Kalama
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kalama clear sky chart from 2005-11-06 to 2024-11-12.

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	18% 10% 3 8% 5% 4 4 4 5% 6% 33%	105958
	Night	19% 11% 3 8% 5% 4 4 3 4 5% 33%	101848
Transparency	Day	28% 46% 6% 10% 7% 2	105722
	Night	30% 46% 6% 10% 6% 1	101730
Seeing	Day	25% 12% 26% 25% 10% 2	14999
	Night	29% 6% 17% 31% 15% 1	23520

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	34% 19% 5% 9% 5% 4 4 3 4 3 8%	2539
	11th to 20th	Day	34% 14% 4 9% 4 4 3 3 2 4 19%	2516
	21st to end	Day	32% 16% 5% 11% 6% 4 4 3 4 3 12%	3022
February	1st to 10th	Day	31% 15% 4 8% 5% 5% 4 4 5% 6% 14%	1710
	11th to 20th	Day	30% 15% 6% 9% 6% 4 4 3 3 4 16%	1665
	21st to end	Day	29% 17% 5% 9% 4 5% 3 3 4 4 15%	1475
March	1st to 10th	Day	19% 17% 6% 13% 7% 6% 5% 3 5% 5% 14%	3287
	11th to 20th	Day	21% 11% 4 8% 5% 4 3 3 4 5% 32%	3490
	21st to end	Day	24% 16% 5% 12% 6% 5% 5% 4 5% 4 14%	3907
April	1st to 10th	Day	28% 15% 5% 10% 5% 5% 4 3 5% 5% 15%	2280
	11th to 20th	Day	25% 14% 4 9% 5% 4 4 4 5% 4 22%	2265
	21st to end	Day	23% 12% 4 9% 7% 5% 5% 4 5% 5% 21%	2470
May	1st to 10th	Day	21% 9% 3 8% 5% 4 4 3 4 5% 34%	4378
	11th to 20th	Day	12% 7% 3 7% 5% 5% 5% 5% 7% 8% 36%	4377
	21st to end	Day	22% 10% 3 10% 7% 6% 6% 5% 5% 6% 21%	4813
June	1st to 10th	Day	22% 10% 4 8% 5% 4 4 4 5% 6% 29%	2660
	11th to 20th	Day	19% 10% 3 9% 6% 6% 6% 4 6% 7% 23%	2739
	21st to end	Day	10% 7% 3 6% 5% 5% 5% 4 6% 7% 43%	2850
July	1st to 10th	Day	5% 4 2 5% 4 3 3 2 3 5% 66%	4622
	11th to 20th	Day	5% 3 1 3 2 2 3 2 4 6% 68%	4420
	21st to end	Day	8% 3 1 4 3 3 3 3 5% 6% 61%	4790
August	1st to 10th	Day	4 4 2 4 3 3 3 3 5% 7% 62%	4162
	11th to 20th	Day	6% 5% 2 7% 6% 5% 6% 6% 7% 9% 42%	4026
	21st to end	Day	11% 8% 3 6% 4 3 4 3 5% 6% 46%	4318
September	1st to 10th	Day	8% 6% 2 5% 4 3 4 3 6% 7% 52%	2280
	11th to 20th	Day	12% 7% 3 9% 5% 5% 5% 3 5% 7% 38%	2280
	21st to end	Day	17% 7% 2 6% 5% 4 4 3 5% 6% 40%	1998
October	1st to 10th	Day	16% 7% 2 6% 3 3 5% 3 6% 9% 41%	3180
	11th to 20th	Day	19% 9% 4 10% 6% 5% 5% 4 6% 7% 26%	3161
	21st to end	Day	24% 11% 4 9% 6% 5% 5% 4 6% 6% 21%	3359
November	1st to 10th	Day	29% 13% 5% 10% 5% 5% 6% 4 5% 5% 13%	1632
	11th to 20th	Day	34% 13% 3 8% 4 4 4 3 5% 5% 17%	1528
	21st to end	Day	30% 13% 5% 9% 5% 3 4 3 5% 4 20%	1520
December	1st to 10th	Day	25% 15% 4 9% 5% 5% 5% 3 4 4 20%	1520
	11th to 20th	Day	27% 12% 5% 12% 7% 5% 4 4 5% 4 14%	1925
	21st to end	Day	28% 17% 5% 11% 8% 5% 4 4 4 4 11%	2794
January	1st to 10th	Night	33% 16% 5% 11% 6% 5% 5% 3 3 3 11%	4406
	11th to 20th	Night	30% 15% 4 10% 5% 4 4 2 4 4 18%	4382
	21st to end	Night	34% 16% 5% 9% 5% 4 4 2 3 4 13%	4636
February	1st to 10th	Night	27% 16% 4 10% 6% 4 4 4 4 4 16%	2470
	11th to 20th	Night	24% 16% 4 9% 5% 4 4 3 4 5% 22%	2402
