Tumbler Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tumbler Ridge 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	8% 10% 4 9% 6% 6% 6% 5% 7% 8% 32%	105830
	Night	6% 10% 4 10% 6% 6% 6% 5% 7% 8% 33%	101758
Transparency	Day	48% 9% 16% 19% 8% 1	105561
	Night	46% 10% 16% 19% 8% 1	101675
Seeing	Day	20% 19% 29% 20% 10% 2	16612
	Night	16% 18% 29% 25% 11% 1	24414

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	2 10% 5% 12% 7% 9% 9% 5% 8% 9% 25%	1899
	11th to 20th	Day	5% 10% 5% 10% 4 6% 9% 5% 11% 8% 26%	2080
	21st to end	Day	4 13% 4 10% 6% 6% 7% 5% 7% 9% 29%	2442
February	1st to 10th	Day	4 12% 5% 13% 6% 7% 8% 5% 5% 7% 28%	1513
	11th to 20th	Day	2 13% 4 13% 8% 7% 6% 5% 6% 8% 28%	1612
	21st to end	Day	3 12% 7% 13% 8% 8% 8% 5% 5% 5% 26%	1422
March	1st to 10th	Day	1 6% 3 12% 10% 9% 6% 6% 10% 9% 27%	3138
	11th to 20th	Day	5% 12% 4 10% 6% 5% 5% 5% 7% 9% 32%	3387
	21st to end	Day	2 11% 5% 19% 7% 5% 5% 4 6% 7% 29%	4066
April	1st to 10th	Day	4 12% 5% 13% 8% 7% 6% 5% 7% 7% 26%	2280
	11th to 20th	Day	8% 17% 5% 12% 7% 5% 5% 4 6% 6% 26%	2449
	21st to end	Day	10% 14% 5% 10% 6% 5% 6% 4 6% 7% 27%	2660
May	1st to 10th	Day	7% 11% 5% 10% 7% 6% 6% 5% 7% 6% 31%	4420
	11th to 20th	Day	9% 12% 4 10% 7% 7% 7% 5% 6% 7% 26%	4729
	21st to end	Day	14% 13% 5% 12% 7% 6% 6% 4 6% 6% 22%	5509
June	1st to 10th	Day	13% 10% 3 8% 6% 6% 6% 4 6% 8% 29%	3040
	11th to 20th	Day	16% 9% 4 10% 7% 6% 5% 5% 6% 7% 24%	3040
	21st to end	Day	11% 8% 3 8% 7% 6% 6% 5% 7% 8% 31%	3040
July	1st to 10th	Day	13% 5% 2 6% 4 4 5% 3 5% 7% 48%	5060
	11th to 20th	Day	8% 4 2 4 4 4 5% 4 6% 8% 50%	5060
	21st to end	Day	10% 6% 2 6% 6% 7% 7% 6% 7% 9% 35%	5170
August	1st to 10th	Day	8% 6% 2 6% 5% 5% 6% 4 6% 7% 45%	4473
	11th to 20th	Day	12% 7% 2 6% 4 5% 6% 5% 8% 9% 37%	4330
	21st to end	Day	12% 6% 2 8% 6% 6% 6% 5% 6% 7% 35%	4567
September	1st to 10th	Day	12% 8% 3 7% 4 5% 5% 5% 6% 8% 37%	2280
	11th to 20th	Day	12% 10% 3 7% 5% 6% 6% 4 6% 7% 35%	2280
	21st to end	Day	8% 11% 3 8% 5% 6% 7% 5% 7% 9% 30%	2023
October	1st to 10th	Day	9% 12% 3 10% 7% 6% 6% 5% 6% 7% 27%	3180
	11th to 20th	Day	8% 12% 4 9% 6% 5% 6% 5% 7% 8% 31%	3012
	21st to end	Day	5% 12% 4 11% 5% 5% 5% 5% 8% 10% 30%	2916
November	1st to 10th	Day	8% 15% 5% 12% 6% 5% 5% 4 5% 6% 29%	1512
	11th to 20th	Day	5% 13% 5% 10% 6% 7% 6% 5% 6% 7% 30%	1356
