Melfort
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Melfort clear sky chart from 2005-11-06 to 2025-03-27.

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% 4 6% 8% 36%	111972
	Night	8% 10% 4 10% 6% 6% 5% 4 6% 7% 34%	116006
Transparency	Day	46% 5% 17% 24% 7% 1	111711
	Night	48% 5% 15% 23% 8% 1	115913
Seeing	Day	15% 7% 27% 30% 17% 5%	16310
	Night	14% 5% 29% 35% 15% 2	25867

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	5% 15% 5% 16% 8% 6% 6% 4 7% 9% 18%	2741
	11th to 20th	Day	5% 8% 3 12% 12% 9% 6% 7% 7% 7% 24%	3159
	21st to end	Day	5% 14% 6% 14% 8% 6% 5% 3 6% 7% 26%	3930
February	1st to 10th	Day	7% 11% 4 13% 7% 7% 7% 6% 8% 8% 22%	1600
	11th to 20th	Day	6% 11% 4 10% 6% 6% 8% 6% 7% 7% 30%	1728
	21st to end	Day	4 12% 6% 15% 10% 6% 5% 4 6% 7% 26%	1576
March	1st to 10th	Day	7% 13% 6% 10% 8% 8% 6% 4 6% 7% 25%	3230
	11th to 20th	Day	8% 10% 4 10% 6% 6% 5% 5% 6% 8% 32%	3401
	21st to end	Day	7% 10% 3 7% 5% 5% 5% 4 7% 7% 42%	4200
April	1st to 10th	Day	6% 12% 3 7% 5% 4 5% 5% 5% 7% 41%	2280
	11th to 20th	Day	13% 13% 4 9% 6% 4 4 3 6% 8% 30%	2348
	21st to end	Day	12% 9% 4 9% 5% 5% 5% 4 5% 9% 33%	2660
May	1st to 10th	Day	14% 11% 3 7% 5% 4 5% 4 6% 7% 34%	4430
	11th to 20th	Day	11% 8% 3 8% 6% 6% 5% 5% 5% 7% 36%	4465
	21st to end	Day	19% 10% 3 7% 5% 5% 4 3 5% 6% 33%	5347
June	1st to 10th	Day	17% 7% 3 7% 6% 5% 6% 4 7% 7% 31%	3040
	11th to 20th	Day	23% 9% 2 8% 5% 5% 6% 4 6% 6% 26%	3040
	21st to end	Day	15% 7% 2 6% 5% 5% 5% 4 6% 9% 36%	3040
July	1st to 10th	Day	10% 4 2 5% 4 4 5% 4 7% 9% 47%	5060
	11th to 20th	Day	9% 4 2 5% 3 3 5% 3 6% 9% 52%	4947
	21st to end	Day	7% 4 2 5% 3 4 5% 4 7% 10% 49%	4927
August	1st to 10th	Day	11% 4 2 5% 4 5% 5% 4 7% 10% 43%	4412
	11th to 20th	Day	8% 5% 2 7% 5% 5% 5% 4 5% 8% 47%	4343
	21st to end	Day	13% 5% 2 6% 3 4 4 3 5% 7% 47%	4428
September	1st to 10th	Day	11% 5% 3 6% 5% 5% 5% 4 5% 7% 43%	2280
	11th to 20th	Day	14% 7% 3 6% 4 5% 5% 4 5% 8% 40%	2269
	21st to end	Day	11% 6% 2 7% 4 4 4 3 5% 7% 48%	2057
October	1st to 10th	Day	13% 9% 2 5% 4 3 4 3 5% 7% 44%	3170
	11th to 20th	Day	7% 7% 3 8% 5% 4 6% 4 7% 11% 37%	2943
	21st to end	Day	8% 14% 4 9% 5% 6% 6% 4 6% 6% 31%	3091
November	1st to 10th	Day	16% 17% 5% 10% 5% 5% 4 3 5% 6% 24%	1574
	11th to 20th	Day	9% 16% 6% 14% 9% 7% 4 4 4 5% 22%	1475
	21st to end	Day	8% 16% 6% 13% 8% 5% 5% 4 5% 6% 24%	1400
December	1st to 10th	Day	9% 14% 6% 14% 9% 8% 5% 4 5% 5% 22%	2130
	11th to 20th	Day	6% 12% 6% 16% 9% 7% 6% 4 5% 7% 24%	2259
	21st to end	Day	3 10% 6% 14% 8% 5% 6% 4 5% 5% 35%	2992
January	1st to 10th	Night	4 11% 6% 19% 10% 8% 6% 4 5% 7% 18%	7203
	11th to 20th	Night	4 10% 4 13% 10% 9% 8% 7% 8% 7% 20%	6739
	21st to end	Night	5% 12% 6% 14% 8% 6% 6% 5% 6% 7% 26%	7045
February	1st to 10th	Night	8% 11% 5% 9% 8% 7% 7% 5% 6% 8% 26%	2800
	11th to 20th	Night	4 10% 4 11% 7% 7% 7% 5% 7% 7% 32%	2577