	21st to end	Night	26% 15% 4 10% 5% 5% 3 4 4 4 19%	1978
March	1st to 10th	Night	17% 19% 5% 11% 6% 6% 6% 4 5% 4 18%	3585
	11th to 20th	Night	18% 12% 3 6% 4 4 5% 3 5% 5% 34%	3489
	21st to end	Night	26% 18% 5% 11% 5% 5% 4 3 4 4 14%	3746
April	1st to 10th	Night	24% 15% 4 10% 6% 5% 3 3 4 5% 22%	1900
	11th to 20th	Night	19% 12% 4 8% 6% 5% 4 3 5% 6% 27%	1862
	21st to end	Night	22% 12% 4 8% 4 4 4 4 5% 7% 27%	1710
May	1st to 10th	Night	20% 10% 3 7% 4 3 4 3 3 5% 39%	2582
	11th to 20th	Night	9% 5% 3 5% 4 4 4 4 5% 7% 50%	2516
	21st to end	Night	10% 10% 3 8% 7% 5% 5% 5% 6% 7% 33%	2762
June	1st to 10th	Night	16% 9% 3 8% 5% 4 4 3 4 6% 37%	1520
	11th to 20th	Night	14% 8% 2 6% 5% 4 4 3 5% 9% 39%	1435
	21st to end	Night	9% 5% 2 5% 3 3 3 3 4 7% 57%	1330
July	1st to 10th	Night	2 2 1 2 2 2 2 2 3 5% 76%	2334
	11th to 20th	Night	3 3 1 3 3 2 2 2 3 4 74%	2540
	21st to end	Night	3 2 1 2 2 2 2 2 4 6% 74%	2762
August	1st to 10th	Night	2 1 1 3 2 2 2 2 4 6% 74%	2774
	11th to 20th	Night	6% 3 2 4 3 3 4 4 6% 9% 57%	2812
	21st to end	Night	11% 5% 2 5% 4 3 3 3 4 5% 55%	3355
September	1st to 10th	Night	7% 3 1 4 3 3 4 3 4 5% 63%	1900
	11th to 20th	Night	10% 7% 3 7% 5% 4 4 3 5% 6% 46%	1900
	21st to end	Night	11% 6% 2 6% 5% 4 4 3 5% 8% 47%	2178
October	1st to 10th	Night	12% 6% 1 5% 4 4 5% 4 6% 8% 46%	3800
	11th to 20th	Night	18% 8% 3 8% 4 4 5% 4 6% 8% 32%	3777
	21st to end	Night	22% 10% 4 8% 6% 5% 5% 4 5% 6% 25%	4206
November	1st to 10th	Night	29% 11% 4 9% 5% 4 5% 3 4 4 20%	2663
	11th to 20th	Night	32% 11% 3 8% 5% 4 4 3 4 4 20%	2674
	21st to end	Night	27% 13% 3 8% 5% 4 5% 3 4 5% 24%	2660
December	1st to 10th	Night	26% 13% 4 7% 5% 4 5% 4 5% 5% 22%	2660
	11th to 20th	Night	27% 14% 5% 10% 6% 6% 4 3 4 5% 16%	3280
	21st to end	Night	27% 16% 5% 11% 6% 6% 6% 4 4 4 12%	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	53% 36% 5% 3 2 1	2539
	11th to 20th	Day	47% 36% 4 10% 3	2540
	21st to end	Day	53% 39% 3 4 1	3022
February	1st to 10th	Day	29% 64% 3 3 1	1710
	11th to 20th	Day	30% 64% 1 3 1	1674
	21st to end	Day	27% 64% 3 3 3	1475
March	1st to 10th	Day	43% 40% 8% 6% 3	3287
	11th to 20th	Day	27% 41% 6% 23% 4	3490
	21st to end	Day	43% 40% 8% 7% 2	3907
April	1st to 10th	Day	26% 65% 5% 4 1	2280
	11th to 20th	Day	23% 65% 3 5% 4	2265
	21st to end	Day	24% 64% 4 6% 3	2470
May	1st to 10th	Day	31% 40% 7% 14% 7%	4378
	11th to 20th	Day	26% 40% 17% 14% 3	4380
	21st to end	Day	41% 41% 12% 6% 1	4814
June	1st to 10th	Day	16% 65% 8% 8% 3	2660
	11th to 20th	Day	19% 64% 5% 8% 3	2739
	21st to end	Day	15% 63% 6% 12% 4	2850
July	1st to 10th	Day	12% 35% 3 10% 14% 25%	4551
	11th to 20th	Day	8% 35% 4 13% 31% 8%	4345
	21st to end	Day	18% 35% 8% 20% 18% 2	4639
August	1st to 10th	Day	14% 36% 4 16% 22% 7%	4145
	11th to 20th	Day	26% 41% 13% 14% 4 2	4065