	21st to end	Day	3 12% 4 11% 9% 5% 4 6% 9% 8% 30%	1213
December	1st to 10th	Day	5% 10% 5% 13% 6% 5% 5% 5% 6% 9% 31%	1140
	11th to 20th	Day	4 14% 6% 11% 6% 7% 6% 5% 6% 7% 28%	1442
	21st to end	Day	2 9% 3 8% 7% 7% 7% 5% 8% 9% 36%	2090
January	1st to 10th	Night	2 11% 5% 15% 9% 6% 6% 5% 7% 8% 27%	5046
	11th to 20th	Night	4 11% 4 9% 7% 8% 7% 6% 13% 10% 23%	4847
	21st to end	Night	5% 13% 5% 10% 7% 6% 6% 6% 8% 10% 24%	5214
February	1st to 10th	Night	4 13% 5% 12% 7% 6% 6% 5% 7% 7% 26%	2666
	11th to 20th	Night	3 11% 5% 12% 7% 7% 6% 6% 8% 9% 28%	2453
	21st to end	Night	2 12% 6% 14% 8% 6% 7% 5% 6% 7% 26%	2032
March	1st to 10th	Night	1 6% 4 15% 11% 9% 6% 4 6% 8% 29%	3736
	11th to 20th	Night	5% 10% 4 8% 6% 6% 7% 6% 8% 9% 31%	3590
	21st to end	Night	4 11% 4 15% 6% 4 4 4 6% 6% 37%	3586
April	1st to 10th	Night	4 8% 5% 8% 7% 6% 6% 4 8% 8% 35%	1900
	11th to 20th	Night	6% 12% 5% 8% 6% 5% 5% 5% 7% 8% 33%	1679
	21st to end	Night	10% 13% 4 10% 5% 4 6% 4 6% 7% 31%	1520
May	1st to 10th	Night	6% 8% 3 9% 7% 6% 7% 5% 8% 8% 33%	2540
	11th to 20th	Night	10% 10% 3 6% 5% 5% 4 5% 7% 9% 37%	2162
	21st to end	Night	12% 12% 5% 10% 6% 6% 5% 5% 7% 9% 24%	2066
June	1st to 10th	Night	11% 9% 2 10% 6% 5% 6% 4 5% 7% 35%	1140
	11th to 20th	Night	15% 11% 5% 9% 6% 5% 5% 5% 6% 8% 26%	1140
	21st to end	Night	9% 6% 2 7% 6% 5% 6% 5% 8% 9% 38%	1140
July	1st to 10th	Night	9% 5% 2 4 3 4 4 4 5% 8% 52%	1900
	11th to 20th	Night	8% 4 1 4 4 4 4 5% 7% 8% 51%	1900
	21st to end	Night	9% 7% 3 6% 4 5% 6% 5% 8% 9% 37%	2379
August	1st to 10th	Night	8% 5% 2 6% 4 4 4 3 5% 8% 50%	2456
	11th to 20th	Night	12% 5% 1 4 4 4 4 4 7% 8% 46%	2497
	21st to end	Night	9% 7% 3 9% 7% 6% 5% 5% 7% 8% 35%	3095
September	1st to 10th	Night	12% 8% 3 8% 4 5% 4 4 6% 7% 40%	1900
	11th to 20th	Night	10% 9% 2 6% 3 4 4 4 6% 10% 40%	1900
	21st to end	Night	10% 9% 4 7% 6% 5% 5% 4 7% 7% 36%	2156
October	1st to 10th	Night	9% 12% 4 11% 6% 5% 5% 4 6% 8% 29%	3800
	11th to 20th	Night	5% 8% 4 9% 6% 6% 7% 5% 7% 9% 36%	3921
	21st to end	Night	6% 14% 6% 10% 6% 6% 5% 5% 6% 7% 29%	4635
November	1st to 10th	Night	7% 13% 4 10% 7% 5% 4 4 6% 7% 31%	2638
	11th to 20th	Night	3 14% 5% 11% 6% 6% 5% 5% 6% 8% 31%	2804
	21st to end	Night	4 13% 4 10% 7% 6% 6% 5% 8% 9% 28%	2964
December	1st to 10th	Night	3 10% 4 10% 7% 6% 6% 4 7% 8% 34%	3040