	21st to end	Night	4 9% 4 9% 8% 6% 6% 5% 7% 8% 33%	2054
March	1st to 10th	Night	7% 11% 5% 10% 7% 6% 6% 5% 8% 8% 26%	3854
	11th to 20th	Night	8% 10% 3 10% 6% 6% 6% 5% 7% 9% 32%	3778
	21st to end	Night	5% 7% 3 7% 5% 5% 5% 4 6% 8% 44%	3580
April	1st to 10th	Night	6% 10% 3 7% 5% 4 5% 4 7% 8% 41%	1900
	11th to 20th	Night	13% 10% 3 7% 6% 5% 4 4 7% 7% 35%	1781
	21st to end	Night	15% 8% 3 7% 6% 4 5% 4 6% 8% 34%	1520
May	1st to 10th	Night	17% 10% 3 7% 5% 5% 5% 4 5% 6% 33%	2540
	11th to 20th	Night	11% 8% 3 8% 4 5% 5% 5% 6% 7% 37%	2438
	21st to end	Night	17% 11% 3 8% 5% 4 5% 3 5% 6% 34%	2232
June	1st to 10th	Night	13% 7% 2 4 4 4 4 3 7% 10% 42%	1140
	11th to 20th	Night	17% 8% 3 7% 5% 5% 3 4 6% 7% 34%	1140
	21st to end	Night	13% 6% 1 5% 4 4 5% 3 7% 9% 42%	1140
July	1st to 10th	Night	7% 4 2 6% 4 4 7% 6% 8% 9% 43%	1900
	11th to 20th	Night	8% 4 2 4 3 3 5% 4 6% 7% 54%	2010
	21st to end	Night	5% 3 1 4 3 3 3 3 5% 9% 60%	2630
August	1st to 10th	Night	8% 4 2 5% 3 4 4 4 6% 9% 52%	2528
	11th to 20th	Night	9% 4 1 5% 4 3 4 4 7% 10% 49%	2496
	21st to end	Night	10% 4 1 4 3 3 4 3 6% 8% 52%	3236
September	1st to 10th	Night	10% 6% 2 5% 4 4 4 4 6% 8% 49%	1900
	11th to 20th	Night	15% 6% 2 5% 4 3 4 4 5% 7% 45%	1911
	21st to end	Night	9% 6% 2 5% 4 3 4 4 6% 8% 48%	2121
October	1st to 10th	Night	10% 8% 2 5% 4 4 4 3 5% 8% 47%	3800
	11th to 20th	Night	7% 7% 2 7% 5% 5% 5% 5% 6% 7% 44%	3953
	21st to end	Night	11% 11% 4 9% 4 4 4 4 5% 8% 35%	4467
November	1st to 10th	Night	15% 17% 4 11% 6% 4 5% 3 5% 6% 24%	2720
	11th to 20th	Night	8% 15% 7% 15% 7% 5% 4 3 6% 6% 24%	2925
	21st to end	Night	7% 15% 5% 13% 7% 6% 6% 4 6% 7% 25%	3000
December	1st to 10th	Night	7% 16% 7% 16% 10% 8% 6% 4 4 5% 18%	5051
	11th to 20th	Night	5% 11% 6% 13% 7% 7% 6% 5% 6% 8% 25%	5933
	21st to end	Night	3 9% 5% 15% 7% 5% 4 3 5% 5% 39%	7964

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	62% 4 10% 16% 7%	2741
	11th to 20th	Day	54% 5% 15% 21% 5%	3180
	21st to end	Day	59% 4 18% 16% 3	3930
February	1st to 10th	Day	55% 5% 15% 16% 9%	1600
	11th to 20th	Day	50% 4 12% 23% 10%	1737
	21st to end	Day	58% 3 12% 19% 8%	1576
March	1st to 10th	Day	58% 3 14% 18% 7%	3230
	11th to 20th	Day	49% 5% 17% 22% 7%	3402
	21st to end	Day	40% 4 10% 26% 18% 2	4200
April	1st to 10th	Day	42% 5% 15% 25% 13%	2280
	11th to 20th	Day	53% 5% 12% 20% 9% 2	2348
	21st to end	Day	48% 5% 16% 24% 7% 1	2660
May	1st to 10th	Day	48% 5% 13% 25% 8%	4430
	11th to 20th	Day	45% 6% 11% 25% 12% 1	4469
	21st to end	Day	50% 5% 14% 22% 8%	5347
June	1st to 10th	Day	49% 6% 13% 21% 9% 1	3040
	11th to 20th	Day	56% 6% 12% 18% 8% 1	3040
	21st to end	Day	44% 7% 18% 24% 7%	3040
July	1st to 10th	Day	32% 6% 28% 30% 4	4981
	11th to 20th	Day	29% 5% 20% 42% 4	4860
	21st to end	Day	29% 5% 26% 34% 5%	4771
August	1st to 10th	Day	35% 6% 27% 28% 4	4396
