Nakusp
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nakusp clear sky chart from 2005-11-06 to 2024-11-04.

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	10% 11% 4 9% 6% 6% 6% 4 6% 7% 31%	105643
	Night	12% 15% 5% 11% 6% 5% 5% 4 5% 6% 26%	101917
Transparency	Day	52% 9% 14% 17% 7% 1	105403
	Night	57% 9% 13% 15% 6% 1	101803
Seeing	Day	19% 17% 30% 25% 9% 1	15262
	Night	22% 11% 30% 28% 9%	23979

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% 24% 9% 18% 9% 8% 6% 3 3 3 4	2356
	11th to 20th	Day	12% 19% 6% 12% 6% 6% 7% 7% 7% 8% 11%	2516
	21st to end	Day	11% 21% 7% 18% 11% 6% 6% 3 5% 5% 8%	2794
February	1st to 10th	Day	13% 22% 6% 13% 9% 7% 4 3 6% 4 14%	1520
	11th to 20th	Day	8% 19% 8% 15% 8% 5% 5% 4 5% 5% 20%	1659
	21st to end	Day	6% 20% 7% 14% 9% 5% 6% 5% 6% 6% 17%	1570
March	1st to 10th	Day	6% 17% 6% 12% 9% 8% 7% 6% 7% 6% 16%	3138
	11th to 20th	Day	7% 10% 4 9% 6% 7% 7% 5% 6% 8% 32%	3237
	21st to end	Day	8% 19% 6% 13% 7% 7% 6% 4 6% 6% 18%	4165
April	1st to 10th	Day	10% 17% 5% 13% 7% 6% 6% 4 6% 7% 19%	2280
	11th to 20th	Day	11% 13% 6% 10% 7% 7% 7% 5% 7% 7% 23%	2343
	21st to end	Day	12% 14% 5% 11% 8% 6% 6% 5% 6% 6% 23%	2526
May	1st to 10th	Day	10% 11% 4 10% 7% 5% 6% 4 6% 8% 31%	4420
	11th to 20th	Day	10% 9% 3 9% 6% 6% 6% 5% 7% 10% 27%	4377
	21st to end	Day	14% 14% 4 10% 7% 6% 7% 5% 6% 6% 19%	5129
June	1st to 10th	Day	19% 10% 4 8% 6% 6% 5% 4 5% 7% 26%	2850
	11th to 20th	Day	19% 11% 4 9% 7% 6% 7% 5% 6% 7% 21%	2866
	21st to end	Day	10% 6% 3 8% 7% 6% 6% 5% 6% 7% 36%	3040
July	1st to 10th	Day	6% 3 2 4 4 4 4 3 6% 6% 57%	4781
	11th to 20th	Day	3 2 1 3 3 3 3 3 4 6% 67%	4489
	21st to end	Day	5% 3 1 4 3 4 4 4 6% 9% 58%	4790
August	1st to 10th	Day	3 3 1 4 3 4 4 4 7% 7% 58%	4401
	11th to 20th	Day	6% 4 1 4 3 4 5% 5% 7% 9% 51%	4277
	21st to end	Day	9% 5% 2 6% 4 5% 5% 5% 6% 9% 45%	4320
September	1st to 10th	Day	8% 6% 2 7% 4 5% 6% 4 4 8% 46%	2280
	11th to 20th	Day	11% 8% 3 7% 6% 5% 4 4 5% 8% 38%	2199
	21st to end	Day	14% 9% 3 9% 5% 5% 5% 4 6% 7% 33%	2090
October	1st to 10th	Day	11% 7% 3 9% 5% 6% 7% 4 6% 8% 34%	3283
	11th to 20th	Day	16% 10% 3 9% 7% 6% 5% 4 6% 7% 27%	2943
	21st to end	Day	16% 12% 5% 10% 6% 5% 6% 3 5% 6% 26%	3101
November	1st to 10th	Day	20% 17% 6% 14% 8% 8% 5% 4 4 5% 10%	1679
	11th to 20th	Day	16% 19% 5% 11% 8% 7% 6% 5% 5% 6% 14%	1440
	21st to end	Day	13% 21% 6% 15% 10% 7% 5% 3 4 5% 11%	1330
December	1st to 10th	Day	13% 19% 5% 13% 10% 7% 6% 4 6% 5% 10%	1330
	11th to 20th	Day	12% 25% 9% 16% 7% 8% 6% 4 5% 4 5%	1682
	21st to end	Day	10% 18% 7% 16% 10% 11% 8% 4 4 4 8%	2442
January	1st to 10th	Night	15% 34% 8% 14% 6% 5% 4 3 3 3 4	4616
	11th to 20th	Night	12% 18% 6% 15% 8% 7% 8% 4 7% 8% 6%	4382
	21st to end	Night	16% 27% 8% 18% 8% 6% 4 3 4 4 5%	4862
February	1st to 10th	Night	12% 27% 7% 15% 7% 5% 5% 4 4 4 9%	2660
