 21% 9% 1	460
	21st to end	Day	21% 26% 28% 17% 7%	506
April	1st to 10th	Day	22% 21% 32% 15% 7% 2	460
	11th to 20th	Day	19% 28% 28% 15% 8% 2	452
	21st to end	Day	15% 27% 32% 18% 6% 2	460
May	1st to 10th	Day	13% 19% 33% 23% 10% 2	463
	11th to 20th	Day	17% 17% 29% 21% 12% 3	488
	21st to end	Day	11% 18% 28% 28% 12% 4	529
June	1st to 10th	Day	13% 22% 24% 26% 12% 3	490
	11th to 20th	Day	11% 25% 34% 20% 7% 2	490
	21st to end	Day	7% 18% 26% 32% 14% 4	490
July	1st to 10th	Day	3 11% 37% 32% 15% 2	486
	11th to 20th	Day	3 12% 34% 32% 16% 2	484
	21st to end	Day	2 8% 31% 33% 21% 5%	531
August	1st to 10th	Day	5% 8% 27% 29% 21% 9%	487
	11th to 20th	Day	2 8% 24% 32% 27% 7%	477
	21st to end	Day	9% 12% 30% 26% 17% 6%	539
September	1st to 10th	Day	6% 10% 30% 31% 15% 8%	490
	11th to 20th	Day	9% 10% 31% 31% 16% 3	490
	21st to end	Day	9% 18% 27% 27% 17% 2	490
October	1st to 10th	Day	13% 17% 28% 23% 16% 3	490
	11th to 20th	Day	18% 17% 23% 24% 14% 4	490
	21st to end	Day	19% 21% 25% 18% 14% 3	387
November	1st to 10th	Day	21% 19% 28% 23% 9%	279
	11th to 20th	Day	21% 25% 18% 24% 9% 3	180
	21st to end	Day	18% 21% 27% 20% 12% 2	180
December	1st to 10th	Day	23% 18% 28% 15% 10% 7%	180
	11th to 20th	Day	24% 23% 27% 19% 6% 1	180
	21st to end	Day	21% 25% 24% 19% 11% 1	198
January	1st to 10th	Night	25% 16% 22% 28% 8% 1	760
	11th to 20th	Night	22% 11% 25% 24% 16% 3	760
	21st to end	Night	22% 10% 20% 29% 16% 2	836
February	1st to 10th	Night	20% 17% 25% 24% 13% 2	760
	11th to 20th	Night	18% 18% 23% 28% 12% 1	744
	21st to end	Night	19% 19% 26% 25% 10% 1	628
March	1st to 10th	Night	16% 15% 29% 23% 16% 2	760
	11th to 20th	Night	13% 16% 27% 30% 12% 2	760
	21st to end	Night	14% 22% 31% 21% 10% 2	836
April	1st to 10th	Night	17% 17% 28% 24% 12% 3	760
	11th to 20th	Night	15% 20% 29% 20% 13% 3	751
	21st to end	Night	11% 19% 30% 25% 13% 2	611
May	1st to 10th	Night	9% 17% 26% 29% 16% 3	380
	11th to 20th	Night	13% 7% 25% 32% 20% 2	374
	21st to end	Night	9% 7% 31% 33% 17% 4	411
June	1st to 10th	Night	14% 13% 25% 29% 16% 2	380
	11th to 20th	Night	11% 16% 31% 29% 12% 1	380
	21st to end	Night	6% 11% 23% 38% 21% 2	380
July	1st to 10th	Night	4 5% 26% 42% 22% 2	370
	11th to 20th	Night	2 6% 33% 40% 16% 3	368
	21st to end	Night	2 8% 18% 44% 26% 3	416
August	1st to 10th	Night	3 5% 16% 44% 27% 5%	387
	11th to 20th	Night	5% 3 17% 32% 30% 13%	569
	21st to end	Night	4 10% 26% 32% 23% 6%	836
September	1st to 10th	Night	3 7% 22% 36% 28% 4	760
	11th to 20th	Night	6% 7% 23% 29% 28% 8%	760
	21st to end	Night	8% 11% 20% 28% 28% 5%	760
October	1st to 10th	Night	10% 9% 24% 33% 20% 3	760
	11th to 20th	Night	14% 12% 21% 28% 21% 4	760
	21st to end	Night	16% 15% 24% 27% 15% 4	836
November	1st to 10th	Night	20% 13% 25% 30% 12%	760
	11th to 20th	Night	23% 14% 24% 24% 13% 2	760
	21st to end	Night	14% 15% 23% 28% 16% 3	760
December	1st to 10th	Night	18% 13% 26% 26% 15% 2	760
	11th to 20th	Night	24% 11% 24% 27% 11% 2	760
	21st to end	Night	22% 17% 27% 24% 9% 1	836

Page generated at 2024-11-02 23:11:19. Version ac07

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