	11th to 20th	Night	4 14% 5% 11% 7% 6% 7% 5% 7% 6% 29%	3750
	21st to end	Night	2 8% 4 8% 6% 6% 6% 6% 8% 9% 38%	5566

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	54% 10% 18% 14% 3 1	1899
	11th to 20th	Day	50% 10% 13% 10% 14% 1	2101
	21st to end	Day	46% 18% 20% 11% 4	2442
February	1st to 10th	Day	55% 10% 13% 11% 9% 2	1513
	11th to 20th	Day	55% 7% 15% 15% 7% 1	1621
	21st to end	Day	59% 6% 14% 14% 5% 2	1422
March	1st to 10th	Day	50% 9% 12% 18% 11% 1	3138
	11th to 20th	Day	46% 9% 15% 23% 7%	3387
	21st to end	Day	53% 8% 14% 16% 9%	4066
April	1st to 10th	Day	56% 7% 15% 15% 6%	2280
	11th to 20th	Day	58% 7% 11% 17% 7%	2449
	21st to end	Day	55% 8% 14% 18% 5%	2660
May	1st to 10th	Day	49% 8% 16% 20% 7% 1	4420
	11th to 20th	Day	53% 9% 13% 17% 7% 1	4733
	21st to end	Day	60% 7% 11% 14% 8% 1	5510
June	1st to 10th	Day	52% 8% 13% 19% 7% 1	3040
	11th to 20th	Day	58% 7% 12% 18% 5%	3040
	21st to end	Day	49% 9% 15% 20% 6% 1	3040
July	1st to 10th	Day	36% 6% 10% 22% 24% 2	4981
	11th to 20th	Day	31% 8% 16% 32% 12% 1	4973
	21st to end	Day	42% 10% 20% 22% 7%	5007
August	1st to 10th	Day	35% 9% 15% 31% 10%	4455
	11th to 20th	Day	40% 10% 16% 22% 12%	4372
	21st to end	Day	47% 8% 24% 18% 3	4566
September	1st to 10th	Day	45% 8% 23% 19% 5% 1	2280
	11th to 20th	Day	48% 9% 18% 19% 7%	2280
	21st to end	Day	49% 10% 19% 17% 5% 1	2023
October	1st to 10th	Day	52% 9% 18% 16% 5%	3180
	11th to 20th	Day	48% 9% 19% 21% 3	3012
	21st to end	Day	47% 9% 28% 13% 3	2916
November	1st to 10th	Day	57% 7% 14% 17% 4 1	1512
	11th to 20th	Day	53% 10% 17% 13% 5% 1	1356
	21st to end	Day	50% 11% 18% 13% 7% 1	1213
December	1st to 10th	Day	52% 8% 13% 16% 9% 1	1140
	11th to 20th	Day	54% 10% 14% 16% 5%	1444
	21st to end	Day	39% 11% 19% 20% 10%	2090
January	1st to 10th	Night	54% 10% 14% 15% 6% 1	5046
	11th to 20th	Night	48% 9% 13% 11% 17% 1	4888
	21st to end	Night	52% 15% 16% 11% 6%	5214
February	1st to 10th	Night	55% 8% 14% 12% 10% 1	2666
	11th to 20th	Night	51% 10% 16% 16% 6% 1	2455
	21st to end	Night	54% 8% 12% 18% 6% 2	2032
March	1st to 10th	Night	52% 8% 13% 16% 11% 1	3736
	11th to 20th	Night	44% 11% 13% 22% 10% 1	3591
	21st to end	Night	45% 8% 13% 24% 10%	3586
April	1st to 10th	Night	44% 10% 14% 24% 8% 1	1900
	11th to 20th	Night	49% 8% 13% 20% 9%	1679
	21st to end	Night	52% 7% 12% 21% 7% 1	1520
