Peace River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peace River 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	10% 9% 3 8% 6% 5% 5% 5% 6% 8% 35%	105995
	Night	8% 10% 4 10% 6% 6% 6% 5% 6% 8% 32%	101599
Transparency	Day	45% 6% 17% 23% 7%	105714
	Night	48% 6% 16% 22% 8% 1	101526
Seeing	Day	14% 6% 22% 30% 22% 8%	16667
	Night	13% 5% 21% 38% 20% 3	24622

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	7% 14% 6% 15% 12% 10% 7% 4 6% 6% 13%	1899
	11th to 20th	Day	7% 12% 4 11% 8% 8% 5% 5% 8% 5% 27%	1882
	21st to end	Day	7% 11% 4 11% 9% 6% 6% 5% 6% 8% 28%	2475
February	1st to 10th	Day	8% 14% 4 11% 6% 6% 8% 7% 8% 9% 20%	1520
	11th to 20th	Day	5% 11% 5% 12% 7% 7% 7% 6% 7% 8% 25%	1480
	21st to end	Day	4 11% 5% 13% 8% 8% 7% 6% 7% 9% 22%	1502
March	1st to 10th	Day	3 8% 4 12% 8% 8% 7% 5% 7% 8% 31%	3138
	11th to 20th	Day	4 9% 3 10% 6% 5% 6% 5% 7% 10% 34%	3263
	21st to end	Day	4 10% 4 13% 6% 6% 6% 4 7% 8% 31%	4147
April	1st to 10th	Day	5% 10% 3 7% 8% 7% 5% 5% 7% 8% 35%	2292
	11th to 20th	Day	8% 11% 4 7% 6% 6% 5% 5% 7% 8% 35%	2453
	21st to end	Day	11% 11% 3 8% 7% 6% 4 4 5% 7% 32%	2660
May	1st to 10th	Day	10% 9% 3 7% 5% 5% 5% 4 6% 8% 39%	4604
	11th to 20th	Day	10% 9% 3 8% 5% 5% 5% 5% 7% 8% 35%	4711
	21st to end	Day	12% 8% 3 8% 5% 6% 6% 5% 7% 9% 30%	5509
June	1st to 10th	Day	14% 7% 3 8% 5% 5% 5% 4 6% 7% 36%	3040
	11th to 20th	Day	21% 9% 3 8% 6% 6% 5% 4 6% 6% 27%	3040
	21st to end	Day	11% 7% 2 7% 6% 5% 6% 5% 6% 8% 38%	3040
July	1st to 10th	Day	10% 6% 2 5% 4 4 4 4 6% 8% 46%	5060
	11th to 20th	Day	7% 4 2 6% 5% 5% 6% 5% 7% 9% 44%	5060
	21st to end	Day	15% 5% 2 5% 4 4 4 4 6% 9% 42%	5402
August	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 4 6% 8% 44%	4449
	11th to 20th	Day	11% 6% 3 7% 5% 5% 6% 4 6% 8% 40%	4330
	21st to end	Day	13% 5% 2 8% 5% 4 5% 4 6% 8% 39%	4650
September	1st to 10th	Day	14% 6% 2 6% 5% 4 4 4 5% 9% 41%	2312
	11th to 20th	Day	10% 7% 3 6% 5% 4 6% 4 7% 9% 39%	2209
	21st to end	Day	9% 7% 3 7% 5% 4 5% 4 7% 10% 39%	2090
October	1st to 10th	Day	12% 10% 3 7% 5% 5% 5% 5% 6% 8% 33%	3193
	11th to 20th	Day	12% 9% 4 9% 5% 4 5% 4 6% 8% 34%	2842
	21st to end	Day	9% 13% 5% 10% 5% 4 4 4 6% 8% 31%	3080
November	1st to 10th	Day	10% 13% 5% 11% 7% 5% 7% 5% 6% 7% 25%	1359
	11th to 20th	Day	7% 12% 5% 13% 7% 6% 6% 5% 6% 8% 22%	1330
	21st to end	Day	7% 16% 5% 12% 6% 7% 5% 4 5% 7% 27%	1302
December	1st to 10th	Day	7% 14% 5% 11% 9% 5% 6% 7% 5% 7% 24%	1140
	11th to 20th	Day	11% 12% 3 11% 10% 7% 6% 5% 6% 9% 21%	1442
	21st to end	Day	4 8% 4 9% 6% 6% 5% 5% 7% 9% 38%	2090
January	1st to 10th	Night	6% 15% 8% 18% 9% 6% 5% 4 6% 6% 17%	5046
	11th to 20th	Night	6% 11% 4 11% 6% 6% 7% 6% 9% 7% 27%	5016
	21st to end	Night	9% 14% 5% 12% 8% 7% 6% 4 6% 7% 22%	5212
February	1st to 10th	Night	7% 12% 6% 11% 7% 6% 6% 5% 6% 8% 26%	2660
	11th to 20th	Night	5% 13% 5% 12% 8% 7% 5% 5% 5% 7% 28%	2586