	21st to end	Day	25% 37% 7% 14% 13% 3	4317
September	1st to 10th	Day	15% 60% 5% 11% 6% 2	2280
	11th to 20th	Day	20% 60% 5% 6% 6% 2	2280
	21st to end	Day	18% 60% 6% 9% 7% 1	1998
October	1st to 10th	Day	22% 36% 5% 22% 15%	3180
	11th to 20th	Day	38% 38% 7% 9% 7%	3161
	21st to end	Day	42% 37% 6% 9% 5%	3359
November	1st to 10th	Day	32% 56% 4 7% 1	1632
	11th to 20th	Day	27% 60% 4 4 4 1	1528
	21st to end	Day	24% 59% 2 5% 9%	1520
December	1st to 10th	Day	29% 60% 2 4 4 1	1520
	11th to 20th	Day	38% 47% 6% 8% 1	1928
	21st to end	Day	50% 37% 7% 5% 1	2794
January	1st to 10th	Night	54% 36% 4 3 2 1	4406
	11th to 20th	Night	46% 38% 3 11% 2	4420
	21st to end	Night	52% 38% 4 4 1	4636
February	1st to 10th	Night	29% 65% 2 4 1	2470
	11th to 20th	Night	28% 64% 2 4 2	2404
	21st to end	Night	24% 65% 4 5% 3	1978
March	1st to 10th	Night	43% 41% 4 9% 2	3585
	11th to 20th	Night	25% 41% 9% 19% 5% 1	3490
	21st to end	Night	46% 40% 6% 7%	3746
April	1st to 10th	Night	23% 65% 6% 5% 1	1900
	11th to 20th	Night	20% 65% 5% 6% 4	1862
	21st to end	Night	21% 64% 5% 7% 2	1710
May	1st to 10th	Night	30% 40% 8% 14% 7%	2582
	11th to 20th	Night	18% 39% 17% 18% 7%	2516
	21st to end	Night	31% 44% 17% 7% 1	2762
June	1st to 10th	Night	16% 64% 7% 10% 3	1520
	11th to 20th	Night	14% 65% 6% 12% 4	1435
	21st to end	Night	11% 63% 8% 14% 3 1	1330
July	1st to 10th	Night	7% 35% 4 16% 14% 25%	2296
	11th to 20th	Night	9% 35% 3 16% 29% 8%	2492
	21st to end	Night	12% 36% 8% 23% 20% 2	2674
August	1st to 10th	Night	9% 36% 5% 22% 25% 4	2766
	11th to 20th	Night	23% 42% 16% 13% 4 2	2839
	21st to end	Night	22% 37% 11% 14% 15% 1	3355
September	1st to 10th	Night	13% 59% 7% 13% 6% 3	1900
	11th to 20th	Night	19% 60% 5% 8% 4 3	1900
	21st to end	Night	16% 60% 6% 11% 7%	2178
October	1st to 10th	Night	21% 38% 6% 22% 13%	3800
	11th to 20th	Night	34% 38% 8% 13% 7%	3777
	21st to end	Night	42% 38% 4 12% 4 1	4206
November	1st to 10th	Night	32% 55% 3 7% 2	2663
	11th to 20th	Night	27% 59% 4 5% 3 2	2674
	21st to end	Night	24% 59% 2 5% 9% 1	2660
December	1st to 10th	Night	28% 59% 3 6% 4 1	2660
	11th to 20th	Night	38% 49% 5% 6% 3	3276
	21st to end	Night	50% 37% 5% 6% 1	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	46% 11% 23% 12% 7% 3	180
	11th to 20th	Day	42% 16% 20% 13% 4 4	180
	21st to end	Day	39% 10% 21% 21% 9% 1	335
February	1st to 10th	Day	44% 10% 19% 16% 8% 2	370
	11th to 20th	Day	42% 14% 22% 16% 5% 1	365
	21st to end	Day	39% 15% 24% 15% 7%	337
March	1st to 10th	Day	35% 16% 26% 17% 6%	460
	11th to 20th	Day	33% 13% 23% 18% 9% 3	460
	21st to end	Day	36% 17% 23% 16% 7% 1	506
April	1st to 10th	Day	36% 15% 21% 19% 8% 2	460
	11th to 20th	Day	31% 23% 24% 14% 6% 2	452
	21st to end	Day	29% 16% 28% 20% 7% 1	460
May	1st to 10th	Day	21% 17% 28% 22% 10% 2	463
	11th to 20th	Day	28% 13% 23% 24% 10% 2	488