May	1st to 10th	Night	44% 8% 16% 20% 11% 1	2540
	11th to 20th	Night	40% 10% 14% 27% 8% 1	2162
	21st to end	Night	53% 10% 13% 16% 7%	2066
June	1st to 10th	Night	47% 8% 12% 24% 9%	1140
	11th to 20th	Night	55% 7% 14% 18% 5% 1	1140
	21st to end	Night	41% 9% 19% 24% 6%	1140
July	1st to 10th	Night	29% 7% 15% 31% 17% 2	1870
	11th to 20th	Night	29% 7% 16% 28% 19%	1864
	21st to end	Night	38% 12% 24% 22% 5%	2304
August	1st to 10th	Night	32% 8% 20% 35% 5%	2449
	11th to 20th	Night	32% 9% 18% 28% 12% 1	2521
	21st to end	Night	45% 11% 22% 18% 3	3095
September	1st to 10th	Night	44% 7% 20% 22% 5% 1	1900
	11th to 20th	Night	40% 8% 20% 26% 6%	1900
	21st to end	Night	46% 12% 16% 17% 9%	2156
October	1st to 10th	Night	50% 12% 14% 17% 6%	3800
	11th to 20th	Night	40% 11% 21% 24% 4	3921
	21st to end	Night	53% 9% 18% 16% 5%	4635
November	1st to 10th	Night	51% 10% 15% 17% 6% 1	2638
	11th to 20th	Night	53% 10% 15% 16% 6% 1	2804
	21st to end	Night	50% 11% 17% 15% 6% 1	2964
December	1st to 10th	Night	48% 10% 16% 18% 8% 1	3040
	11th to 20th	Night	52% 13% 12% 17% 6%	3747
	21st to end	Night	39% 12% 19% 23% 8% 1	5566

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	14% 16% 29% 30% 6% 5%	180
	11th to 20th	Day	18% 19% 31% 23% 5% 4	180
	21st to end	Day	21% 26% 26% 17% 9% 1	198
February	1st to 10th	Day	19% 26% 24% 21% 9% 1	180
	11th to 20th	Day	18% 23% 31% 18% 11%	313
	21st to end	Day	19% 22% 37% 15% 6% 1	312
March	1st to 10th	Day	15% 21% 29% 24% 9% 2	460
	11th to 20th	Day	18% 23% 33% 17% 8% 1	460
	21st to end	Day	21% 20% 29% 20% 10% 2	506
April	1st to 10th	Day	20% 24% 30% 18% 6% 2	460
	11th to 20th	Day	23% 19% 30% 18% 8% 2	452
	21st to end	Day	23% 24% 27% 17% 7% 2	460
May	1st to 10th	Day	22% 20% 31% 18% 8% 1	463
	11th to 20th	Day	21% 15% 28% 24% 11% 2	682
	21st to end	Day	20% 16% 25% 24% 12% 3	940
June	1st to 10th	Day	18% 21% 31% 19% 10% 2	870
	11th to 20th	Day	23% 17% 26% 22% 11% 2	870
	21st to end	Day	17% 13% 26% 23% 16% 4	870
July	1st to 10th	Day	17% 13% 26% 28% 14% 2	856
	11th to 20th	Day	16% 13% 31% 22% 15% 3	852
	21st to end	Day	15% 14% 34% 23% 10% 4	758
August	1st to 10th	Day	15% 13% 27% 26% 16% 3	534
	11th to 20th	Day	15% 22% 31% 17% 11% 3	477
	21st to end	Day	17% 22% 32% 17% 8% 3	539
September	1st to 10th	Day	23% 19% 29% 17% 7% 5%	490