	21st to end	Night	3 10% 4 12% 7% 6% 6% 5% 8% 9% 31%	1950
March	1st to 10th	Night	3 9% 4 11% 7% 8% 6% 5% 7% 8% 31%	3736
	11th to 20th	Night	5% 9% 3 8% 6% 6% 6% 5% 8% 11% 33%	3716
	21st to end	Night	4 11% 4 12% 6% 6% 6% 4 5% 6% 35%	3502
April	1st to 10th	Night	6% 12% 3 8% 5% 6% 5% 5% 6% 7% 37%	1887
	11th to 20th	Night	9% 11% 3 9% 6% 5% 5% 5% 7% 8% 32%	1673
	21st to end	Night	11% 12% 4 7% 6% 7% 5% 5% 5% 7% 30%	1520
May	1st to 10th	Night	8% 7% 3 10% 6% 6% 5% 3 5% 7% 39%	2355
	11th to 20th	Night	8% 7% 3 8% 6% 6% 6% 5% 6% 8% 35%	2181
	21st to end	Night	12% 7% 3 8% 5% 4 5% 4 7% 9% 33%	2066
June	1st to 10th	Night	13% 6% 3 8% 6% 6% 6% 4 7% 7% 35%	1140
	11th to 20th	Night	17% 8% 3 7% 6% 6% 5% 4 7% 8% 28%	1140
	21st to end	Night	10% 6% 2 6% 5% 5% 5% 5% 8% 9% 39%	1140
July	1st to 10th	Night	12% 6% 2 6% 4 4 5% 4 6% 8% 44%	1900
	11th to 20th	Night	8% 6% 3 7% 6% 5% 6% 5% 8% 9% 38%	1900
	21st to end	Night	12% 5% 2 5% 5% 4 4 5% 7% 10% 41%	2149
August	1st to 10th	Night	10% 6% 3 6% 4 5% 5% 4 6% 7% 45%	2465
	11th to 20th	Night	9% 7% 2 6% 5% 4 4 4 6% 7% 45%	2497
	21st to end	Night	13% 6% 2 6% 5% 4 5% 4 8% 8% 39%	3013
September	1st to 10th	Night	13% 6% 3 7% 5% 5% 5% 5% 6% 8% 39%	1867
	11th to 20th	Night	9% 7% 2 7% 5% 4 6% 4 6% 8% 41%	1971
	21st to end	Night	9% 9% 2 7% 5% 6% 4 4 6% 8% 41%	2090
October	1st to 10th	Night	9% 11% 3 9% 5% 5% 5% 4 6% 8% 35%	3781
	11th to 20th	Night	8% 8% 3 7% 5% 5% 4 4 6% 9% 40%	4086
	21st to end	Night	8% 12% 3 9% 6% 6% 6% 4 6% 7% 32%	4475
November	1st to 10th	Night	11% 14% 5% 11% 6% 5% 5% 5% 6% 6% 26%	2798
	11th to 20th	Night	8% 14% 4 11% 7% 7% 7% 5% 6% 6% 23%	2850
	21st to end	Night	6% 15% 5% 12% 8% 5% 5% 4 6% 7% 25%	2875
December	1st to 10th	Night	8% 13% 5% 12% 9% 7% 6% 4 6% 6% 24%	3040
	11th to 20th	Night	8% 15% 5% 11% 7% 5% 5% 5% 7% 7% 23%	3750
	21st to end	Night	3 8% 4 9% 7% 6% 6% 4 7% 9% 37%	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	69% 6% 12% 10% 4	1899
	11th to 20th	Day	55% 4 10% 13% 16% 2	1900
	21st to end	Day	54% 7% 19% 15% 4	2475
February	1st to 10th	Day	55% 6% 15% 14% 9%	1520
	11th to 20th	Day	52% 7% 16% 18% 6%	1488
	21st to end	Day	55% 6% 14% 17% 8%	1502
March	1st to 10th	Day	48% 5% 17% 25% 5%	3138
	11th to 20th	Day	41% 11% 20% 22% 6%	3263
	21st to end	Day	49% 6% 14% 23% 8%	4147
April	1st to 10th	Day	44% 6% 17% 25% 9%	2292
	11th to 20th	Day	45% 5% 14% 24% 10% 2	2453
	21st to end	Day	51% 6% 12% 23% 8%	2660
May	1st to 10th	Day	41% 6% 12% 25% 15% 1	4604
	11th to 20th	Day	45% 6% 11% 27% 10% 1	4715
	21st to end	Day	46% 7% 14% 23% 10% 1	5510
June	1st to 10th	Day	46% 5% 14% 25% 9% 1	3040
	11th to 20th	Day	56% 7% 13% 19% 5%	3040
	21st to end	Day	43% 6% 18% 25% 8%	3040
July	1st to 10th	Day	34% 6% 21% 30% 8%	4981
	11th to 20th	Day	34% 6% 19% 28% 11% 1	4973
	21st to end	Day	38% 6% 23% 26% 6%	5231
August	1st to 10th	Day	36% 7% 21% 33% 3	4431