	11th to 20th	Day	36% 5% 23% 29% 7%	4385
	21st to end	Day	37% 4 23% 31% 5%	4427
September	1st to 10th	Day	39% 6% 18% 25% 11% 2	2280
	11th to 20th	Day	42% 6% 19% 26% 7%	2269
	21st to end	Day	37% 5% 16% 29% 12% 1	2057
October	1st to 10th	Day	40% 3 20% 28% 8%	3170
	11th to 20th	Day	40% 4 22% 27% 6% 1	2943
	21st to end	Day	52% 4 20% 21% 2	3091
November	1st to 10th	Day	62% 4 12% 17% 5%	1574
	11th to 20th	Day	65% 5% 15% 13% 3	1475
	21st to end	Day	61% 5% 15% 16% 4	1400
December	1st to 10th	Day	64% 6% 10% 16% 4 1	2130
	11th to 20th	Day	61% 3 15% 17% 4	2260
	21st to end	Day	50% 4 10% 20% 12% 3	2992
January	1st to 10th	Night	65% 4 10% 18% 4	7203
	11th to 20th	Night	59% 5% 13% 17% 5%	6780
	21st to end	Night	57% 7% 18% 15% 3	7045
February	1st to 10th	Night	54% 5% 13% 19% 9%	2800
	11th to 20th	Night	50% 4 12% 23% 10%	2578
	21st to end	Night	47% 5% 14% 23% 11%	2054
March	1st to 10th	Night	52% 5% 17% 22% 3 1	3854
	11th to 20th	Night	46% 7% 15% 22% 10%	3778
	21st to end	Night	37% 5% 9% 25% 22% 3	3580
April	1st to 10th	Night	39% 4 12% 27% 15% 2	1900
	11th to 20th	Night	47% 5% 12% 19% 15% 3	1781
	21st to end	Night	47% 4 14% 24% 10% 1	1520
May	1st to 10th	Night	50% 4 11% 23% 11% 1	2540
	11th to 20th	Night	43% 6% 11% 24% 15% 2	2438
	21st to end	Night	51% 6% 10% 25% 8%	2232
June	1st to 10th	Night	36% 6% 19% 26% 12% 1	1140
	11th to 20th	Night	47% 7% 16% 17% 12% 1	1140
	21st to end	Night	37% 6% 21% 24% 10% 1	1140
July	1st to 10th	Night	34% 7% 25% 29% 6%	1870
	11th to 20th	Night	28% 5% 15% 44% 8%	1974
	21st to end	Night	22% 4 25% 40% 8%	2547
August	1st to 10th	Night	29% 5% 24% 33% 8%	2520
	11th to 20th	Night	30% 5% 19% 38% 7%	2520
	21st to end	Night	30% 5% 22% 34% 9%	3236
September	1st to 10th	Night	34% 4 18% 30% 13% 2	1900
	11th to 20th	Night	38% 4 18% 31% 9%	1911
	21st to end	Night	33% 4 17% 29% 16% 1	2121
October	1st to 10th	Night	36% 3 19% 32% 9%	3800
	11th to 20th	Night	39% 4 15% 32% 10%	3953
	21st to end	Night	48% 4 19% 24% 5%	4467
November	1st to 10th	Night	61% 4 13% 16% 5% 1	2720
	11th to 20th	Night	61% 4 16% 15% 4	2925
	21st to end	Night	58% 6% 16% 17% 3	3000
December	1st to 10th	Night	70% 5% 8% 13% 4	5051
	11th to 20th	Night	56% 4 15% 20% 5%	5931
	21st to end	Night	49% 3 10% 23% 13% 2	7964

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	13% 5% 35% 22% 21% 5%	200
	11th to 20th	Day	13% 5% 33% 33% 15% 3	200
	21st to end	Day	17% 7% 26% 33% 16% 1	313
February	1st to 10th	Day	10% 9% 32% 33% 14% 2	300
	11th to 20th	Day	10% 4 27% 34% 20% 6%	300
	21st to end	Day	7% 6% 31% 33% 17% 5%	249
March	1st to 10th	Day	13% 4 30% 33% 17% 2	300
	11th to 20th	Day	11% 8% 30% 32% 16% 4	380
	21st to end	Day	14% 5% 29% 32% 16% 4	531
April	1st to 10th	Day	11% 10% 33% 28% 13% 6%	460
	11th to 20th	Day	19% 9% 26% 29% 13% 3	524
	21st to end	Day	14% 8% 29% 31% 16% 3	650