	11th to 20th	Night	12% 21% 8% 14% 7% 5% 5% 4 5% 5% 16%	2407
	21st to end	Night	8% 24% 8% 15% 8% 6% 5% 4 5% 6% 12%	1884
March	1st to 10th	Night	7% 16% 6% 14% 9% 7% 6% 4 6% 6% 19%	3736
	11th to 20th	Night	7% 16% 4 8% 5% 4 5% 3 4 6% 37%	3727
	21st to end	Night	11% 20% 5% 12% 7% 5% 5% 4 6% 6% 18%	3488
April	1st to 10th	Night	9% 14% 4 11% 6% 5% 6% 5% 7% 7% 26%	1900
	11th to 20th	Night	10% 15% 5% 8% 6% 6% 5% 5% 6% 6% 27%	1787
	21st to end	Night	12% 12% 4 8% 5% 5% 4 5% 6% 7% 32%	1652
May	1st to 10th	Night	9% 9% 3 8% 5% 6% 6% 4 6% 8% 35%	2540
	11th to 20th	Night	8% 9% 4 9% 4 5% 6% 4 6% 8% 35%	2516
	21st to end	Night	17% 13% 4 8% 6% 5% 5% 5% 6% 7% 24%	2445
June	1st to 10th	Night	18% 10% 3 7% 4 4 5% 5% 6% 6% 32%	1330
	11th to 20th	Night	17% 9% 3 7% 5% 6% 6% 5% 6% 9% 27%	1304
	21st to end	Night	7% 6% 2 7% 6% 5% 5% 4 6% 9% 44%	1140
July	1st to 10th	Night	6% 4 1 4 4 4 4 3 5% 6% 59%	2174
	11th to 20th	Night	4 2 1 4 3 3 4 3 5% 6% 65%	2467
	21st to end	Night	6% 2 1 4 4 3 4 3 7% 7% 58%	2762
August	1st to 10th	Night	3 2 1 4 2 3 4 4 7% 8% 61%	2529
	11th to 20th	Night	4 3 2 6% 4 4 4 3 8% 9% 52%	2551
	21st to end	Night	11% 5% 3 6% 4 3 4 4 6% 7% 48%	3338
September	1st to 10th	Night	8% 5% 2 5% 5% 4 4 4 4 7% 52%	1900
	11th to 20th	Night	10% 8% 3 6% 4 4 3 3 5% 7% 46%	1981
	21st to end	Night	12% 9% 2 8% 4 4 4 4 5% 7% 40%	2090
October	1st to 10th	Night	10% 8% 3 8% 4 5% 5% 4 6% 7% 40%	3694
	11th to 20th	Night	17% 10% 3 8% 5% 5% 4 4 5% 6% 32%	3987
	21st to end	Night	17% 14% 4 9% 6% 5% 5% 4 5% 6% 25%	4457
November	1st to 10th	Night	21% 20% 5% 12% 7% 6% 6% 3 5% 5% 11%	2469
	11th to 20th	Night	16% 22% 5% 13% 8% 6% 6% 4 4 4 11%	2718
	21st to end	Night	14% 22% 6% 15% 9% 7% 6% 3 4 4 10%	2850
December	1st to 10th	Night	14% 22% 6% 14% 9% 6% 5% 4 5% 5% 11%	2850
	11th to 20th	Night	14% 25% 9% 20% 10% 7% 5% 3 3 2 4	3510
	21st to end	Night	11% 21% 7% 15% 9% 9% 7% 4 5% 5% 6%	5214

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	81% 10% 5% 3 1	2356
	11th to 20th	Day	63% 10% 13% 8% 5% 1	2540
	21st to end	Day	79% 11% 5% 4 1	2794
February	1st to 10th	Day	72% 8% 9% 6% 4 1	1520
	11th to 20th	Day	67% 9% 11% 8% 4 1	1668
	21st to end	Day	69% 8% 11% 8% 3	1570
March	1st to 10th	Day	65% 12% 9% 9% 5%	3138
	11th to 20th	Day	47% 13% 20% 17% 2	3237
	21st to end	Day	66% 12% 11% 8% 3	4165
April	1st to 10th	Day	66% 10% 14% 9% 2	2280
	11th to 20th	Day	61% 10% 13% 14% 3	2343
	21st to end	Day	63% 8% 13% 13% 2	2526
May	1st to 10th	Day	51% 10% 13% 23% 4	4420
	11th to 20th	Day	52% 12% 14% 19% 3	4380
	21st to end	Day	63% 11% 12% 12% 2	5130
June	1st to 10th	Day	61% 8% 11% 14% 5% 1	2850
	11th to 20th	Day	63% 10% 10% 13% 4	2866
	21st to end	Day	48% 10% 13% 20% 9% 1	3040
July	1st to 10th	Day	29% 6% 10% 24% 23% 8%	4707
	11th to 20th	Day	20% 5% 10% 28% 30% 8%	4411
	21st to end	Day	24% 5% 15% 29% 21% 5%	4639