	11th to 20th	Day	41% 6% 18% 25% 10%	4372
	21st to end	Day	42% 6% 26% 23% 3	4649
September	1st to 10th	Day	41% 6% 25% 24% 4	2312
	11th to 20th	Day	40% 6% 25% 25% 5%	2209
	21st to end	Day	39% 7% 20% 24% 9%	2090
October	1st to 10th	Day	47% 7% 20% 22% 5%	3193
	11th to 20th	Day	47% 4 19% 26% 4	2842
	21st to end	Day	51% 6% 22% 19% 3	3080
November	1st to 10th	Day	57% 7% 14% 20% 3	1359
	11th to 20th	Day	56% 8% 18% 15% 3	1330
	21st to end	Day	54% 7% 16% 17% 4 2	1302
December	1st to 10th	Day	57% 7% 12% 15% 9% 1	1140
	11th to 20th	Day	59% 8% 12% 17% 4	1444
	21st to end	Day	41% 6% 15% 26% 9% 2	2090
January	1st to 10th	Night	65% 7% 10% 13% 5%	5046
	11th to 20th	Night	52% 6% 11% 12% 18% 1	5060
	21st to end	Night	58% 8% 17% 12% 5%	5212
February	1st to 10th	Night	54% 5% 14% 18% 8% 1	2660
	11th to 20th	Night	54% 6% 15% 18% 7% 1	2588
	21st to end	Night	46% 6% 17% 22% 8%	1950
March	1st to 10th	Night	46% 6% 15% 24% 8%	3736
	11th to 20th	Night	41% 7% 20% 25% 6%	3717
	21st to end	Night	46% 7% 11% 26% 10%	3502
April	1st to 10th	Night	44% 5% 10% 26% 14% 1	1887
	11th to 20th	Night	47% 5% 11% 23% 13% 2	1673
	21st to end	Night	52% 5% 10% 22% 10% 1	1520
May	1st to 10th	Night	43% 5% 12% 25% 16% 1	2355
	11th to 20th	Night	42% 7% 10% 26% 14% 2	2181
	21st to end	Night	43% 7% 14% 28% 7% 1	2066
June	1st to 10th	Night	47% 5% 12% 25% 10% 1	1140
	11th to 20th	Night	51% 5% 15% 22% 6%	1140
	21st to end	Night	38% 7% 18% 26% 11%	1140
July	1st to 10th	Night	37% 6% 16% 30% 12%	1870
	11th to 20th	Night	40% 6% 17% 24% 12% 1	1864
	21st to end	Night	35% 6% 25% 25% 8% 1	2081
August	1st to 10th	Night	35% 7% 18% 36% 3	2458
	11th to 20th	Night	36% 7% 19% 24% 14%	2521
	21st to end	Night	40% 5% 27% 23% 4	3013
September	1st to 10th	Night	42% 7% 19% 24% 8% 1	1867
	11th to 20th	Night	39% 5% 21% 27% 7%	1971
	21st to end	Night	41% 6% 17% 26% 10%	2090
October	1st to 10th	Night	46% 6% 17% 20% 9% 1	3781
	11th to 20th	Night	40% 5% 19% 30% 6%	4086
	21st to end	Night	50% 6% 19% 21% 4	4475
November	1st to 10th	Night	57% 7% 14% 20% 3	2798
	11th to 20th	Night	58% 8% 14% 16% 4	2850
	21st to end	Night	56% 7% 17% 15% 4 1	2875
December	1st to 10th	Night	58% 6% 11% 16% 8% 1	3040
	11th to 20th	Night	57% 7% 13% 17% 5%	3747
	21st to end	Night	43% 5% 18% 26% 7% 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	11% 4 22% 37% 22% 4	180
	11th to 20th	Day	18% 4 20% 31% 23% 4	180
	21st to end	Day	14% 2 24% 32% 25% 4	198
February	1st to 10th	Day	12% 4 29% 30% 17% 8%	180
	11th to 20th	Day	9% 4 26% 32% 20% 9%	180
	21st to end	Day	8% 4 27% 34% 19% 8%	340
March	1st to 10th	Day	7% 5% 25% 33% 22% 7%	460
	11th to 20th	Day	9% 5% 26% 32% 23% 6%	460
	21st to end	Day	15% 3 24% 31% 20% 7%	506
April	1st to 10th	Day	10% 6% 24% 31% 21% 8%	460
	11th to 20th	Day	12% 9% 25% 25% 21% 9%	452
	21st to end	Day	15% 10% 24% 28% 16% 7%	460