	21st to end	Day	25% 11% 26% 26% 10% 2	529
June	1st to 10th	Day	27% 10% 25% 28% 10% 1	490
	11th to 20th	Day	22% 17% 34% 20% 5% 1	569
	21st to end	Day	13% 9% 35% 32% 10% 1	680
July	1st to 10th	Day	11% 7% 34% 35% 11% 2	608
	11th to 20th	Day	9% 8% 29% 37% 14% 3	484
	21st to end	Day	7% 5% 31% 38% 17% 2	531
August	1st to 10th	Day	10% 5% 25% 44% 13% 3	487
	11th to 20th	Day	6% 5% 25% 40% 21% 5%	477
	21st to end	Day	11% 9% 35% 31% 12% 3	539
September	1st to 10th	Day	13% 6% 31% 35% 13% 2	490
	11th to 20th	Day	18% 9% 23% 32% 15% 2	490
	21st to end	Day	21% 12% 24% 30% 11% 2	490
October	1st to 10th	Day	27% 10% 24% 25% 12% 2	490
	11th to 20th	Day	29% 10% 21% 23% 15% 2	490
	21st to end	Day	32% 15% 22% 18% 10% 2	486
November	1st to 10th	Day	36% 16% 22% 19% 6%	233
	11th to 20th	Day	40% 11% 19% 18% 10% 2	182
	21st to end	Day	32% 18% 23% 12% 15% 1	180
December	1st to 10th	Day	33% 14% 21% 18% 12% 1	180
	11th to 20th	Day	44% 13% 24% 12% 6% 1	180
	21st to end	Day	42% 13% 23% 14% 8% 1	198
January	1st to 10th	Night	45% 8% 16% 17% 12% 2	760
	11th to 20th	Night	41% 8% 13% 23% 14% 1	760
	21st to end	Night	37% 6% 12% 28% 16% 1	836
February	1st to 10th	Night	39% 7% 12% 28% 12% 1	760
	11th to 20th	Night	35% 9% 15% 27% 13%	744
	21st to end	Night	38% 8% 16% 26% 12%	628
March	1st to 10th	Night	37% 8% 16% 26% 13% 1	760
	11th to 20th	Night	34% 8% 16% 29% 12% 1	760
	21st to end	Night	39% 11% 14% 25% 10% 1	836
April	1st to 10th	Night	34% 9% 18% 24% 13% 1	760
	11th to 20th	Night	28% 9% 20% 30% 12% 2	734
	21st to end	Night	28% 7% 16% 33% 15% 1	570
May	1st to 10th	Night	21% 7% 23% 34% 14% 1	409
	11th to 20th	Night	21% 5% 19% 36% 18% 2	374
	21st to end	Night	18% 6% 21% 37% 19%	411
June	1st to 10th	Night	23% 3 21% 38% 14%	380
	11th to 20th	Night	18% 7% 23% 39% 12% 1	380
	21st to end	Night	13% 3 24% 46% 14%	380
July	1st to 10th	Night	6% 4 22% 51% 16% 1	370
	11th to 20th	Night	5% 1 28% 52% 14%	368
	21st to end	Night	4 2 21% 56% 16%	416
August	1st to 10th	Night	5% 3 17% 49% 25% 2	519
	11th to 20th	Night	6% 1 13% 45% 32% 2	564
	21st to end	Night	12% 3 21% 43% 20% 1	745
September	1st to 10th	Night	11% 3 22% 43% 20% 2	760
	11th to 20th	Night	17% 5% 15% 33% 27% 3	760
	21st to end	Night	16% 4 20% 39% 19% 2	760
October	1st to 10th	Night	22% 3 14% 39% 20% 2	760
	11th to 20th	Night	27% 4 13% 31% 21% 3	760
	21st to end	Night	33% 6% 17% 26% 17% 1	836
November	1st to 10th	Night	37% 9% 15% 29% 9%	780
	11th to 20th	Night	41% 8% 14% 24% 11% 1	764
	21st to end	Night	35% 8% 15% 25% 15% 2	760
December	1st to 10th	Night	35% 8% 16% 26% 13% 2	760
	11th to 20th	Night	41% 8% 18% 22% 10% 1	760
	21st to end	Night	47% 9% 18% 18% 8% 1	836

Page generated at 2024-11-08 19:45:37. Version ac07

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