August	1st to 10th	Day	23% 7% 18% 35% 15% 2	4384
	11th to 20th	Day	29% 6% 26% 28% 9% 1	4319
	21st to end	Day	38% 8% 22% 26% 6% 1	4319
September	1st to 10th	Day	38% 7% 16% 27% 10% 2	2280
	11th to 20th	Day	43% 9% 14% 24% 10% 1	2199
	21st to end	Day	50% 9% 17% 15% 7% 1	2090
October	1st to 10th	Day	48% 8% 26% 16% 2	3283
	11th to 20th	Day	53% 7% 18% 20% 2	2943
	21st to end	Day	58% 9% 18% 14% 2	3101
November	1st to 10th	Day	75% 10% 8% 7% 1	1679
	11th to 20th	Day	70% 11% 10% 7% 3	1440
	21st to end	Day	71% 11% 11% 5% 2	1330
December	1st to 10th	Day	70% 10% 10% 9% 1	1330
	11th to 20th	Day	80% 10% 6% 3 2	1684
	21st to end	Day	70% 12% 8% 6% 3	2442
January	1st to 10th	Night	84% 7% 4 3 1	4616
	11th to 20th	Night	70% 8% 7% 9% 5% 1	4420
	21st to end	Night	84% 7% 4 3 1	4862
February	1st to 10th	Night	76% 7% 7% 6% 4	2660
	11th to 20th	Night	66% 10% 11% 9% 4 1	2409
	21st to end	Night	69% 8% 10% 9% 4	1884
March	1st to 10th	Night	60% 12% 11% 12% 5%	3736
	11th to 20th	Night	48% 8% 25% 16% 3	3728
	21st to end	Night	63% 13% 10% 12% 3	3488
April	1st to 10th	Night	54% 13% 17% 12% 4	1900
	11th to 20th	Night	55% 9% 15% 14% 5% 1	1787
	21st to end	Night	51% 10% 15% 18% 5%	1652
May	1st to 10th	Night	47% 10% 16% 21% 6%	2540
	11th to 20th	Night	40% 15% 17% 23% 5%	2516
	21st to end	Night	55% 14% 13% 16% 3	2445
June	1st to 10th	Night	52% 9% 12% 18% 7% 1	1330
	11th to 20th	Night	55% 11% 12% 17% 6%	1304
	21st to end	Night	38% 9% 16% 26% 10% 1	1140
July	1st to 10th	Night	27% 6% 9% 23% 25% 9%	2139
	11th to 20th	Night	20% 5% 10% 25% 30% 10%	2422
	21st to end	Night	26% 5% 12% 28% 21% 9%	2674
August	1st to 10th	Night	20% 6% 16% 43% 13% 3	2521
	11th to 20th	Night	28% 6% 23% 30% 12% 1	2575
	21st to end	Night	36% 7% 23% 25% 8% 1	3338
September	1st to 10th	Night	32% 6% 16% 29% 14% 2	1900
	11th to 20th	Night	39% 7% 13% 26% 12% 2	1981
	21st to end	Night	43% 9% 20% 18% 9% 1	2090
October	1st to 10th	Night	44% 9% 22% 21% 4	3694
	11th to 20th	Night	50% 7% 20% 20% 4	3987
	21st to end	Night	59% 9% 16% 14% 1	4457
November	1st to 10th	Night	72% 10% 9% 7% 3	2469
	11th to 20th	Night	72% 9% 9% 6% 3	2718
	21st to end	Night	74% 9% 9% 6% 1	2850
December	1st to 10th	Night	71% 9% 10% 8% 2	2850
	11th to 20th	Night	84% 8% 6% 3	3507
	21st to end	Night	75% 10% 8% 4 3	5214

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	22% 22% 31% 15% 9% 1	180
	11th to 20th	Day	26% 24% 28% 16% 6% 1	180
	21st to end	Day	23% 20% 33% 16% 8% 1	198
February	1st to 10th	Day	28% 26% 31% 12% 3	180
	11th to 20th	Day	19% 22% 36% 15% 8%	337
	21st to end	Day	20% 20% 31% 21% 7% 1	382
March	1st to 10th	Day	20% 28% 30% 17% 5%	460
	11th to 20th	Day	20% 26% 24% 21% 8%	460
	21st to end	Day	22% 20% 28% 22% 7% 1	506
April	1st to 10th	Day	22% 22% 31% 20% 4 1	460
	11th to 20th	Day	23% 20% 28% 20% 9% 1	452