	11th to 20th	Day	24% 17% 30% 18% 9% 2	490
	21st to end	Day	24% 28% 28% 13% 7% 1	490
October	1st to 10th	Day	30% 19% 27% 18% 6% 2	490
	11th to 20th	Day	24% 22% 30% 18% 5% 1	405
	21st to end	Day	19% 22% 29% 20% 8% 2	271
November	1st to 10th	Day	26% 26% 27% 12% 8% 1	186
	11th to 20th	Day	21% 31% 31% 14% 4	180
	21st to end	Day	24% 23% 28% 17% 7% 2	180
December	1st to 10th	Day	16% 24% 28% 22% 7% 2	180
	11th to 20th	Day	17% 21% 29% 23% 9% 2	180
	21st to end	Day	18% 17% 30% 23% 11% 1	198
January	1st to 10th	Night	13% 20% 31% 27% 7% 1	1040
	11th to 20th	Night	18% 20% 30% 25% 6%	933
	21st to end	Night	18% 26% 30% 22% 3 1	935
February	1st to 10th	Night	18% 21% 23% 23% 13% 2	763
	11th to 20th	Night	13% 19% 30% 28% 9% 1	744
	21st to end	Night	11% 19% 32% 24% 12% 2	628
March	1st to 10th	Night	12% 18% 30% 29% 9% 1	760
	11th to 20th	Night	10% 21% 34% 25% 10% 1	760
	21st to end	Night	15% 14% 25% 28% 17% 2	836
April	1st to 10th	Night	11% 14% 28% 30% 14% 2	760
	11th to 20th	Night	15% 14% 27% 28% 15% 1	551
	21st to end	Night	18% 15% 26% 26% 14%	380
May	1st to 10th	Night	13% 12% 30% 27% 16% 2	380
	11th to 20th	Night	17% 9% 24% 32% 17% 2	374
	21st to end	Night	20% 10% 20% 27% 20% 2	411
June	1st to 10th	Night	14% 14% 27% 29% 16% 1	380
	11th to 20th	Night	19% 11% 24% 26% 18% 2	380
	21st to end	Night	12% 11% 25% 30% 20% 2	380
July	1st to 10th	Night	12% 7% 27% 36% 17% 1	370
	11th to 20th	Night	16% 9% 25% 29% 20% 1	368
	21st to end	Night	8% 11% 25% 33% 19% 4	416
August	1st to 10th	Night	13% 8% 20% 29% 25% 4	378
	11th to 20th	Night	11% 11% 24% 27% 25% 1	376
	21st to end	Night	13% 10% 31% 26% 18% 1	589
September	1st to 10th	Night	19% 13% 24% 29% 14% 1	760
	11th to 20th	Night	17% 11% 26% 24% 21% 2	760
	21st to end	Night	20% 23% 28% 21% 8% 1	760
October	1st to 10th	Night	23% 16% 26% 26% 9% 1	760
	11th to 20th	Night	17% 20% 30% 25% 7% 1	760
	21st to end	Night	23% 20% 31% 20% 6%	836
November	1st to 10th	Night	19% 22% 29% 20% 9% 1	754
	11th to 20th	Night	18% 26% 33% 19% 4	904
	21st to end	Night	18% 24% 33% 19% 6%	1004
December	1st to 10th	Night	13% 24% 33% 23% 6% 1	1040
	11th to 20th	Night	15% 23% 31% 21% 9% 1	1040
	21st to end	Night	15% 20% 30% 26% 8% 1	1144

Page generated at 2024-11-01 19:47:41. Version ac07

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