May	1st to 10th	Day	15% 6% 25% 31% 17% 5%	653
	11th to 20th	Day	12% 8% 27% 28% 19% 7%	675
	21st to end	Day	21% 5% 23% 24% 23% 4	734
June	1st to 10th	Day	18% 7% 28% 27% 16% 4	680
	11th to 20th	Day	24% 9% 25% 23% 15% 4	680
	21st to end	Day	19% 5% 21% 28% 20% 7%	680
July	1st to 10th	Day	11% 5% 20% 32% 23% 8%	671
	11th to 20th	Day	14% 7% 19% 32% 21% 7%	668
	21st to end	Day	11% 5% 23% 30% 23% 9%	739
August	1st to 10th	Day	12% 5% 20% 29% 26% 8%	676
	11th to 20th	Day	10% 4 22% 32% 23% 9%	665
	21st to end	Day	15% 7% 24% 34% 15% 5%	610
September	1st to 10th	Day	15% 11% 29% 27% 16% 2	490
	11th to 20th	Day	18% 5% 30% 31% 14% 3	479
	21st to end	Day	13% 11% 28% 31% 15% 2	300
October	1st to 10th	Day	21% 7% 26% 27% 17% 3	300
	11th to 20th	Day	12% 11% 34% 28% 11% 4	300
	21st to end	Day	19% 9% 31% 27% 13% 2	330
November	1st to 10th	Day	23% 5% 31% 28% 10% 3	300
	11th to 20th	Day	18% 7% 37% 31% 6% 1	300
	21st to end	Day	15% 8% 38% 26% 10% 3	300
December	1st to 10th	Day	8% 9% 34% 32% 13% 3	253
	11th to 20th	Day	14% 8% 34% 38% 8% 1	200
	21st to end	Day	5% 4 30% 34% 20% 7%	220
January	1st to 10th	Night	12% 6% 32% 35% 13% 2	1000
	11th to 20th	Night	13% 6% 36% 33% 10% 1	1000
	21st to end	Night	15% 7% 36% 32% 10% 1	1100
February	1st to 10th	Night	13% 4 30% 37% 14% 2	1000
	11th to 20th	Night	8% 5% 30% 36% 17% 3	829
	21st to end	Night	8% 5% 27% 38% 19% 3	660
March	1st to 10th	Night	15% 5% 27% 36% 15% 3	800
	11th to 20th	Night	13% 5% 32% 36% 12% 2	800
	21st to end	Night	11% 4 29% 35% 18% 3	672
April	1st to 10th	Night	10% 5% 30% 37% 15% 3	570
	11th to 20th	Night	18% 6% 28% 33% 13% 2	563
	21st to end	Night	18% 6% 28% 37% 10% 1	570
May	1st to 10th	Night	16% 4 30% 35% 15% 1	570
	11th to 20th	Night	13% 5% 28% 35% 17% 2	561
	21st to end	Night	19% 4 23% 37% 16% 1	513
June	1st to 10th	Night	17% 7% 28% 31% 16% 2	380
	11th to 20th	Night	22% 6% 21% 34% 15% 2	380
	21st to end	Night	16% 5% 18% 41% 20% 1	380
July	1st to 10th	Night	9% 3 20% 43% 25% 1	370
	11th to 20th	Night	15% 3 19% 38% 23% 2	368
	21st to end	Night	9% 4 22% 37% 23% 4	544
August	1st to 10th	Night	9% 4 22% 36% 26% 4	567
	11th to 20th	Night	11% 2 20% 38% 26% 3	564
	21st to end	Night	15% 4 24% 37% 18% 2	627
September	1st to 10th	Night	14% 3 25% 37% 19% 3	570
	11th to 20th	Night	18% 4 24% 38% 15% 1	570
	21st to end	Night	11% 5% 34% 38% 10% 1	601
October	1st to 10th	Night	19% 4 28% 35% 12% 1	760
	11th to 20th	Night	14% 6% 30% 35% 13% 2	858
	21st to end	Night	19% 7% 31% 31% 11% 1	1045
November	1st to 10th	Night	25% 5% 30% 30% 9% 2	975
	11th to 20th	Night	14% 8% 35% 29% 12% 2	1000
	21st to end	Night	14% 8% 36% 31% 9% 1	1000
December	1st to 10th	Night	11% 6% 32% 32% 15% 3	1000
	11th to 20th	Night	13% 8% 33% 33% 12% 2	1000
	21st to end	Night	11% 4 27% 35% 19% 4	1100

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