	21st to end	Day	20% 20% 27% 24% 7% 2	460
May	1st to 10th	Day	17% 18% 28% 26% 10% 1	463
	11th to 20th	Day	18% 13% 28% 25% 15% 1	488
	21st to end	Day	18% 14% 25% 28% 13% 1	715
June	1st to 10th	Day	23% 16% 32% 23% 5%	680
	11th to 20th	Day	23% 16% 29% 24% 7% 1	696
	21st to end	Day	13% 12% 30% 33% 11% 1	870
July	1st to 10th	Day	15% 9% 28% 37% 11% 1	699
	11th to 20th	Day	10% 14% 32% 30% 12% 2	524
	21st to end	Day	8% 10% 34% 35% 10% 3	531
August	1st to 10th	Day	8% 11% 30% 33% 14% 3	487
	11th to 20th	Day	9% 12% 29% 33% 13% 3	477
	21st to end	Day	12% 16% 28% 29% 13% 1	539
September	1st to 10th	Day	15% 14% 31% 27% 11% 2	490
	11th to 20th	Day	17% 15% 30% 28% 10% 1	490
	21st to end	Day	20% 22% 30% 19% 9%	490
October	1st to 10th	Day	22% 16% 29% 23% 11%	490
	11th to 20th	Day	27% 14% 28% 19% 12%	362
	21st to end	Day	29% 20% 29% 18% 3 1	330
November	1st to 10th	Day	32% 17% 28% 18% 4	268
	11th to 20th	Day	29% 16% 31% 16% 8%	180
	21st to end	Day	22% 16% 32% 22% 5% 3	180
December	1st to 10th	Day	26% 17% 24% 20% 13% 1	180
	11th to 20th	Day	28% 16% 36% 16% 4 1	180
	21st to end	Day	25% 13% 38% 19% 5%	198
January	1st to 10th	Night	34% 17% 28% 18% 4	879
	11th to 20th	Night	29% 12% 34% 21% 4	760
	21st to end	Night	24% 15% 33% 25% 4	836
February	1st to 10th	Night	27% 14% 33% 19% 6%	760
	11th to 20th	Night	23% 13% 34% 25% 5%	744
	21st to end	Night	19% 12% 33% 25% 10%	628
March	1st to 10th	Night	21% 15% 33% 23% 8%	760
	11th to 20th	Night	22% 15% 29% 29% 5%	760
	21st to end	Night	21% 12% 33% 24% 10%	836
April	1st to 10th	Night	18% 12% 31% 29% 11%	760
	11th to 20th	Night	22% 11% 33% 29% 6%	659
	21st to end	Night	19% 9% 30% 33% 8%	512
May	1st to 10th	Night	12% 9% 31% 35% 12%	380
	11th to 20th	Night	16% 7% 28% 38% 12%	374
	21st to end	Night	19% 8% 27% 36% 10%	411
June	1st to 10th	Night	23% 12% 29% 28% 8%	380
	11th to 20th	Night	21% 11% 25% 32% 11%	380
	21st to end	Night	11% 6% 33% 36% 14%	380
July	1st to 10th	Night	9% 5% 25% 50% 10% 1	370
	11th to 20th	Night	7% 4 27% 48% 14%	368
	21st to end	Night	5% 2 27% 47% 18%	416
August	1st to 10th	Night	6% 3 16% 47% 28%	378
	11th to 20th	Night	8% 3 19% 44% 25%	404
	21st to end	Night	9% 5% 23% 46% 16%	741
September	1st to 10th	Night	11% 6% 27% 39% 17%	760
	11th to 20th	Night	17% 7% 19% 36% 20% 1	760
	21st to end	Night	20% 8% 31% 30% 11%	760
October	1st to 10th	Night	19% 8% 29% 34% 9%	760
	11th to 20th	Night	27% 8% 28% 30% 7%	760
	21st to end	Night	31% 11% 33% 21% 6%	836
November	1st to 10th	Night	36% 13% 30% 18% 4	754
	11th to 20th	Night	31% 17% 28% 19% 4	818
	21st to end	Night	29% 13% 31% 21% 6%	950
December	1st to 10th	Night	27% 11% 35% 22% 5%	950
	11th to 20th	Night	29% 13% 37% 19% 3	950
	21st to end	Night	29% 13% 38% 16% 4	1045

Page generated at 2024-11-01 19:47:29. Version ac07

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