May	1st to 10th	Day	14% 7% 27% 25% 22% 5%	569
	11th to 20th	Day	12% 6% 17% 34% 22% 8%	679
	21st to end	Day	15% 5% 17% 29% 26% 8%	940
June	1st to 10th	Day	16% 7% 23% 28% 22% 4	870
	11th to 20th	Day	23% 6% 16% 27% 21% 7%	870
	21st to end	Day	12% 6% 16% 27% 26% 13%	870
July	1st to 10th	Day	13% 4 17% 28% 28% 9%	856
	11th to 20th	Day	12% 5% 14% 29% 29% 11%	852
	21st to end	Day	14% 4 17% 31% 23% 11%	899
August	1st to 10th	Day	15% 6% 15% 23% 25% 17%	522
	11th to 20th	Day	9% 9% 25% 31% 20% 5%	477
	21st to end	Day	16% 6% 26% 27% 18% 7%	539
September	1st to 10th	Day	17% 5% 24% 29% 19% 7%	490
	11th to 20th	Day	13% 7% 21% 30% 20% 9%	490
	21st to end	Day	12% 11% 30% 27% 17% 4	490
October	1st to 10th	Day	16% 10% 23% 30% 17% 4	467
	11th to 20th	Day	19% 5% 24% 29% 18% 4	300
	21st to end	Day	18% 4 25% 35% 13% 5%	325
November	1st to 10th	Day	13% 4 31% 30% 18% 4	188
	11th to 20th	Day	14% 4 32% 27% 19% 4	180
	21st to end	Day	11% 7% 32% 32% 17% 1	180
December	1st to 10th	Day	6% 6% 29% 34% 18% 6%	180
	11th to 20th	Day	11% 7% 26% 33% 21% 3	180
	21st to end	Day	10% 3 18% 42% 21% 7%	198
January	1st to 10th	Night	13% 4 23% 40% 17% 3	1040
	11th to 20th	Night	13% 5% 24% 37% 18% 2	1040
	21st to end	Night	17% 7% 25% 35% 14% 2	983
February	1st to 10th	Night	13% 4 22% 36% 21% 4	760
	11th to 20th	Night	13% 3 19% 44% 19% 2	744
	21st to end	Night	6% 3 25% 40% 22% 4	628
March	1st to 10th	Night	9% 4 24% 36% 23% 4	760
	11th to 20th	Night	13% 4 21% 42% 18% 2	760
	21st to end	Night	13% 4 18% 38% 25% 3	836
April	1st to 10th	Night	11% 4 19% 39% 23% 3	747
	11th to 20th	Night	13% 4 21% 34% 24% 4	545
	21st to end	Night	16% 2 22% 37% 20% 2	380
May	1st to 10th	Night	14% 5% 16% 38% 26% 2	380
	11th to 20th	Night	10% 5% 22% 36% 25% 3	374
	21st to end	Night	17% 3 12% 39% 27% 3	411
June	1st to 10th	Night	15% 4 11% 42% 28%	380
	11th to 20th	Night	19% 3 12% 34% 27% 4	380
	21st to end	Night	12% 3 14% 38% 29% 4	380
July	1st to 10th	Night	14% 4 13% 35% 32% 3	370
	11th to 20th	Night	12% 3 9% 38% 34% 4	368
	21st to end	Night	14% 1 12% 36% 34% 3	416
August	1st to 10th	Night	10% 3 8% 33% 39% 8%	378
	11th to 20th	Night	7% 2 16% 48% 24% 2	376
	21st to end	Night	16% 2 15% 41% 23% 3	546
September	1st to 10th	Night	17% 2 14% 37% 26% 4	727
	11th to 20th	Night	11% 3 17% 40% 27% 3	760
	21st to end	Night	14% 6% 26% 34% 16% 4	760
October	1st to 10th	Night	14% 6% 22% 39% 17% 2	760
	11th to 20th	Night	14% 5% 22% 39% 17% 2	760
	21st to end	Night	19% 7% 20% 38% 14% 2	836
November	1st to 10th	Night	17% 7% 23% 36% 16% 2	900
	11th to 20th	Night	14% 8% 25% 39% 13% 1	950
	21st to end	Night	14% 6% 27% 40% 12% 2	963
December	1st to 10th	Night	14% 5% 27% 36% 14% 3	1040
	11th to 20th	Night	14% 5% 25% 38% 15% 2	1040
	21st to end	Night	11% 4 23% 38% 21% 3	1144

Page generated at 2024-11-03 00:11:24. Version ac07

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